10 TH SCHOOL OF FUSION PHYSICS & TECHNOLOGY ABSTRACTS ΠΕΡΙΛΗΨΕΙΣ 10 Ο ΣΧΟΛΕΙΟ ΦΥΣΙΚΗΣ & ΤΕΧΝΟΛΟΓΙΑΣ ΣΥΝΤΗΞΗΣ. Volos 9 13 May 2011

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1 ΕΝΩΣΗ EURATOM ΕΛΛΗΝΙΚΗ ΔΗΜΟΚΡΑΤΙΑ ASSOCIATION EURATOM HELLENIC REPUBLIC 10 TH SCHOOL OF FUSION PHYSICS & TECHNOLOGY ABSTRACTS ΠΕΡΙΛΗΨΕΙΣ 10 Ο ΣΧΟΛΕΙΟ ΦΥΣΙΚΗΣ & ΤΕΧΝΟΛΟΓΙΑΣ ΣΥΝΤΗΞΗΣ Volos 9 13 May 2011 UNIVERSITY OF THESSALY DEPARTMENT OF MECHANICAL ENGINEERING Auditoria: Mechanical & Planning Engineering Athens Avenue & Sekeri Str Volos Greece (Info: Tel /75 or Tel/Fax ) Website: We look forward to your active participation in the 10 th School of Fusion Physics & Technology The Scientific Programme Committee & the Organizing Committee 1

2 FOREWORD The 10 th School of Fusion Physics & Technology brings together students who have heard little about plasma and fusion, doctoral candidates who are working on problems related to fusion, researchers working on fusion topics for some years and academics staff from universities who are coordinating MHD and fusion research. Also, distinguished researchers from Europe and the USA will give invited talks. The joint attendance of such a school by all these scientists and engineers creates additional needs and is going beyond traditional schools. Thus, the programme committee developed a multi level series of lectures with the aim to satisfy as many of the audience needs as possible. The programme is divided in three categories: School Classes, Invited Lectures, and Workshops or Advanced Seminars. The School will start Monday morning with the lectures on topics of common interest to all, such as fusion for energy, electrodynamics and plasma physics. The current status of fusion research in Europe will be presented in early afternoon followed by introductory School classes on charged particle dynamics. The afternoon will end with a interesting lecture on energy, environment and fusion. The School will continue on Tuesday morning with lectures on kinetic theory, followed by asymptotic methods and vacuum technology in early afternoon while the first «Workshop on Stochastic Modeling & Transport» will be held in the afternoon with advanced seminars presented by invited speakers and expert researchers. The afternoon will end with α lecture on fusion energy and the first «Teacher Student Interaction» with general and specific questions posed by students to be answered by their teachers. Wednesday morning will be devoted to School classes on dynamics of electrically conducting fluids, MHD theory, CFD, plasma transport, and MHD and plasma instability. In the afternoon, the second «Workshop on MHD & Plasma Stability» will be held. The day will close with the «School Dinner», where all participants are welcome. The School will continue on Thursday morning with lectures on plasma heating and gyrotron technologies followed in the afternoon by the third «Workshop on Gyrotrons & Electron Cyclotron Resonance Heating». The afternoon will end with the second and final «Teacher Student Interaction». Friday morning will be the last session of School classes on materials at high temperatures for fusion, followed by a «Mini Symposium on Vacuum Flows, Viscous MHD, Turbulence & Heat Transfer». The 10th School of Fusion Science & Technology will end on Friday afternoon with closing remarks and comments by the organizers and attendees, followed by the delivery of «Certificates of Attendance» to all «good standing» participants. In this manner the School of Fusion Physics & Technology serves as a multidisciplinary forum covering many interesting fields. We do hope that you will find the programme structure rewarding, and we look forward to your active participation, which will warranty its success. In concluding, the organizers of the Fusion Schools in Volos would like to express their sincere thanks to the European Commission, the Hellenic General Secretariat of Research & Technology, and the University of Thessaly for their continuous support, which make possible these productive meetings on Fusion science and technology. Volos Monday, 9 May 2011 The Scientific Programme and Organizing Committees 2/20

3 ΠΡΟΛΟΓΟΣ Το 10 ο Σχολείο Φυσικής & Τεχνολογίας Σύντηξης φέρνει μαζί φοιτητές που έχουν ακούσει ελάχιστα για πλάσμα και σύντηξη, υποψήφιους διδάκτορες που εργάζονται σε προβλήματα σχετικά με σύντηξη, ερευνητές που ασχολούνται με θέματα σύντηξης αρκετά χρόνια, και μέλη ΔΕΠ πανεπιστημίων που κατευθύνουν έρευνα σε ΜΥΔ και σύντηξη. Επίσης, διακεκριμένοι ερευνητές από την Ευρώπη και ΗΠΑ θα κάνουν προσκεκλημένες ομιλίες. Η κοινή παρακολούθηση ενός τέτοιου σχολείου από όλους τους παραπάνω είναι φυσικό να δημιουργεί πρόσθετες ανάγκες και να ξεφεύγει από τα παραδοσιακά σχολεία. Έτσι, η επιτροπή προγράμματος ανέπτυξε μία πολυ επίπεδη σειρά διαλέξεων με στόχο να ικανοποιήσει όσο το δυνατόν περισσότερες από τις ανάγκες του ακροατηρίου. Το πρόγραμμα χωρίζεται σε τρεις ενότητες: Μαθήματα Σχολείου, Προσκεκλημένες Ομιλίες και Σεμινάρια Εμβάθυνσης. Το Σχολείο ξεκινά την Δευτέρα το πρωί με τις ομιλίες σε θέματα κοινού ενδιαφέροντος για όλους, όπως ενέργεια από σύντηξη, ηλεκτροδυναμική και φυσική πλάσματος. Η σημεριν κατάσταση της έρευνας για την σύντηξη στην Ευρώπη θα παρουσιασθεί νωρίς το απόγευμα και θα ακολουθήσουν μαθήματα Σχολείου πάνω σε δυναμική φορτισμένων σωματιδίων. Το απόγευμα θα κλείσει με μια ενδιαφέρουσα διάλεξη σε ενέργεια, περιβάλλον και σύντηξη. Το Σχολείο θα συνεχιστεί την Τρίτη το πρωί με μαθήματα σε κινητική θεωρία, και νωρίς το απόγευμα με διαλέξεις σε ασυμπτωτικές μεθόδους και τεχνολογίες κενού, ενώ το απόγευμα θα διεξαχθεί η πρώτη σειρά «Σεμιναρίων Εμβάθυνσης σε Στοχαστικά Μοντέλα & Μεταφορά» με παρουσιάσεις από προσκεκλημένους ομιλητές και έμπειρους ερευνητές. Το απόγευμα θα κλείσει με διάλεξη για ενέργεια από σύντηξη και την πρώτη «Αλληλεπίδραση Διδασκόντων Φοιτητών» με γενικές και ειδικές ερωτήσεις από φοιτητές που θα απαντηθούν από τους καθηγητές τους. Το πρωί της Τετάρτης θα αφιερωθεί σε μαθήματα Σχολείου πάνω στην δυναμική ηλεκτρικά αγωγίμων ρευστών, ΜΥΔ θεωρία, CFD, μεταφορά σε πλάσμα, και ΜΥΔ και αστάθεια πλάσματος. Το απόγευμα, θα διεξαχθεί η δεύτερη σειρά «Σεμιναρίων Εμβάθυνσης σε ΜΥΔ & Αστάθεια Πλάσματος». Η ημέρα θα κλείσει με το «Δείπνο του Σχολείου», όπου όλοι οι συμμετέχοντες είναι ευπρόσδεκτοι. Το Σχολείο θα συνεχιστεί την Πέμπτη το πρωί με διαλέξεις πάνω σε θέρμανση πλάσματος και τεχνολογίες γυροτρονίων, ακολουθούμενες το απόγευμα με την τρίτη σειρά «Σεμιναρίων Εμβάθυνσης σε Γυροτρόνια & Θέρμανση με Κυκλοτρόνια Ηλεκρονιων». Το απόγευμα θα κλείσει με την δεύτερη και τελευταία «Αλληλεπίδραση Διδασκόντων Φοιτητών». Την Παρασκευή το πρωί θα γίνουν τα τελευταία μαθήματα του Σχολείου πάνω σε υλικά υψηλών θερμοκρασιών για σύντηξη, ακολουθούμενα από ένα «Μίνι Συμπόσιο σε Ροές Κενού, Μαγνητο υδροδυναμική, Τύρβη & Μεταφορά Θερμότητας». Το 10 ο Σχολείο Φυσικής & Τεχνολογίας Σύντηξης θα κλείσει την Παρασκευή το απόγευμα με συνοπτικά συμπεράσματα από τους οργανωτές και παρεμβάσεις από τους συμμετέχοντες, και θα διανεμηθούν τα Πιστοποιητικά Παρακολούθησης σε όσους το παρακολούθησαν «καλώς». Με τον τρόπο αυτό το Σχολείο Φυσικής & Τεχνολογίας Σύντηξης λειτουργεί ως ένας πολύ επιστημονικός χώρος που καλύπτει πολλά ενδιαφέροντα. Ελπίζουμε ότι θα βρείτε αυτή την δομή του προγράμματος χρήσιμη και προσδοκούμε στην ενεργή συμμετοχή σας που θα εξασφαλίσει την επιτυχία του. Κλείνοντας, οι οργανωτές των Σχολείων Σύντηξης Βόλου επιθυμούν να εκφράσουν τις θερμές ευχαριστίες τους στην Ευρωπαϊκή Επιτροπή, την Γενική Γραμματεία Έρευνας & Τεχνολογίας, και το Πανεπιστήμιο Θεσσαλίας για την συνεχή υποστήριξη, που καθιστά δυνατή αυτή την παραγωγική συνάντηση για την φυσική και τεχνολογία Σύντηξης. Βόλος Δευτέρα, 9 Μαΐου 2011 Η Επιτροπή Προγράμματος και η Οργανωτική Επιτροπή 3/20

4 CONTENTS SCHOOL LECTURES (PLENARY SESSIONS: ) Page S.01 J. Vomvoridis: Basics of Fusion for Energy 06 S.02 A. Anastasiadis: Basic concepts of plasmas 06 S.03 R. Giannella: Activities of the European Fusion Associations 06 S.04 Y. Kominis: Charged particle dynamics 06 S.05 A. Ram: Energy, environment and thermonuclear fusion 06 S.06 J. Vomvoridis: Kinetic theory 07 S.07 D. Valougeorgis: Kinetic modelling for vacuum flows in DT fusion reactors 07 S.08 L. Buehler: Asymptotic methods for modeling of liquid metal flows in strong magnetic fields 07 S.09 C. Day: Size matters The vacuum systems of ITER and beyond 07 WORKSHOP 1: KINETIC THEORY AND TRANSPORT W1.1 I. Kominis, A. Ram, K. Hizanidis: Kinetic formulation of transport of charged particles interacting with coherent EM waves in plasmas 08 W1.2 H. Isliker: Particle and heat transport in turbulent environment: A unified approach to deterministic, stochastic, and fractional transport 08 SCHOOL LECTURES (PLENARY SESSIONS: 5 8) S.10 A. Ram: Fusion energy: Dancing with the stars 08 S.11 D. Carati: Dynamics of electrically conducting fluids 09 S.12 G. Throumoulopoulos: Introduction to Magnetohydrodynamics 09 S.13 P. Lalousis: Compressible MHD (ideal/resistive) 09 S.14 V. Igochine: Introduction to plasma stability 09 S.15 V. Igochine: Operational limits and MHD instabilities in modern tokamaks and ITER 09 S.16 N. Pelekasis: Introduction to hydrodynamic and MHD stability 10 WORKSHOP 2: MHD FLOWS AND PLASMA STABILITY W2.1 L. Buehler, C. Mistrangelo: Analysis of liquid metal MHD flows in the European Test Blanket module 10 W2.2 L. Vlahos: Instabilities driven by energetic particles 10 W2.3 G. Poulipoulis, G. Throumoulopoulos, C. Konz: Extending HELENA to equilibria with flow 10 SCHOOL LECTURES (PLENARY SESSIONS: 9 10) S.17 A. Ram: Heating and current drive by radio frequency waves 11 S.18 C. Tsironis: Modeling of electromagnetic wave propagation in tokamak devices and applications 11 S.19 J. P. Hogge: A gyrotron overview 11 S.20 E. Borie: Simulation of RF behavior in the gyrotron cavity 11 WORKSHOP 3: GYROTRONS ELECTRON CYCLOTRON RESONANCE HEATING W3.1 J. P. Hogge: Gyrotrons for the ITER ECRH System 12 W3.2 E. Borie: Development of 140 GHz, 1MW CW gyrotrons for fusion applications Progress and recent results 12 W3.3 K. Avramides: Gyrotron interaction simulations with tapered magnetοstatic field 12 W3.4 G. Anastassiou: Power enhancement of the Gaussian RF beam of a gyrotron 12 W3.5 I. Tigelis: Recent numerical results for gyrotron beam tunnels by CST 12 W3.6 M. Moraitou: Numerical results for TE and hybrid modes in corrugated coaxial wave guides 12 W3.7 S. Moustaizis: Progress on compact magnetic fusion devices: initiative for a Neutron Test Facility 12 4/20

5 SCHOOL LECTURES (PLENARY SESSIONS: 9 10) S.21 S. Moustaizis: Negative ions Neutral beams & potential applications to magnetic fusion 13 S.22 G. Haidemenopoulos, A. Kermanidis: Materials at high temperatures 13 S.23 P. Grammatikopoulos: Fusion relevant materials: Problems and prospectives 13 MINI SYPOSIUM: MODELING VACUUM FLOWS, VISCOUS MHD, TURBULENCE AND HEAT TRANSFER MS00 P. Grammatikopoulos: Computer simulation of dislocation interaction with radiation induced obstacles in iron 14 MS01 D. Carati: Particle tracking in MHD turbulence 14 MS02 C. Dritselis, N. Vlachos: MHD turbulent channel flow with heat transfer 15 MS03 S. Pantazis, S. Misdanitis, D. Valougeorgis: Simulation of non linear flows under any vacuum conditions 15 MS04 J. Lihnaropoulos, D. Valougeorgis: Transient vacuum gas flows through cylindrical ducts 15 MS05 P. Lalousis: Fuelling of fusion reactors 15 MS06 A. Sergis: Anomalous heat transfer modes of nanofluids: A review based on statistical analysis 15 MS07 S. Misdanitis, D. Valougeorgis: Design of gas distribution systems consisting of long tubes under any vacuum conditions 16 MS08 D. Dimopoulos, N. Pelekasis: Magnetic field effects on 3D stability of natural convection in differentially heated cavities 16 MS09 S. Kakarantzas, B. Knaepen: Simulation and modelling of the IFMIF Lithium target flow 16 MS10 A. Iatridis, I. Sarris, N. Vlachos: Direct numerical simulation of magnetohydrodynamic flow in toroidal ducts 17 MS11 I. Sarris, D. Carati: Large eddy simulation of non equilibrium Kolmogorov flow in the presence of external magnetic fields 17 POSTERS OF RESEARCH ACTIVITIES RP01 Ι. Arapoglou, G.N. Throumoulopoulos, H. Tasso: Paramagnetic Solovev equilibrium 17 RP02 E.Benos, I.E. Sarris, N. Vlachos: Numerical modeling of plasma flows using the CFD library OpenFoam 17 RP03 C.Dritselis, I.Sarris, D.Fidaros, N.Vlachos: Transport and deposition of neutral particles in MHD turbulent channel flows at low Rm 18 RP04 H. Isliker, D. Constantinescu, L. Vlahos: Fractional transport equations and their numerical solution 18 RP05 S. Kakarantzas, I. Sarris, N. Vlachos: Natural convection of a liquid metal in a vertical annulus with lateral and volumetric heating in the presence of an horizontalmagnetic field 18 RP06 S. Pantazis, S. Varoutis, V. Hauer, C. Day. D. Valougeorgis: Gas surface scattering effect on vacuum gas flows through rectangular channels 18 RP07 K. Perrakis, S. Moustaizis: Production of negative ion beam (H D) and development of neutral beam using laser technology for applications in tokamaks 18 RP08 Th. Pisokas, H. Isliker, L. Vlahos: CHET1: a CHEbyshev pseudospectral code solving Transport problems 19 RP09 I. Sarris, D. Grigoriadis, N. Vlachos: Laminar free convection in a square enclosure driven by the Lorentz force 19 RP10 I. Sarris, A. Iatrides, C. Dritselis, N. Vlachos: Magnetic field effect on the cooling of low Pr fluids in a vertical cylinder 19 RP11 H. Tasso, G. Throumoulopoulos: A comparison of Vlasov with drift kinetic and gyrokinetic theories 19 RP12 A. Xagoni, K. Hizanidis: Neutron stars magneto hydro dynamics 19 AUTHORS / SPEAKERS 20 POSTER PRESENTERS 20 PROCEEDINGS: ALL PARTICIPANTS are kindly requested to submit their presentations in PDF for the School Web The editor wishes to thank all authors for their contribution to the Book of Abstracts. The support of the European Commission, the Greek General Secretariat for R&T, and the University of Thessaly is gratefully acknowledged (NSV May 2011) 5/20

6 SCHOOL LECTURES (PLENARY SESSIONS: ) S.01 John Vomvoridis: Basics of Fusion for Energy National Technical University of Athens, Greece The basic ideas behind the international efforts to produce energy from the fusion of light nuclei (e.g. isotopes of hydrogen) will be discussed. The basic equations of fusion reactions will also be presented and discussed. The relavant technologies of fusion devices will be briefly reviewd and the major unresolved scientific and technological issues will be presented. Finally, in the framework of the European Fusion Programme, the national programme for controlled thermonuclear fusion will be outlined with reference to the groups involved in fusion research in Greece and Cyprus. S.02 Anastasios Anastasiadis: Basic Concepts of Plasmas Institute for Space Applications & Remote Sensing, National Observatory of Athens, Greece Τι είναι το Πλάσμα: Πλάσμα στην φύση και στο εργαστήριο, Παράμετροι πλάσματος (πυκνότητες, θερμοκρασίες), Η εξίσωση Saha, Μέθοδοι περιγραφής του πλάσματος (μικρο μακροσκοπική περιγραφή), Κίνηση σωματιδίων, Εξισώσεις Maxwell. Βασικές παράμετροι πλάσματος: Μήκος και σφαίρα Debye, Ηλεκτροστατικό δυναμικόθωράκιση, Οιονεί ουδετερότητα, Συχνότητα πλάσματος, Μαγνητισμένο πλάσμα. Συγκρούσεις Coulomb: Συχνότητα συγκρούσεων, Συγκρούσεις με ουδέτερα σωματίδια, Ηλεκτρική αντίσταση πλάσματος. S.03 Ruggerro Giannella: Activities of the European Fusion Associations Directorate General for Research, European Commission, Brussels, Belgium Fusion research in Europe is aimed at demonstrating that nuclear fusion is a viable future energy option. Achieving this aim requires a sustained, long term and large scale research effort, impossible to be sustained by any single European country. Fusion research organisations in the Member states have so called "Contracts of Association" with the European Commission (representing Euratom), in which the long term commitments and work plans are laid down. In 1999, the European Fusion Development Agreement (EFDA) was created to provide a framework between European fusion research institutions and the European Commission to strengthen their coordination and collaboration, and to participate in collective activities. From 1999 to 2007 EFDA was responsible for the exploitation of the Joint European Torus, the coordination and support of fusionrelated research and development activities carried out by the Associations and by European Industry, and coordination of the European contribution to large scale international collaborations, such as the ITER project. With the appearance of Fusion for Energy (F4E), the european domestic agency for ITER, EFDA s role has changed and it has been reorganised. A revised European Fusion Development Agreement entered into force on 1 January 2008 focusing on research coordination with two main objectives: to prepare for the operation and exploitation of ITER and to further develop and consolidate the knowledge base needed for overall fusion development and in particular for DEMO, the first electricity producing experimental fusion power plant. S.04 Yannis Kominis: Charged particle dynamics National Technical University of Athens, Greece Τροχιές φορτισμένων σωματιδίων σε στατικά πεδία: Κίνηση σε στατικό ομογενές ηλεκτρικό πεδίο, Κίνηση σε στατικό ομογενές μαγνητικό πεδίο, Ολίσθηση E B, Κίνηση σε μη ομογενές στατικό ηλεκτρικό πεδίο, Κίνηση σε μη ομογενές στατικό μαγνητικό πεδίο (διαμήκης ανομοιογένεια, εγκάρσια ανομοιογένεια, καμπυλότητα πεδιακών γραμμών), Αδιαβατικές σταθερές. Αλληλεπίδραση φορτισμένων σωματιδίων με κύματα: Ομαλή και χαοτική κίνηση φορτισμένου σωματιδίου σε ομογενές στατικό μαγνητικό πεδίο υπό την επίδραση ηλεκτροστατικών κυμάτων (Χαμιλτονιανή περιγραφή της κίνησης φορτισμένου σωματιδίου, Κανονική θεωρία διαταραχών και υπολογισμός προσεγγιστικών σταθερών της κίνησης, Ο ρόλος των συντονισμών και το πρόβλημα των μικρών παρονομαστών, Επικάλυψη των συντονισμών και μετάβαση στο χάος), Περιπτώσεις (Διάδοση κύματος υπό διαφορετικές γωνίες ως προς το μαγνητικό πεδίο, Κυμάτων διακριτού και συνεχούς φάσματος). S.05 Abhay Ram: Energy, environment and thermonuclear fusion Massachusetts Inst. of Technology, USA The global demands for energy are increasing at a rapid pace. The resources being used to satisfy the energy needs are leading to concerns about the environment and the climate. This talk will compare and contrast per capita energy consumption, means of energy production, and the human development index of a few chosen countries. A large fraction of the energy is produced from fossil fuels, which in turn, impacts the environment. The role that thermonuclear fusion can play in nourishing our energy needs without adversely affecting the environment will be discussed. 6/20

7 S.06 John Vomvoridis: Kinetic theory (Κινητική Θεωρία) National Technical University of Athens, Greece Η συνάρτηση κατανομής: Ροπές της συνάρτησης κατανομής, Βασικές συναρτήσεις. Οι κινητικές εξισώσεις. Εφαρμογές κινητικής θεωρίας (Στατικές καταστάσεις ισορροπίας, Διάδοση κυμάτων (μικρού πλάτους) σε πλάσμα. Κύματα Langmuir σε μη μαγνητισμένο πλάσμα. Απόσβεση Landau. S.07 Dimitris Valougeorgis: Kinetic modeling for vacuum flows in DT fusion reactors Department of Mechanical, University of Thessaly, Volos, Greece All large fusion devices and in particular DT fusion machines, such as ITER and DEMO, require the existence and smooth operation of advanced and demanding vacuum pumping systems, which are needed for the generation, evacuation and maintenance of the specified pressure levels in the torus, the NBI and the cryostat. The flow conditions in the pumping systems cover the whole range of the Knudsen number. The accurate design of such systems (pumps and piping) is still a challenge. The main approach capable of handling such flows is kinetic theory. Here a brief overview of the vacuum systems and conditions of DT fusion machines is presented. Then, based on kinetic theory some specific flow configurations are examined. Suitable kinetic model equations coupled with appropriate boundary conditions are formulated and solved numerically both in a deterministic and probabilistic manner. The deterministic scheme is based on the discretization of the applied kinetic equations in the physical and molecular velocity spaces, while the probabilistic scheme on the direct simulation of a sample of model molecules, which statistically mimics the behavior of real molecules. Results for the flow rates and the pressure drop are presented for flows through basic elements of vacuum systems such as channels of infinite and finite length and various cross sections. Simulation of unsteady flows is also discussed. Comparisons with available experimental work are included. S.08 Leo Buehler: Asymptotic methods for modeling of liquid metal flows in strong magnetic fields Karlsruhe Institute of Technology, FZK, Karlsruhe, Germany A key issue for the design of reliable liquid metal blankets for fusion reactors is the accurate prediction of magnetohydrodynamic flows. The latter ones occur when the electrically conducting liquid breeder or coolant is circulated through the blanket in the region where the plasma confining magnetic field is present. The strong magneto hydrodynamic interaction has a decisive impact on the thermo mechanical layout of liquid metal blankets. Despite the fast development of numerical techniques and increasing computational power, nowadays it is still not possible to simulate complex 3D MHD flows in blanket components at fusion relevant parameters. Asymptotic methods are efficient tools for predicting magnetohydrodynamic flows in intense magnetic fields, i.e. when electromagnetic forces dominate in the problem. They have been applied since several decades for investigations of engineering applications like liquid metal flows in fusion blankets or in crystal growth technology. The basic assumptions used to derive asymptotic solutions are introduced and the strategy for obtaining efficient solution procedures is outlined. The impact of strong magnetic fields and resulting consequences for 3D MHD flows are discussed. S.09 Christian Day: Size matters The vacuum systems of ITER and beyond Karlsruhe Institute of Technology, Inst. for Technical Physics, Karlsruhe, Germany Any large fusion device and ITER is an example of that is a large vacuum facility which comprises many auxiliary and service vacuum sub systems as well as high speed cryogenic vacuum systems for evacuation and maintenance of the required pressure levels. Over the last two decades, KIT has become the leading association in the development of the ITER vacuum systems. A central function provided by the cryogenic pumping systems is the control of the gas throughput which is one of the key issues affecting the performance and achievable burn time of a fusion reactor. The main pumping systems are the torus exhaust pumping system with eight identical cryopumps (each having a molecular flow pumping speed of about 80 m 3 /s) located in five pumping ports, the cryopumps for the neutral beam injection systems for plasma heating (with a pumping speed of about 4800 m 3 /s per injector), and two cryopumps for the ITER cryostat (similar to the torus cryopumps). All customized cryosorption pumps are force cooled with supercritical helium and share a similar modular design of charcoal coated cryosorption pumping panels.the talk will start with an overview of the vacuum systems at ITER. In the second part, an outline of the development path which was needed to come up with a sound design for the ITER cryopumps is given, and the most prominent results are presented. Special emphasis will be placed on the area of vacuum flows, in which significant progress has been achieved in the last years. In the third part, the current status with respect to the ITER time plan is discussed and the next steps are described. Finally, an outlook will be given to a fusion power plant and the associated issues which have to be solved on the way towards that. 7/20

8 WORKSHOP 1: KINETIC THEORY AND TRANSPORT W1.1 Ioannis Kominis, Abhay Ram, Kyriakos Hizanidis: Kinetic formulation of transport of charged particles interacting with coherent EM waves in plasmas National Technical University of Athens & Massachusetts Inst. of Technology, USA We have developed a general kinetic theory for momentum and spatial transport of charged particles by radio frequency (RF) waves in the presence of magnetic field perturbations, e.g. due to neoclassical tearing modes (NTM), in a tokamak plasma [1]. The kinetic formalism is valid is particularly useful for modeling RF induced currents in tokamaks. It applies to present day machines as well as to ITER where electron cyclotron waves will be used for controlling the NTMs. Our theory, in contrast to the usual quasilinear (QL) theories takes into account the long time correlations that persist in the dynamical phase space of the particles interacting with coherent RF waves. In QL theory it is assumed that the RF waves continuously act on particles randomizing their motion with respect to the phase of the wave in a short interaction time. This is akin to the Markovian assumption and is characterized by phase mixing and ergodicity. However, for coherent RF waves, the particle phase space is a mix of chaotic and coherent motion with islands of coherent motion embedded within chaotic regions. Also, the phase space is bounded as particles do not continuously interact with the same spectrum of waves either the waves evolve in time or are spatially confined. In the vicinity of phase space boundaries and islands, the particle motion is correlated over long times much longer than an interaction time. By taking the actual phase space structure into account, our kinetic theory for evolution of the distribution function during wave particle interactions does not possess the singular structure of QL theories. The master equation is time reversible and the operator evolving the distribution function is time dependent and non singular. From this equation we can construct a hierarchy of equations by sequential averaging over various phases (e.g., phases related to the Larmor, bounce and drift motion in a tokamak). The final one, obtained by averaging over all phases, leads to a well behaved time dependent diffusion operator which is amenable to implementation in numerical codes. It also describes wave particle interactions which are outside the scope of QL theories. Results and comparisons with the QL theory will be presented. [1] Y. Kominis, A. K. Ram, and K. Hizanidis Phys. Plasmas 15, (2008). W1.2 Heinz Isliker: Particle and heat transport in turbulent environment: A unified approach to deterministic, stochastic and fractional transport Department of Physics, Aristotle University of Thessaloniki, Greece We present a simple, but general conservation law in state space that is formulated in terms of probabilities, and that actually expresses a mathematical identity in probability theory. The conservation law is an integral equation, it hence allows for non local effects in space, velocity and time, and it can naturally be interpreted as describing a general random walk process. It is then shown how from the conservation law the classical diffusion equation, as well as the standard Fokker Planck equation, can be derived, basically by excluding nonlocal effects. These equations are models of classical, stochastic transport. In a second step, it will be shown how from the state space conservation law also deterministic transport equations can be derived, namely the Boltzmann equation and, more specific for the case of plasma, the Vlasov equation. In a third step, nonlocalities will explicitly be allowed by making use of Levy distributions in the state space conservation law, which, in the random walk picture, corresponds to Levy walks in state space. The fluid limit will then be applied to the conservation law, which leads to the fractional Fokker Planck equation. It will be discussed how the deterministic, stochastic, and fractional transport equations, due to their common derivation from the same conservation law, can be combined into a realistic transport model for plasma turbulence that includes static background magnetic fields, turbulent magnetic and electric fields, and collisions. SCHOOL LECTURES (PLENARY SESSIONS: 5 8) S.10 Abhay Ram: Fusion energy: Dancing with the stars Massachusetts Institute of Technology, USA How do our earthly efforts to generate fusion energy compare with nature's working fusion reactors? This highly illustrative talk will compare and contrast the approach to fusion from a laboratory perspective with that taken by nature in forming and operating the Sun. The progress towards energy's holy grail will be part of the presentation. 8/20

9 S.11 Daniele Carati: Dynamics of electrically conducting fluids Physique Statistique et Plasmas, Université Libre de Bruxelles, Brussels, Belgium Electrically conducting fluids are described by the magneto hydrodynamic (MHD) formalism that combines the classical laws of fluid mechanics and electromagnetism. After a brief review of this formalism, several examples of electrically conducting fluids will be discussed. For instance, liquid metal flows are important in several industrial applications including the steel industry as well as in the description of geophysical flows and laboratory experiments on the dynamo effect. Also, plasmas represent an important class of electrically conductive fluids when they are treated in the limit of continuous media. Plasma physics is relevant in the study of various astrophysical systems as well as in laboratory experiments on magnetic confinement fusion. The importance of MHD effects for the ITER (International Thermonuclear Experimental Reactor) experiment will also be briefly discussed. Numerical simulations of the MHD equations play an increasingly important role in the description of electrically conducting fluids. Recent numerical results will be presented and MHD turbulence will be analyzed in terms of energy transfers, locality functions as well as sub grid scale modeling in large eddy simulations. S.12 George Throumoulopoulos: Introduction to Magnetohydrodynamics Department of Physics, University of Ioannina, Greece Basic components of plasma conˉnement in fusion devices as the tokamak are equilibrium and stability. In equilibrium the pressure gradient force acting on a plasma element is balanced by the magnetic force. Good confinement additionally requires stability for perturbations around an equilibrium state. The simplest model to study plasma confinement is magnetohydrodynamics (MHD). In the framework of MHD the plasma is described as a single fluid the physics of which is governed by electromagnetic interactions. In this talk the basic elements of the MHD model is first reviewed, then certain MHD equilibrium issues of magnetically conˉned plasmas are presented. In addition, some current research problems in connection with the ITER project are briefly outlined. S.13 Paraskevas Lalousis: Compressible MHD (ideal/resistive) Συμπιεστή Μαγνητοϋδροδυναμική (χωρίς/ με ηλεκτρική αντίσταση) Ινστ. Ηλεκτρονικής Δομής και Λέιζερ Ίδρυμα Τεχνολογίας & Έρευνας, Ηράκλειο, Κρήτη Η εξίσωση Boltzmann, για κάθε στοιχείο του πλάσματος, σε συνδυασμό με τις εξισώσεις του Maxwell περιγράφουν πλήρως τη δυναμική του πλάσματος. Η επίλυση των εξισώσεων αυτών (αναλυτικά ή υπολογιστικά) δεν είναι εφικτή. Μια καλή προσέγγιση είναι η Μαγνητοϋδροδυναμική (ΜΥΔ). Θα περιγράψουμε πώς παίρνοντας ροπές της εξίσωσης Boltzmann παράγουμε τις εξισώσεις διατήρησης μάζας, διατήρησης ορμή, και διατήρησης ενέργειάς της ΜΥΔ. Θα παράγουμε την γενική εξίσωση του Ohm's, και από αυτήν την εξίσωση θα περιγράψουμε τι είναι Ιδανική ΜΥΔ, ΜΥΔ με αντίσταση, ΜΥΔ Hall, και ΜΥΔ δυορευστών. Η εξίσωση Grad Shafranov, η οποία παράγεται από την εξίσωση ορμής της ΜΥΔ σε σταθερή κατάστασή, περιγράφει το πλάσμα και τα μαγνητικά πεδία σε ένα tokamak. Θα καταδείξουμε την αριθμητική επίλυσης της Grad Shafranov, με πεπερασμένες διαφορές και πεπερασμένα στοιχεία Επίσης θα παρουσιάσουμε τί είναι ΜΥΔ κρουστικά κύματα, και την αριθμητική επίλυσή των εξισώσεων της ΜΥΔ με ηλεκτρική αντίστασή σε πολλές διαστάσεις και χρονική εξέλιξη. S.14 Valentin Igochine: Introduction to plasma stability Max Planck Institute of Plasma Physics, Garching, Germany This introductory talk is aimed to give an overview of the stability problems in modern tokamaks. Starting from construction of a toroidal equilibrium we continue with energy principle. This allows understanding sources of instabilities, which limits operational space in modern tokamaks and in International Thermonuclear Experimental Reactor (ITER). The main part of the talk is dedicated to simple explanation of main MHD instabilities: Sawteeth Neoclassical Tearing Mode (NTM) Edge Localized Mode (ELM) Resistive Wall Mode (RWM) Fast particle instabilities. All these instabilities are subjects for intensive research in most fusion labs all over the world. They have also shown to be particularly important for ITER. Assuming student audience, the presentation does not require special knowledge in MHD and do not contain heavy mathematics. S.15 Valentin Igochine: Operational limits and MHD instabilities in modern tokamaks and ITER Max Planck Institute of Plasma Physics, Garching, Germany This overview talk focuses on main performance limiting instabilities in modern tokamak and in ITER. Starting from the operating space of tokamak we continue with discussion of main MHD stability problems which have 9/20

10 to be solved for ITER needs. The MHD phenomena which were identified to be crucial for ITER operations are following: Sawteeth Neoclassical Tearing Mode (NTM) Edge Localized Mode (ELM) Resistive Wall Mode (RWM) Toroidal Alfven Eigenmodes (TAEs) Disruption. Each of these problems could be addressed with several different techniques. Actually, multiple choices of possible solutions assure that the problem will be solved in ITER either by one of the developed techniques or by combination of several different approaches. S.16 Nikos Pelekasis: Introduction to hydrodynamic and MHD stability (Εισαγωγή στην υδροδυναμική και Μαγνητοϋδροδυναμική ευστάθεια) University of Thessaly, Volos, Greece Στοιχειώδης θεωρία ευστάθειας και θεωρία διακλαδώσεων: Γραμμική και ελαφρώς μη γραμμική ανάλυση, Παραδείγματα από κλασσική υδροδυναμική ευστάθεια, Υπολογιστική κατασκευή διαγραμμάτων διακλάδωσης Δυναμική σε χαμηλούς μαγνητικούς αριθμούς Reynolds: Μαγνητική απόσβεση Δημιουργία κίνησης, Οριακά στρώματα (Στρώματα Hartmann και πλαϊνά). Ευστάθεια μαγνητοϋδροδυναμικών ροών: Ευστάθεια στρωμάτων Hartmann και πλαϊνών στρωμάτων, Ροή υγρών μετάλλων σε σωλήνες Εξαναγκασμένη και ελεύθερη αγωγή, Εφαρμογές στο σχεδιασμό αντιδραστήρων πλάσματος WORKSHOP 2: MHD FLOWS AND PLASMA STABILITY W2.1 Leo Buehler, Chiara Mistrangelo: Analysis of liquid metal MHD flows in the European Test Blanket module Karlsruhe Institute of Technology, FZK, Karlsruhe, Germany Liquid metal magnetohydrodynamic flows in a scaled mock up of a helium cooled lead lithium (HCLL) test blanket module for the fusion reactor ITER have been investigated experimentally and numerically. The geometry is scaled down by a factor 2 compared to the original dimensions to fit into the gap of the large dipole magnet available in the MEKKA laboratory of the Karlsruhe Institute of Technology (formerly Forschungszentrum Karlsruhe), where sodium potassium (NaK) is used as model fluid. Pressure and electric potential on the surface of the mock up have been recorded for various magnetic field strengths and flow rates. The experiments confirm theoretical predictions according to which the major contributions to the total pressure drop arise in access pipes and manifolds. The experiments show that additional but smaller contributions are also present when the flow passes through the narrow gaps in the back plate or at the first wall. A pressure drop correlation has been derived that allows extrapolating the recorded data to ITER operating conditions for which the pressure drop in the blanket module is most likely inertialess. Results of electric potential measurements on the surface of the test section yield information about flow distribution in the mock up. A strong electrical coupling of the various flow domains results in sufficiently uniform flow distribution in the breeder units in accordance with numerical simulations. W2.2 Loukas Vlahos: Instabilities driven by energetic particles Department of Physics, University of Thessaloniki, Thessaloniki, Greece Sustained ignition of thermonuclear plasma depends on heating by highly energetic alpha particles produced from fusion reactions. Excess loss of the energetic particles may be caused by fishbone instability and toroidal Alfven eigenmodes induced by energetic particles. Such losses do not only reduce the alpha particle heating efficiency, but may also lead to excess heat loading and damage to plasma facing components. These problems have been studied in experiments and analyzed theoretically. In this short tutorial, I will introduce the main issues involved since the superthermal energe c par cles (EP) o en drive shear Alfvén waves unstable in magnetically confined plasmas. These instabilities constitute a fascinating nonlinear system where fluid and kinetic nonlinearities can appear on an equal footing. In addition to basic science, Alfvén instabilities are of practical importance, as the expulsion of energetic particles can damage the walls of a confinement device. W2.3 George Poulipoulis, George Throumoulopoulos, C. Konz*: Extending HELENA to equilbria with flow University of Ioannina, Ioannina, Greece * Max Planck Institute for Plasma Physics, Garching, Germany Sheared flows may improve the confinement properties of magnetically confined plasmas by playing a role in the creation of transport barriers either in the edge region (H mode) or within the plasma volume (Internal Transport Barriers). This is possibly related to the fact that such flows can affect the equilibrium properties [1] and cause stabilising effects [2]. Therefore, the understanding of plasma equilibria with flows is of interest to EFDA Task Force of Integrated Tokamak Modelling. Taking this into consideration, within the framework of the 2011 Workprogram we have initiated the extension of the equilibrium code HELENA [3] to include incompressible 10/20

11 flows. The study will be performed in two steps, the one concerning flows parallel to the magnetic field and the other flows of arbitrary direction. In the first case, the generalised Grad Shafranov equation governing the equilibria can be transformed via an integral transformation into the usual (static) form [4 5]. Therefore, the main task in extending HELENA for parallel flows is to implement the aforementioned transformation in order to calculate the physical quantities by means of the quantities involved in the existing version of the code. [1] S. Gunter, R.C. Wolf, F. Leuterer, O. Gruber, M. Kaufmann, K. Lackner, M. Maraschek, P.J. McCarthy, H. Meister, A. Peeters, G. Pereverzev, H.Salzmann, S. Schade, J. Schweinzer, W. Suttrop, and ASDEX Upgrade Team, Phys. Rev. Lett. 84, 3097 (2000) [2] G. N. Throumoulopoulos and H. Tasso, Phys. Plasmas 17, (2010) [3] G. T. A. Huysmans et al., Proc. CP90 Conf. Comp. Phys., 371 (1991) [4] H. Tasso and G. N. Throumoulopoulos, Phys Plasmas 5, 2378 (1998) [5] G. N. Throumoulopoulos, H. Tasso and G. Poulipoulis, J. Plasma Physics 74, 327, (2008) SCHOOL LECTURES (PLENARY SESSIONS: 9 10) S.17 Abhay Ram: Heating and current drive by radio frequency waves Massachusetts Inst. of Technology, USA Electromagnetic radio frequency waves occur naturally in terrestrial, space, and astrophysical plasmas. The waves are a consequence of collective motion of the plasma constituents. There is a rich diversity of electromagnetic waves in plasmas much more so than for waves in vacuum. The generation of waves in a laboratory plasma can be controlled by appropriately designed sources of electromagnetic radiation. Controlled thermonuclear magnetic fusion reactors have to operate in steady state at temperatures exceeding 200,000,000 degrees. Electromagnetic radio frequency waves, generated by external sources, can be used for heating the confined plasmas to the required temperatures, controlling instabilities, and for maintaining steady state operation. The variety of plasma waves allows for mixing and matching of different waves with the desired goals. S.18 Christos Tsironis: Modeling of electromagnetic wave propagation in tokamak devices and applications National Technical University of Athens Dept. Physics, Aristotle U. Thessaloniki, Greece In this lecture, the current status in the theory and experiments involving electromagnetic wave propagation in tokamaks is reviewed. Electron Cyclotron, Ion Cyclotron and Lower Hybrid Resonance Heating and Current Drive (EC/IC/LH H&CD) are nowadays well established methods for plasma heating and generation of noninductive current in modern fusion devices, with their present usage going beyond their heating and current drive application. For example, the control of magnetohydrodynamic (MHD) instabilities, the formation of Internal Transport Barriers (ITBs) and the high resolution achieved in wave diagnostics employ the advantage of the localized power deposition of EC waves. Wave propagation in tokamak plasma is described by Maxwell's equations and, in general, to obtain a full solution to the problem is very hard, because the wave equation is a partial differential equation (PDE) and also a constitutive relation for the plasma response must be determined. In situations where the wavelength is small compared to the scale length of plasma inhomogeneity, which is mostly the case in modern experiments, a simplification is achieved by using asymptotic methods where the solution is obtained through Hamiltonian ODEs. There are several ray/beam tracing codes that implement such methods, and the results obtained are in agreement with a number of transmission experiments from smaller tokamaks. However, in many cases of interest, like e.g. mode conversion or wave scattering by plasma turbulence, this approach may break down, the solution becomes questionable and a full wave analysis is necessary. Full wave codes available today are computationally expensive implementations of finite differences/elements and spectral/pseudospectral methods. S.19 Jean Philippe Hogge: A Gyrotron overview Ecole Polytecnique Federale de Lausanne, Switzerland Gyrotrons are microwave sources able to deliver power ranging from a few watts up to the megawatt level, at frequencies extending from a few GHz up to hundreds of GHz, with an efficiency which can be as high as 50% Their simplicity makes them very robust. They find their main application in fusion devices such as tokamaks or stellarators, where they can be used to perform bulk heating of the plasma, generate current in a non inductive way, control instabilities, among others. The basic principles of the gyrotron interaction theory will be reviewed, and a description of some important components will be given. S.20 Edith Borie: Simulation of RF behavior in the gyrotron cavity Karlsruhe Institute of Technology, FZK, Karlsruhe, Germany 11/20

12 WORKSHOP 3: GYROTRONS ELECTRON CYCLOTRON RESONANCE HEATING W3.1 Jean Philippe Hogge: Gyrotrons for the ITER ECRH System Ecole Polytecnique Federale de Lausanne, Switzerland In order to fulfill its commitment to deliver 8MW of RF power at 170GHz to ITER, the EU has launched an ambitious program aiming at the development of a 2MW Coaxial Gyrotron. The program started in 2003 and foresees the manufacture of three prototypes with target performances of 2MW/1s/60s/3600s respectively. The first prototype was extensively tested in 2008 in the newly built European Gyrotron Test Stand. An account of the results and their interpretation will be given. The tube will be opened and refurbished, allowing the installation and the tests of improved components, before launching the second phase of the project. W3.2 Edith Borie: Development of 140 GHz, 1MW CW gyrotrons for fusion applications Progress and recent results Karlsruhe Institute of Technology (FZK), Karlsruhe Germany W3.3 Kostas Avramides: Gyrotron interaction simulations with tapered magnetostatic field National Technical University of Athens, Greece High power gyrotrons are the leading microwave sources for plasma heating and current drive in magnetic confinement fusion experiments. In a gyrotron, a helical electron beam, formed by a MIG type electron gun and guided by an external magnetostatic field, delivers energy to a RF electromagnetic wave (i.e. a TE mode supported by the interaction cavity) through electron cyclotron resonance. Numerical simulations of the beamwave interaction in high power gyrotrons are the basic tool for the design of the interaction cavity in these devices. In order for the interaction codes to be used efficiently as designing tools undertaking detailed parameter studies, fast simulations are necessary. Several simplifying assumptions are thus employed in the interaction codes, to make them capable of fast calculations. However, as the resonators get larger to meet the increasing needs in output power and their mode spectrum becomes denser, the validity of some of the aforementioned assumptions needs to be revisited. We discuss the modelling of the beam wave interaction, focusing on the adopted assumptions. In addition, we present results from investigations on the influence of these simplifying assumptions on the electron trajectories, using two pertinent numerical codes: (1) EURIDICE, which is based on the slow time scale approximation for the electron motion and also on further assumptions, widely used in similar fast interaction codes, and (2) Ariadne++, which, contrary to EURIDICE, uses no approximations when calculating the electron motion in a given electromagnetic field. W3.4 George Anastasiou: Power enhancement of the Gaussian RF beam of a gyrotron National Technical University of Athens, Greece W3.5 Ioannis Tigelis: Recent numerical results for gyrotron beam tunnels by CST Department of Physics, National University of Athens, Athens, Greece W3.6 Marina Moraitou: Numerical results for TE and hybrid modes in corrugated coaxial wave guides Department of Physics, National University of Athens, Athens, Greece W3.7 Stavros Moustaizis, Paraskevas Lalousis*: Progress on compact magnetic fusion devices: initiative for a neutron test facility Lab of Matter Structure and Laser Physics, Technical University of Crete, Chania, Greece * Institute of Electronic Structure and Laser FORTH, Heraklio, Crete, Greece A two dimensional resistive MHD code in axisymmetric cylindrical geometry has been developed, which solves the conservation equations for mass, momentum and energy of plasmas coupled with the magnetic field equations. The code can handle very large magnetic fields and very steep gradients of the plasma parameters; the code is applied to study very high density plasmas in a compact fusion device with mirror like magnetic field. Numerical studies of high density, high temperature plasma, in a compact fusion device with an external 12/20

13 applied mirror like magnetic configuration, enables to optimize the neutron flux production and improve the trapping time of the plasma. These investigations allow the development of a Neutron Test Facility for Tokamak blanket material studies. SCHOOL LECTURES (PLENARY SESSIONS: 9 10) S.21 Stavros Moustaizis: Negative ions Neutral beams and potential applications to magnetic fusion Lab of Matter Structure and Laser Physics, Technical University of Crete, Chania, Greece We present a new source of negative ion (H and/or D) production, from laser cluster and/or laser deuterteted gas interaction. The main advantages of the proposed alternative source are (a) the high density of the produced negative ions and (b) the relatively small volume of production. Such a source can be placed at the end of a pulsed power generator working at 1 MeV and producing a current of negative ion beam up to 500A 1kA. The proposed negative ion source and acceleration scheme is based on the development of a magnetically isolated diode capable to produce a pulsed negative ion beam with kinetic energy up to 1 MeV and a current of A. Calculations on a laser based negative ion neutralizer enable to propose a laser cavity of approximately 2 m to neutralize the pulsed negative ion beam. Three different laser systems were considered in order to evaluate their efficiency on the neutralization of the negative ion beam in order to develop a compact laser based negative ion beam neutralizer for Tokamak plasma heating applications. S.22 Grigoris Haidemenopoulos, Alexis Kermanidis: Materials at high temperatures Department of Mechanical Engineering, University of Thessaly, Volos, Greece In many engineering applications, materials are facing high temperatures, usually above half the melting point, for extended periods of time. The mechanical behavior under these conditions determines the structural integrity of engineering components while in several cases the development of certain new technologies is limited by the development of materials. In the present lecture the basic principles of the mechanical behavior of materials at high temperatures are presented with emphasis on time dependent deformation, i.e. creep. The mechanisms for creep deformation and creep fracture are analyzed and the criteria for high temperature resistance, such as the melting point, the maximum service temperature and thermal distortion are discussed. Finally the basic characteristics of heat resistant materials are presented such as ferritic, martensitic and austenitic stainless steels, refractory metals and alloys, intermetallics, ceramic matrix composites as well as carbon carbon composites. Γ.Ν. Χαϊδεμενόπουλος, A. Κερμανίδης: Τα Υλικά σε Υψηλές Θερμοκρασίες Τμήμα Μηχανολόγων Μηχανικών Πανεπιστήμιο Θεσσαλίας Σε πολλές μηχανολογικές εφαρμογές τα υλικά καλούνται να αντιμετωπίσουν υψηλές θερμοκρασίες, συνήθως πάνω από το ½ του σημείου τήξεως, για μεγάλα χρονικά διαστήματα. Η μηχανική συμπεριφορά των υλικών στις συνθήκες αυτές καθορίζει την δομική ακεραιότητα και λειτουργικότητα των μηχανολογικών διατάξεων και σε πολλές περιπτώσεις η ανάπτυξη συγκεκριμένων τεχνολογιών περιορίζεται από την αντίστοιχη ανάπτυξη των υλικών. Στην παρούσα διάλεξη παρουσιάζονται οι βασικές πτυχές της μηχανικής συμπεριφοράς σε υψηλές θερμοκρασίες, με έμφαση στη χρονικά εξαρτημένη παραμόρφωση, δηλαδή στον ερπυσμό. Αναλύονται οι μηχανισμοί του ερπυσμού και προσδιορίζεται η επίδραση της μικροδομής του υλικού. Επίσης παρουσιάζεται το πρόβλημα της θραύσεως σε υψηλές θερμοκρασίες. Στη συνέχεια αναλύονται τα κριτήρια τα οποία πρέπει να ικανοποιεί ένα υλικό για να αντέχει σε υψηλές θερμοκρασίες, όπως το σημείο τήξεως, η μέγιστη θερμοκρασία λειτουργίας και η θερμική παραμόρφωση. Στο τέλος παρουσιάζονται τα βασικά χαρακτηριστικά των υλικών με αντοχή σε υψηλές θερμοκρασίες, όπως: φερριτικοί/μαρτενσιτικοί/ωστενιτικοί ανοξείδωτοι χάλυβες (stainless steels), υπερκράματα νικελίου (superalloys), πυρίμαχα μέταλλα και κράματα (refractory metals), ενδομεταλλικές ενώσεις (intermetallics), κεραμικά υλικά και σύνθετα υλικά με κεραμική μήτρα (ceramic matrix composites), σύνθετα υλικά με βάση τον άνθρακα (carbon carbon composites). S.23 Panagiotis Grammatikopoulos: Fusion relevant materials: Problems and prospectives National Centre for Scientific Research Demokritos, Athens, Greece For commercial fusion reactors (CFRs) to be achieved, a number of experimental ones have either been or are being developed. Today, one of the most ambitious projects worldwide is ITER, now being constructed in Cadarache, France. Although ITER is designed to be very close to a CFR, once it is finished and before the operation of a CFR, another demonstration reactor, DEMO, is proposed, with objectives extending those of ITER. 13/20

14 During both projects, one of the major challenges the fusion scientific community will have to face is the development of materials of adequate strength, toughness, and swelling and creep resistance which will be able to operate under CFR conditions. Temperatures up to 600 o C, stresses up to 300 MPa and fast neutron radiation damage of the order of 100 displacements per atom (dpa) will be typical for first wall operation. Other than that, the choice of materials for a fusion power plant is limited by demands in availability, good mechanical and fabrication properties, reliability, demand for no extremely long lived isotopes, etc. A number of materials have been proposed so far that might withstand such extreme conditions and fulfil such demanding criteria, based on experience from previous fusion plant projects. Such materials are mainly ferritic martensitic steels, beryllium, tungsten and vanadium alloys, while recently considered ones include carbon fibre/carbon composites, and high strength dispersion hardened copper. This presentation will focus on the physical processes of radiation damage and how the endeavour to minimise this damage dictates the choice of materials for various particular fusion reactor components. Main concepts of materials science will be introduced and basic research methods will be touched upon; in particular, fusion materials related research activities of the Hellenic association in Demokritos. MINI SYMPOSIUM: MODELING VACUUM FLOWS, VISCOUS MHD, TURBULENCE AND HEAT TRANSFER MS00 Panagiotis Grammatikopoulos: Computer simulation of dislocation interaction with radiation induced obstacles in iron National Centre for Scientific Research Demokritos, Athens, Greece Assessment of candidate materials for fusion power plants provide one of the major structural materials challenges for the next decades. Computer simulation provides a useful alternative to experiments on real life irradiated materials. Within the framework of a multi scale modelling approach, atomic scale studies by molecular dynamics (MD) and statics (MS) are of importance since they enable understanding of atomic interaction mechanisms invisible at coarser scales. Nano scale defect clusters, such as voids and solute atom precipitates can form in metals irradiated by high energy atomic particles. Since they are obstacles to dislocation glide, they can affect plasticity, substantially changing the yield and flow stresses and ductility. In the study presented here, a model has been used, that enables dislocation motion under applied shear strain at various temperatures and strain rates. Extensive atomic scale computer simulations have shown that nanoscale voids and copper precipitates can be strong obstacles to the glide of dislocations in neutron irradiated iron. In the case of voids, an edge dislocation climbs by absorbing vacancies as it breaks away. The obstacle strength of copper precipitates, on the other hand, is associated with a dislocation induced structural transformation of the copper if they are large enough and the temperature is low enough. Most of the reported simulations have placed the centre of a spherical void or precipitate on the slip plane of an edge dislocation. The present work has been undertaken to investigate how the obstacle strength of 2 and 4 nm voids and precipitates varies with the distance of their centre for the slip plane at temperatures across the range 0 to 450 K. The strength of voids is highest when their centre coincides with the slip plane, but this is not the case for small precipitates, which do not transform from the bcc structure. The strength of both types of obstacle and the extent of climb at voids and transformation of large precipitates are not symmetric with respect to distance of their centre above or below the slip plane. These results are discussed in terms of the atomic mechanisms involved and the consequences for continuum treatment of irradiation hardening. MS01 Daniele Carati: Particle tracking in MHD turbulence Physique Statistique et Plasmas, Université Libre de Bruxelles A general numeric approach is proposed to follow particle trajectories in the presence of turbulent fields. Although the method can be adapted to a wide variety of physical problems, its application is focused here on the study of charged particle transport in turbulent plasmas. The major difficulty of the method is to combine the simulation of Lagrangian particle trajectories with the Eulerian computation of the turbulent fields that influence the particle motion. The particular case of charged particles submitted to turbulent electromagnetic fields generated on a grid by a nonlinear magnetohydrodynamic (MHD) solver will be discussed. The interplay between the Lagrangian particle trajectory solver and the interpolation scheme needed for estimating the turbulent fields between the grid points will be emphasized. The MHD flow that has been retained corresponds to the Kolmogorov forcing. The flow is driven by a constant force acting in one direction and varying periodically in space in a direction perpendicular to itself. Such a flow will be shown to develop a turbulent regime with long standing large scale structures. Transport properties, such as the mean squared displacements and probability density functions, of charged particles in the Kolmogorov flow will be presented. 14/20

15 MS02 Chris Dritselis, Nicholas Vlachos: MHD turbulent channel flow with heat transfer Dept. of Mechanical Engineering, University of Thessaly, Volos, Greece A numerical study is carried out of the magnetic field effects on the coherent structures and the associated heat transfer in a turbulent channel flow with constant temperature at the bottom (cold) and top (hot) walls. Results from direct numerical simulations are conditionally sampled in order to extract the dominant coherent structures in the near wall region for flows with and without a uniform external magnetic field in the wallnormal direction. The Reynolds number based on the bulk velocity and the wall distance is 5600, while only a representative small Stuart number of 0.01 is explored. Two fluids with Prandtl numbers of 0.01 and 0.71 are studied. It is shown that the conditionally averaged quasi streamwise vortices are modified by the magnetic field with their size being increased and their strength decreased. The underlying organized fluid motions are damped by the Lorentz force and the turbulent heat transfer related to the action of quasi streamwise vortices is decreased by the magnetic field. For the higher Prandtl number fluid, a similarity between the coherent temperature and the coherent streamwise velocity fluctuations is observed for both types of flow. This is diminished for the lower Prandtl number fluid, especially in the magnetohydrodynamic flow, inhibiting the intrusion of cold (hot) fluid from the cold (hot) wall towards the central region. MS03 Sarantis Pantazis, Serafim Misdanitis, Demitris Valougeorgis: Simulation of non linear flows under any vacuum conditions Department of Mechanical Engineering, University of Thessaly, Volos, Greece The flow of rarefied gases through channels of finite length driven by arbitrarily large gradients of pressure is studied. In particular, we are interested in flow through short planar or cylindrical channels or through an expansion/contraction element, composed of two tube elements of different diameters, connected in series. These geometries are frequently encountered in the pumping system and other vacuum components of fusion reactors. Extensive work is available in the viscous regime, but the literature is quite limited under vacuum conditions. Two methodologies are available for conditions far from local thermodynamic equilibrium: the numerical solution of the non linear Boltzmann equation, where the collision term has been substituted by an appropriate kinetic model to reduce the complexity, or the Direct Simulation Monte Carlo (DSMC) method. In both cases, significant computational effort is involved for the current problems, since the phase space is 4 or 5 dimensional. Results of high accuracy, including bulk quantities of practical interest, such as channel conductance, as well as distributions of density, temperature and velocity, are provided within a reasonable amount of time in the whole range of the Knudsen number. Methods of convergence acceleration for small Knudsen flows and computational efficiency issues are also discussed. MS04 John Lihnaropoulos, Demitris Valougeorgis: Transient vacuum gas flows through cylindrical ducts Department of Mechanical Engineering, University of Thessaly, Greece The starting gas flow in a cylindrical duct is investigated in the whole range of the Knudsen number by numerically solving the governing time dependent kinetic equations in a fully deterministic manner. The gas is initially at rest and then due to a suddenly imposed uniform pressure gradient, is starting to flow. The motion is time dependent up to the point where the steady state flow conditions are recovered. The flow field is modelled by the linearized unsteady BGK equation subject to Maxwell purely diffuse boundary conditions. The solution provides a detailed description of the evolution of the flow field with regard to time from the starting point, where the gas is at rest up to a certain time where almost steady state conditions are recovered. Based on the results some insight of how rapidly a vacuum flow will respond to a sudden change, related to an externally imposed pressure gradient coming from a vacuum pump or a valve, is obtained. The total time to recover the stationary solution in terms of the rarefaction parameter exhibits a minimum close to the wellknown Knudsen minimum. MS05 Paraskevas Lalousis: Fuelling of fusion reactors Institute of Electronic Structure and Laser FORTH, Heraklio, Crete, Greece MS06 Antonis Sergis: Anomalous heat transfer modes of nanofluids: A review based on statistical analysis Department of Mechanical Engineering, Imperial College, University of London, 15/20

16 MS07 Serafim Misdanitis, Demitris Valougeorgis: Design of gas distribution systems consisting of long tubes under any vacuum conditions Department of Mechanical Engineering, University of Thessaly, Volos, Greece Rarefied gas flows through single long channels of various cross sections have been extensively investigated over the years both numerically and experimentally. It has been shown that for low speed flows, which is commonly the case when the ratio of the length over the radius of the channel is adequately large, the most suitable approach to efficiently solve the problem in the whole range of the Knudsen number is linear kinetic theory. In fusion related vacuum applications, including the vacuum systems of DT reactors, these single channels are combined together in order to form a pipe network. In the present work a first attempt to deal with this problem is performed. In particular a systematic computational approach is presented for the design of pipe networks consisting of long tubes. This is achieved by successfully integrating the kinetic results obtained for the rarefied flow through each tube of the network into a typical network algorithm solving the whole distribution system. Once the geometry of the network is fixed, the integrated algorithm may successfully handle gas pipe networks of any complexity operating under any rarefied conditions from the free molecular, through the transition up to the slip and hydrodynamic regimes. A typical piping system is simulated to demonstrate the feasibility of the approach. MS08 Dimitris Dimopoulos, Nikos Pelekasis: Magnetic field effects on 3D stability of natural convection in differentially heated cavities Department of Mechanical Engineering, University of Thessaly, Volos, Greece The parametric study of two dimensional free convection flow in a square cavity is extended in order to cover three dimensional disturbances. Identification of the mechanism for generation of quasi two dimensional structures is also attempted in ducts where Rayleigh Bernard convection takes place. The parametric study of two dimensional free convection flow in a square cavity is extended in order to cover three dimensional disturbances. The magnetic field is taken to be perpendicular to gravity, in the cavity cross section. Mass continuity and the momentum, energy and electric charge conservation equations are solved for. The Galerkin finite element method is used for calculating the two dimensional steady state and discretizing the linear stability problem, in the param eter space defined by the dimensionless numbers, Gr, Ha, Pr, volumetric heat production, and aspect ratio of the cross section. The Arnoldi method is used for the calculation of eigenvalues with the highest absolute value. Parametric continuation is performed via the GMRES method in order to obtain the evolution of specific critical modes as k, Gr. First, a temperature gradient parallel to the Hartmann walls is assumed. In all cases examined three dimensional disturbances are less stable than two dimensional ones, while increasing the Ha number increases critical Gr as well. A travelling and a standing wave arise as dominant eigenmodes as a result of centrifugal instability due to the curvature 1 of the stream lines in the base flow 2. A parametric study is performed in order to identify the effect of the magnetic field, increasing Ha, on the direction and strength of the emerging recirculation vortices as the aspect ratio of the cavity varies. [1] N. Pelekasis, Linear Stability Analysis and dynamic simulations of free convection in a differentially heated cavity in the presence of a horizontal magnetic field and a uniform heat source, Phys. Fluids 18, (2006). [2] P.G. Drazin, W. H. Reid Hydrodynamic stability, Cambridge University Press MS09 Sotiris Kakarantzas, Bernard Knaepen: Simulation and modelling of the IFMIF Lithium target flow Universite Libre de Bruxelles, Physique Statistique et Plasmas, Brussels, Belgium In recent years, worldwide energy demand has increased significantly. Among the few possible new energy supplies, thermonuclear fusion is one of the most promising options in terms of sustainability, environmental acceptability and safety. Therefore, a big scientific effort is undertaken in the design of future fusion power plants. Among the challenges, one of the key problems is the choice of structural materials that can be subjected for a long time to an intense neutron irradiation load. In order to test candidate materials and irradiate specimens EURATOM and Japan have decided in 2007, within the Broader Approach agreement [1], to design an International Fusion Materials Irradiation Facility (IFMIF). In IFMIF two deuteron beams, of 40 Mev, will be deposited into a high speed liquid Lithium (Li) jet, flowing in a vacuum environment along a vertical concave wall, to produce an intense neutron flux which will be used to irradiate materials specimens and test components. In order to remove the large deposited beam energy, which is up to 10 MW, high Li velocities (up to 20m/s) are needed [2]. In parallel, the fluctuations of the Li flow must be limited to less than 1mm as they could have significant ill effects on the neutron field. The simulations of working conditions with the available engineering CFD codes are part of the design work and the results will be used to confirm the appropriateness and possibly to improve the proposed construction. ULB in collaboration with ENEA is responsible for performing a parametric numerical study of the design and for providing a validation for the choice of the optimal flow parameters [3]. 16/20

17 1. Agreement between the European Atomic Energy Community and the Government of Japan for the Joint Implementation of the Broader Approach Activities in the Field of Fusion Energy Research, Official Journal of European Union, L 246/34, H. Nakamura, P. Agostini, K. Ara, S. Fukada, K. Furuya, P. Garin, A. Gessi, D. Giusti, F. Groeschel, H. Horiike, M. Ida, T. Kanenmura, H. Kondo, N. Loginov, G. Micciche, M. Miyashita, F.S. Nitti, A. Suzuki, T. Terai, K. Watanabe, J. Yagi, E. Yoshida and A. Mikheyev, Status of engineering design of liquid lithium target in IFMIF EVEDA, Fusion Eng. & Design, 84 (2009), Engineering Validation and Engineering Design Activities for the International Fusion Materials Irradiation Facility, PA LF06 Annex B: Technical Specification for the Engineering Design of the IFMIF Lithium Target Facility. MS10 Alexandros Iatridis, Ioannis Sarris, Nicholas Vlachos: Direct numerical simulation of magnetohydrodynamic flow in toroidal ducts Department of Mechanical Engineering, University of Thessaly, Greece MS11 Ioannis Sarris, Daniele Carati*: Large eddy simulation of non equilibrium Kolmogorov flow in the presence of external magnetic fields Department of Mechanical Engineering, University of Thessaly, Volos, Greece * Plasma Physique et Statistique, Université Libre de Bruxelles In the recent numerical work of Sarris et al. [Phys. Fluids 19, (2007)], new features of the turbulent Kolmogorov flow were found for elongated periodic domains. It is known now that, when the computational domain is reduced in a cubic box, the velocity statistics exhibit symmetries that are directly imposed by the forcing properties. However, for larger domains, the translational invariance in the streamwise direction appears to be broken and the turbulent statistics are found to depend on the aspect ratio of the computational box. In the light of the new findings, the Kolmogorov flow is studied here in the frame of statistical ensemble large eddy simulations. In particular, statistics of an ensemble of up to 96 independent simultaneous simulations of the flow was collected. The only communication permited between the simulations was made during the determination of the dynamic Smagorinsky model constant C which is evaluated and averaged only between the ensemble. In contrast to the usual practice of large eddy simulations of homogeneous turbulence, no local averaging in the spatial directions of each simulation is allowed. The simulation in each instance was initiated either from random or suitably chosen large eddy simulations or filtered velocity fields from direct numerical simulations. The results were found to be sensitive to the initial conditions in the sense that the dominant statistical flow structure may be found as in direct numerical simulations or may arise by the averaging between the ensemble. The study is also extended to the non equilibrium case where the turbulent flow is affected by the imposed of large scale magnetic fields. The mean dominant structures and their deformation is been reconstructed by the ensemble process. POSTERS OF RESEARCH ACTIVITIES RP.01 I. Arapoglou, G. N. Throumoulopoulos, H. Tasso*: Paramagnetic Solovev equilibrium University of Ioannina, Ioannina, Greece * Max Planck Institut fuer Plasmaphysik, Garching, Germany A paramagnetic solution to the Grad Shafranov equation is constructed for pressure and poloidal current functions linear in the poloidal flux function u. Unlike the usual D shaped diamagnetic solution, the separatrix of the paramagnetic configuration has a corner on the origin of the cylindrical coordinate system (z,r,θ) similar to the nonlinear Palumbo isodynamic equilibrium configuration. The solution is extended to incompressible ows of arbitrary direction described by a generalized Grad Shafranov equation [1,2]. As in the case of the respective diamagnetic solution [2] the component of ow non parallel to the magnetic field associated with the quantity λ = d/du[ρ (dφ/du) 2 ] (here ρ(u) is the plasma density and Φ(u) the electrostatic potential) results in a variety of novel configurations in connection with a second ow depended stagnation point. This depends on the sign of λ irrespective of the magnitude of λ, a result clearly indicating that fusion relevant sheared ows can change the equilibrium magnetic field topology. [1] H. Tasso, G. N. Throumoulopoulos, Phys. Plasmas 5, 2378 (1998) [2] Ch. Simintzis, G. N. Throumoulopoulos, G. Pantis, H. Tasso, Phys. Plasmas 8, 2641 (2001) RP02 E.Benos, I.E. Sarris, N. Vlachos: Numerical modeling of plasma flows using the CFD library OpenFoam Department of Mechanical Engineering, University of Thessaly, Volos, Greece A fully 3 D CFD model is being developed to solve numerically the full non linear and compressible MHD equations. The new code is based on the OpenFOAM libray. The grids are generated to fit theiter like toroidal geometry. Except of the simpler MHD plasma flows, validation of the new numerical model with existing data from a sawtooth instability are being considered. 17/20

18 RP03 C. Dritselis, I. Sarris, D. Fidaros, N. Vlachos: Transport and deposition of neutral particles in MHD turbulent channel flows at low Rm Department of Mechanical Engineering, University of Thessaly, Volos, Greece The effect of Lorentz force on particle transport and deposition is studied by using direct numerical simulation of turbulent channel flow of electrically conducting fluids combined with discrete particle simulation of the trajectories of uncharged, spherical particles. The magnetohydrodynamic equations for fluid flows at low magnetic Reynolds numbers are adopted. The particle motion is determined by the drag, added mass, and pressure gradient forces. Results are obtained for flows with particle ensembles of various densities and diameters in the presence of streamwise, wall normal or spanwise magnetic fields. It is found that the particle dispersion in the wall normal and spanwise directions is decreased due to the changes of the underlying fluid turbulence by the Lorentz force, while it is increased in the streamwise direction. The particle accumulation in the near wall region is diminished in the magnetohydrodynamic flows. In addition, the tendency of small inertia particles to concentrate preferentially in the low speed streaks near the walls is strengthened with increasing Hartmann number. The particle transport by turbophoretic drift and turbulent diffusion is damped by the magnetic field and, consequently, particle deposition is reduced. RP04 H. Isliker, D. Constantinescu, L. Vlahos: Fractional transport equations and their numerical solution Department of Physics, Aristotle University of Thessaloniki Fractional transport equations can be derived from a state space conservation law in integral form, which actually describes a random walk process. Fractional derivatives appear naturally in the fluid limit when nonlocalities are explicitly allowed by making use of Levy distributions in the conservation law, which, in the random walk picture, corresponds to Levy walks in state space. In order to solve the fractional transport equation numerically, we use the Grunwald Letnikov definition of fractional derivative, in combination with a standard method for the time stepping. In an application, we consider the case of an off axis source term, and we show under which prerequisites the fractional transport equation is able to describe anomalous transport phenomena, such as transport against the driving gradient ('uphill' transport). RP05 S. Kakarantzas, I. Sarris*, N. Vlachos*: Natural convection of a liquid metal in a vertical annulus with lateral and volumetric heating in the presence of an horizontalmagnetic field Physique Statistique et Plasmas, Universite Libre de Bruxelles, Brussels, Belgium *Department of Mechanical Engineering, University of Thessaly, Volos, Greece MHD free convection of a liquid metal is studied in a closed vertical annulus in which the upper and bottom surfaces are adiabatic while the cylindrical walls are kept isothermal at different temperatures. The flow is driven by two mechanisms, the temperature difference between the inner and the outer cylindrical walls and the volumetric heating. An external horizontal magnetic field is also imposed resisting the fluid motion. The laminar and turbulent regimes of the flow are assessed by performing three dimensional direct numerical simulations. The results show that in the absence of the magnetic field, turbulent flow is developed in most of the cases while as the magnetic field increases the flow becomes laminar. The highest temperature is found in the upper central part of the annular cavity when the fluid is heated volumetrically, resulting in the creation of two convection currents as the hot fluid ascends in the central part and descends close to both colder walls. The Hartmann and Roberts layers developing near the walls normal and parallel to the magnetic field, respectively, are found to be responsible for the loss of axisymmetry of the present flow. RP06 S. Pantazis, S. Varoutis, V. Hauer*, C. Day*. D. Valougeorgis: Gas surface scattering effect on vacuum gas flows through rectangular channels Department of Mechanical Engineering, University of Thessaly, Volos, Greece *Karlsruhe Institute of Technology, Institute for Technical Physics, Germany RP07 K. Perrakis, S. Moustaizis: Production of negative ion beam (H D) and development of neutral beam using laser technology for applications in tokamaks Lab of Matter Structure and Laser Physics, Technical University of Crete, Chania, Greece 18/20

19 RP08 Th. Pisokas, H. Isliker, L. Vlahos: CHET1: a CHEbyshev pseudospectral code solving transport problems Department of Physics, Aristotle University of Thessaloniki, Greece Our aim is to develop a general code to solve the Fokker Planck equation, with both the drift coefficient and the diffusion coefficient depending on spatial variables and time. We apply the method of lines. We choose the Chebyshev collocation method to discretize the space and the fourth fifth order Runge Kutta embedded scheme (adaptive stepsize adjustment), using the Dormand Prince coefficients, to integrate over the time dimension. Note that the latter is realized in the physical, and not the Chebyshev, space. We describe the development of the algorithm and we present an application to the quasi linear diffusion. RP09 I. Sarris, D. Grigoriadis*, N. Vlachos: Laminar free convection in a square enclosure driven by the Lorentz force Department of Mechanical Engineering, University of Thessaly, Volos, Greece * Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus A numerical study is presented of laminar free convection flow driven by magnetic forces. An external magnetic field with one spatially varying component is applied to an electrically conducting fluid in a square enclosure. This magnetically driven flow is controlled by the intensity and the wave number of the applied magnetic forcing. In addition, when the enclosure is laterally heated in a non zero gravity environment, the resulting buoyant forces may contribute or resist the magnetically driven fluid motion. The present results show that a strong magnetic field can even reverse the buoyant flow. The circulation intensity of the flow and the heat transfer from the sidewalls is increased with increasing magnetic field or with decreasing magnetic Reynolds number. The wave number of the magnetic forcing is also an important parameter that determines the vortex patterns and consequently the convection heat transfer. RP10 I. Sarris, A. Iatrides, C. Dritselis, N. Vlachos: Magnetic field effect on the cooling of low Pr fluids in a vertical cylinder Department of Mechanical Engineering, University of Thessaly, Volos, Greece RP11 H. Tasso*, G. Throumoulopoulos: A comparison of Vlasov with drift kinetic and gyrokinetic theories Theoretical Physics, University of Ioannina, Greece *Max Planck Inst. for Plasma Physics, Garching, Germany A kinetic consideration of an axisymmetric equilibrium with vanishing electric field near the magnetic axis shows that f should not vanish on axis within the framework of Vlasov theory while it can either vanish or not in the framework of both a drift kinetic and a gyrokinetic theories (f is either the pertinent particle or the guiding center distribution function). This different behavior, relating to the reduction of phase space which leads to the loss of a Vlasov constant of motion, may result in the construction of different currents in the reduced phase space than the Vlasov ones. This conclusion is indicative of some limitation on the implications of reduced kinetic theories in particular as concerns the physics of energetic particles in the central region of magnetically confined plasmas. RP12 A. Xagoni, K. Hizanidis: Neutron stars magneto hydro dynamics National Technical University of Athens, Greece We present, for the first time, the structure of the axisymmetric force free magnetosphere of an aligned rotating magnetic dipole, in the case in which there exists a sufficiently large charge density (whose origin we do not question) to satisfy the ideal MHD condition, E B = 0, everywhere. The unique distribution of electric current along the open magnetic field lines which is required for the solution to be continuous and smooth is obtained numerically. With the geometry of the field lines thus determined we compute the dynamics of the associated MHD wind. The main result is that the relativistic outflow contained in the magnetosphere is not accelerated to the extremely relativistic energies required for the flow to generate gamma rays. 19/20

20 Dr Anastasios Anastasiadis National Observatory of Athens, Greece Dr George Anastasiou National Technical University of Athens, Greece Dr Kostas Avramides National Technical University of Athens, Greece Prof. Vasilis Bontozoglou Vice Rector, University of Thessaly, Greece Dr Eidth Borie Karlsruhe Institute of Technology, FZK, Germany Dr Leo Buehler Karlsruhe Institute of Technology, FZK, Germany Prof. Daniele Carati Inst. Plasma Physique, Univ. Libre Bruxelles, Belgium Dr Christian Day Karlsruhe Institute of Technology, FZK, Germany Mr Dimitris Dimopoulos University of Thessaly, Volos, Greece Dr Chris Dritselis University of Thessaly, Volos, Greece Dr Ruggerro Giannella DG Research, European Commission, Brussels Belgium Dr Panagiotis Grammatikopoulos NCSR Demokritos, Athens, Greece Dr Alkis Grecos University of Thessaly, Volos, Greece Prof. Grigoris Haidemenopoulos University of Thessaly, Volos, Greece Prof. Kyriakos Hizanidis National Technical University of Athens, Greece Dr Jean Philippe Hogge Ecole Polytecnique Fed. de Lausanne, Switzerland Mr Alexandros Iatridis University of Thessaly, Volos, Greece Dr Valentin Igochine Max Planck Inst. Plasmaphysics, Garching, Germany Dr Heinz Isliker Aristotle University of Thessaloniki, Greece Dr Sotiris Kakarantzas Inst. Plasma Physique, Univ. Libre Bruxelles, Belgium Dr Alexis Kermanidis University of Thessaly, Volos, Greece Dr Ioannis Kominis Natl. Technical Univ. of Athens, Greece Dr C. Konz Max Planck Inst. Plasmaphysics, Garching, Germany 10 TH SCHOOL OF FUSION PHYSICS & TECHNOLOGY UUnni iivveer rsi iit tyy oof f TThhees ssaal llyy,,, VVool lloos s GGr reeeeccee,,, MAAYY AUTHORS / SPEAKERS Prof. Zisis Kotionis Dean Engineering, University of Thessaly, Greece Dr Paraskevas Lalousis Foundation Research & Technology, Chania, Greece Dr George Latsas National University of Athens, Greece Mr John Lihnaropoulos University of Thessaly, Volos, Greece Mr Serafim Misdanitis University of Thessaly, Volos, Greece Miss Marina Moraitou National University of Athens, Greece Prof. Stavros Moustaizis Tech. University of Crete, Chania, Greece Mr Sarantis Pantazis University of Thessaly, Volos, Greece Dr Ioannis Papazoglou NCSR Demokritos, Athens, Greece Prof. Nikos Pelekasis University of Thessaly, Volos, Greece Dr George Poulipoulis University of Ioannina, Greece Prof. Abhay Ram Massachusetts Inst. Technology, PSFC, USA Dr Ioannis Sarris University of Thessaly, Volos, Greece Mr Antonis Sergis Imperial College, University of London, England Prof. Ioannis Tigelis National University of Athens, Greece Prof. George Throumoulopoulos University of Ioannina, Greece Dr Christos Tsironis Nat. Tech. U. Athens & Aristotle U. Thessaloniki, Greece Prof. Demitris Valougeorgis University of Thessaly, Volos, Greece Prof. Dionysis Vavougios University of Thessaly, Volos, Greece Prof. Nicholas Vlachos University of Thessaly, Volos, Greece Prof. Loukas Vlahos Aristotle University of Thessaloniki, Greece Prof. John Vomvoridis Natl Technical University Athens, Greece I. Arapoglou Univ. of Ioannina, Greece E. Benos University of Thessaly, Volos, Greece C. Day Karlsruhe Institute of Technology, FZK, Germany D. Dimopoulos University of Thessaly, Volos, Greece C. Dritselis University of Thessaly, Volos, Greece D. Fidaros Thessaly Technology Centre, Volos, Greece A. Grecos University of Thessaly, Volos, Greece D. Grigoriadis Univ. of Cyprus, Nicosia, Cyprus V. Hauer Karlsruhe Institute of Technology, FZK, Germany K. Hizanidis National Technical University of Athens, Greece A. Iatrides University of Thessaly, Volos, Greece S. Kakarantzas Univ. Libre de Bruxelles, Belgium J. Lihnaropoulos University of Thessaly, Volos, Greece POSTER PRESENTERS S. Misdanitis University of Thessaly, Volos, Greece S. Moustaizis Technical University of Crete, Chania, Greece S. Pantazis University of Thessaly, Volos, Greece N. Pelekasis University of Thessaly, Greece K. Perrakis Technical University of Crete, Chania, Greece I. Sarris University of Thessaly, Volos, Greece H. Tasso Max Planck Inst. of Plasma Physics, Garching, Germany G. Throumoulopoulos University of Ioannina, Greece D. Valougeorgis University of Thessaly, Volos, Greece S. Varoutis Karlsruhe Institute of Technology, FZK, Germany D. Vavougios University of Thessaly, Volos, Greece N. Vlachos University of Thessaly, Volos, Greece A. Xagoni National Technical University of Athens, Greece ADMINISTRATIVE COMMITTEE OF HELLENIC FUSION PROGRAMME I. Papazoglou (Chairman), NCSR Demokritos E. Stavrianoudaki, General Secretariat for R&T, V. Kamenopoulou, Greek Atomic Energy Committee G. Nikolaou, U. Thrace K. Hizanidis, Natl Tech. U. Athens SCIENTIFIC PROGRAMME COMMITTEE G. Throumoulopoulos (U. of Ioannina) L. Vlahos (U of Thessaloniki) N. Vlachos (U of Thessaly) LOCAL ORGANIZING COMMITTEE N. Vlachos (coord.) C. Dritselis (secr.) N. Pelekasis I. Sarris D. Valourgeorgis D. Vavougios Tech. Support: J. Lihnaropoulos (coord.), E. Benos, D. Dimopoulos, A. Iatridis, S. Misdanitis, S. Pantazis Registration desk: M. Angeli N. Sachinidou Z. Zoupi GROUP LEADERS OF HELLENIC FUSION PROGRAMME K. Hizanidis Elec. Eng. & Comp. Eng., NTUA G. Throumoulopoulos Physics, U. Ioannina P. Lalousis Inst. Laser, FORTH, Crete I. Tigelis Physics, U of Athens S. Moustaizis Tech U of Crete L. Vlahos Physics, Aristotle U of Thessaloniki I. Stamatelatos INTRP, NCSR Demokritos N. Vlachos Mechanical Engng, U. of Thessaly S. Kassinos Mech. Engng, U. of Cyprus Head of Hellenic Fusion Research Unit: K. Hizanidis (NTUA) kyriakos@central.ntua.gr Information: (I. Tigelis: itigelis@phys.uoa.gr) G. Throumoulopoulos gthroum@uoi.gr L. Vlahos vlahos@astro.auth.gr N. Vlachos vlachos@mie.uth.gr School Secretary: Dr Chris Dritselis Tel dritseli@mie.uth.gr The organizers of the Volos Fusion Schools gratefully acknowledge funding by the European Commission, the General Secretariat for R&T, and the University of Thessaly 20/20