Profiles Control and Stability in Thermonuclear Fusion: Some Issues for ITER
Event details
| Date | 20.06.2012 |
| Hour | 11:00 › 12:00 |
| Speaker | Prof. E. Witrant, University Joseph Fourier, Grenoble, France |
| Location |
PPH 275
|
| Category | Conferences - Seminars |
Controlled thermonuclear fusion is a topic of prime interest as a source of sustainable energy, which could possibly compete with classical fission reactors in terms of efficiency and as a key process to produce energy. In the forthcoming years, the main challenge for the fusion community will be to develop experimental scenarios for ITER (the largest fusion process ever built and with a first run planned for 2020). Amongst the key issues, the main control challenges are related to the plasma shape control, advanced equilibrium profiles for Tokamaks and the stabilization of magnetohydrodynamic (MHD) modes. Shape control has been studied extensively but many results still have to be discovered on the other two topics, where the nonhomogeneous transport of waves, energy and particles appear as fundamental.
After a general overview on fusion and the key issues from the control point of view, the proposed talk will detail some recent advances on current profiles control carried in Tore Supra (CEA Cadarache, South of France). Indeed, a particular interest is given to the current density and the way to produce plasma current. Due to the intrinsic limitation on magnetic flux availability in fusion processes to maintain a purely inductive current, the use of noninductive sources to generate most of the current is inevitable. Modelling and real-time control of radiofrequency antennas (current source distributed in the plasma) are of prime importance to optimize the confinement and to ensure the profiles robustness with respect to external perturbations.
Another advanced problem for control will also be considered: the stabilization of MHD modes. MHD phenomena have several impacts on plasma; one of them is to generate unstable modes, such as those studied in the Reversed Field Pinch EXTRAP-T2 (Alfvèn lab, KTH, Sweden). These modes are of capital importance in fusion reactors, as a lack of their stabilization leads to the loss of confinement. Their time constant is typically a few milliseconds, with a control cycle of 100 μs for the simplest feedback rules. The complexity of 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.
After a general overview on fusion and the key issues from the control point of view, the proposed talk will detail some recent advances on current profiles control carried in Tore Supra (CEA Cadarache, South of France). Indeed, a particular interest is given to the current density and the way to produce plasma current. Due to the intrinsic limitation on magnetic flux availability in fusion processes to maintain a purely inductive current, the use of noninductive sources to generate most of the current is inevitable. Modelling and real-time control of radiofrequency antennas (current source distributed in the plasma) are of prime importance to optimize the confinement and to ensure the profiles robustness with respect to external perturbations.
Another advanced problem for control will also be considered: the stabilization of MHD modes. MHD phenomena have several impacts on plasma; one of them is to generate unstable modes, such as those studied in the Reversed Field Pinch EXTRAP-T2 (Alfvèn lab, KTH, Sweden). These modes are of capital importance in fusion reactors, as a lack of their stabilization leads to the loss of confinement. Their time constant is typically a few milliseconds, with a control cycle of 100 μs for the simplest feedback rules. The complexity of 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.
Practical information
- Expert
- Free
Organizer
- CRPP
Contact
- Paolo Ricci