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SUMMARY:Profiles Control and Stability in Thermonuclear Fusion: Some Issue
 s for ITER
DTSTART:20120620T110000
DTEND:20120620T120000
DTSTAMP:20260414T032134Z
UID:de87786e48150ce74955793c1051419fcf4101029b796fa9b2a57d53
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. E. Witrant\, University Joseph Fourier\, Grenoble\, Fra
 nce\nControlled thermonuclear fusion is a topic of prime interest as a sou
 rce of sustainable energy\, which could possibly compete with classical f
 ission reactors in terms of efficiency and as a key process to produce en
 ergy. In the forthcoming years\, the main challenge for the fusion commun
 ity will be to develop experimental scenarios for ITER (the largest fusion
  process ever built and with a first run planned for 2020). Amongst the k
 ey issues\, the main control challenges are related to the plasma shape c
 ontrol\, advanced equilibrium profiles for Tokamaks and the stabilization
  of magnetohydrodynamic (MHD) modes. Shape control has been studied exten
 sively but many results still have to be discovered on the other two topi
 cs\, where the nonhomogeneous transport of waves\, energy and particles a
 ppear as fundamental.\nAfter a general overview on fusion and the key issu
 es from the control point of view\, the proposed talk will detail some re
 cent advances on current profiles control carried in Tore Supra (CEA Cada
 rache\, South of France). Indeed\, a particular interest is given to the c
 urrent density and the way to produce plasma current. Due to the intrinsi
 c limitation on magnetic flux availability in fusion processes to maintai
 n a purely inductive current\, the use of noninductive sources to generat
 e most of the current is inevitable. Modelling and real-time control of r
 adiofrequency antennas (current source distributed in the plasma) are of p
 rime importance to optimize the confinement and to ensure the profiles ro
 bustness with respect to external perturbations.\nAnother advanced proble
 m for control will also be considered: the stabilization of MHD modes. MH
 D phenomena have several impacts on plasma\; one of them is to generate u
 nstable modes\, such as those studied in the Reversed Field Pinch EXTRAP-T
 2 (Alfvèn lab\, KTH\, Sweden). These modes are of capital importance in 
 fusion reactors\, as a lack of their stabilization leads to the loss of c
 onfinement. Their time constant is typically a few milliseconds\, with a 
 control cycle of 100 μs for the simplest feedback rules. The complexity o
 f the dynamics and the real-time constraints motivate new approaches for 
 modelling and control\, with an emphasis on time-delays\, as discussed in
  this talk.\n
LOCATION:PPH 275
STATUS:CONFIRMED
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