Modeling of the negative ion source and accelerator of the ITER Neutral Beam Injector

217 Pages·2017·4.35 MB·English

by  Gwenaël Fubiani

Modeling of the negative ion source and accelerator of
the ITER Neutral Beam Injector
G. Fubiani
To cite this version:
G. Fubiani. Modeling of the negative ion source and accelerator of the ITER Neutral Beam Injector.
Plasma Physics [physics.plasm-ph]. Université Toulouse III Paul Sabatier, 2016. ￿tel-01414273￿
HAL Id: tel-01414273
https://theses.hal.science/tel-01414273
Submitted on 22 Dec 2016
HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est
archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents
entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non,
lished or not. The documents may come from émanant des établissements d’enseignement et de
teaching and research institutions in France or recherche français ou étrangers, des laboratoires
abroad, or from public or private research centers. publics ou privés.
Modeling of the negative ion source and
accelerator of the ITER Neutral Beam Injector.
Gwena¨el Fubiani
GREPHE, CNRS/LAPLACE Laboratory
University of Toulouse (Paul Sabatier)
Accreditation to supervise research
Date of defence: 09/12/2016
Location: University of Toulouse (Paul Sabatier)
Members of the jury:
Anne Bourdon (LPP, CNRS) REFEREE
Khaled Hassouni (LSPM, U. of Paris XIII) REFEREE
Minh Quang Tran (EPFL, Switzerland) REFEREE
Jean-Pierre Boeuf (LAPLACE, CNRS)
Richard Fournier (LAPLACE, U. of Toulouse) PRESIDENT
Vanni Antoni (RFX, Italy)

To my two boys, my dear wife, my family and friends.

Who am I?
• Well, first of all, I am a proud father of two young boys! I guess this gives me
a “dad index” d = 2.
• I also have a h-index h = 13 corresponding to 850 citations (excluding self-
citations) on September 23rd 2016.
• I am first author of 9 articles in peer-reviewed journals and of 3 conference
proceedings.
• I co-authored 13 articles in peer-reviewed journals and 9 in conference proceed-
ings.
• 28 oral presentations at international conferences and workshops (1 invited talk
in a workshop, Yokohama, 2013). 15 posters.
• 2 invited seminars:
– Chamber of Commerce, Reggio Calabria, Italy, December 2011.
– AFRD, Lawrence Berkeley National Laboratory, Berkeley, CA, USA, June
2014.
• 1 technical report (LBNL 57514, http://escholarship.org/uc/item/1wf8w5fs).
• Co-author in 1 review paper (Reflet de la Physique, 2014)
• Member of the international committee of the NIBS conference (“Negative ions,
Beams and Sources”) since 2012
i
ii
• We have a grant from EUROfusion (for the moment until 2018). I am in charge
of the project.
• I designed the EAMCC model which simulates secondary particle production in
the accelerator of the ITER Neutral Beam Injector (NBI). It is used nowadays
by 4 laboratories in the fusion community (RFX - Italy, CEA - France, JAEA
- Japan and CCFE - UK).
• I co-directed the thesis of 2 PhD students:
– N. Kohen (defended in 2015). Nicolas worked on the modeling of the neu-
tral depletion inside fusion-type ion sources (chapter 5). He participated
with a former student to the coupling of the Direct-Simulation-Monte-
Carlo algorithm (DSMC) with a 2D implicit fluid model (developed by G.
Hagelaar)andanalyzedneutraldepletionversustheexternalparametersof
the negative ion source (power, background gas pressure and the incidence
of the magnetic filter field). Nicolas was co-author in one peer-reviewed
article.
– J. Claustre (defended in 2013). Jonathan developed a 2D and 3D PIC-
MCC model parallelized on a graphic card (Graphics Processing Unit,
GPU). He applied his model to the simulation of the ITER prototype
BATMAN ion source. Jonathan wrote 2 papers as first author (1 peer
reviewedjournaland1conferenceproceeding)andwasco-authorin1peer-
reviewed article. He is currently a post-doctoral researcher in Canada.
• Lastly, I had 3 students for an internship:
– One student from an engineer school (Polytech Orleans) for a duration of 3
month (2014). She learned how to model differential equations numerically
using the finite difference technique. At the end of her internship, she
studied a 2D multigrid solver applied to the Poisson equation.
– I had two students in Bachelor (University of Toulouse III, Paul Sabatier)
for a duration of 2 month (2016). I taught them the basic plasma physics
of a negative ion source.
iii
• I will be in charge of a PhD student next fall. He will work on the CYBELE
project in collaboration with IRFM (CEA, France), EPFL (Switzerland) and
LPSC (Grenoble, France).
• IwashiredbyCNRSin2007(butstartedworkinJanuary2008). Iamcurrently
in the GREPHE group at the LAPLACE laboratory (University of Toulouse,
Paul Sabatier, Toulouse, France).
• I was a post-doctoral researcher at IRFM, CEA, Cadarache for 2 years (2006-
2007).
• I did my PhD thesis at the LOASIS group, Lawrence Berkeley National Labo-
ratory, Berkeley, CA, USA (2000-2005). I worked on laser-plasma interactions
(modeling)
• I studied theoretical physics at the University of Paris XI, Orsay (Bachelor and
Master).
– My Bachelor internship was at the Stanford Linear Accelerator Center
(SLAC), Stanford University, CA, USA (4 month, 1998). I developed a
model to analyze the background noise in the PEP-II accelerator. I was
co-author in 1 conference proceedings.
– During my Master, I had a 4 month internship at Thales Electron Device
(TED), Velizy, France (1999). I worked on the design of a Gyrotron.

Table of Contents
1 Introduction 1
2 Numerical model 13
2.1 Particle-in-Cell model of a negative ion source . . . . . . . . . . . . . 14
2.1.1 Parallelization . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.1.2 Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.1.3 2.5D PIC-MCC approximation . . . . . . . . . . . . . . . . . 18
2.1.4 External RF power absorption and Maxwellian heating in the
discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.2 Implementationofcollisionsinaparticlemodel-MCandDSMCmethods 22
2.3 Elastic and inelastic collision processes . . . . . . . . . . . . . . . . . 25
2.3.1 Physical chemistry of charged particles . . . . . . . . . . . . . 26
2.3.2 Physical chemistry of neutrals . . . . . . . . . . . . . . . . . . 29
2.4 Negative ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.5 Simulation domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3 The Hall effect in plasmas 35
3.1 General features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2 Simplified geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4 Comparisons between 2D and 3D PIC simulations 43
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.2 Simulation characteristics . . . . . . . . . . . . . . . . . . . . . . . . 44
4.2.1 Plasma dynamics in the plane perpendicular to the magnetic
field lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.2.2 Plasma dynamics in the plane parallel to the filter field lines . 47
v