Directory Intranet
Chargement
  

TORID - Tokamak Control of plasma Radial profiles in Infinite Dimensional setting

Project Coordinator : CEA IRFM
Project Manager at GIPSA-lab : Emmanuel WITRANT

Project realized thanks to the support of : ANR Blanc

Start date : 2012/01/03

Duration : 48 mounths


 

Fossil fuels (oil, gas, coal) account for approximately 85% of the worldwide sources of primary energy today. But they should run out with in some tens of years and they are responsible for a climate change via the contribution in the greenhouse effect of the CO2 generated by their combustion. Magnetic fusion is one of the options being studied in order to eventually provide an answer to these issues. Its main assets are to be a potential inexhaustible and safe source of energy because the reserves in nuclear fuel are plenty (Deuterium can be extracted from sea water, and Lithium, that has to be used to breed Tritium, can be found in continental crust) and because there is no risk of runaway reaction nor long lasting radioactive waste. Several conditions have to be met to produce fusion reactions : the fuels have to be heated up to very high temperature (around 100 millions degrees) in order to overcome the electrostatic potential barrier between positively charged nucleus. To reach such a temperature, the ionized gas or plasma must be confined, for example by magnetic confinement in a so-called tokamak1 [Wes97] facility, which seems to be the most promising way. The key world project in the domain, ITER (www.iter.org) , is led by seven Partners (Europe, United States of America, Japan, China, India, South Korea, Russia) accounting for one half of the world population. The main objective of the ITER project is to demonstrate the scientific feasibility of magnetic fusion. The ITER tokamak facility is currently under construction in Cadarache in France, with first experiment scheduled for 2020.
Tokamak control issues are becoming more and more important for the success of magnetic fusion research and will be crucial for ITER ([IEEECSM05], [IEEECSM06]). Feedback control of the main plasma macroscopic parameters, such as plasma position and shape, total current or density is now quite well mastered in the different worldwide tokamaks. But the control of internal plasma radial profiles is still in its infancy, whereas it now appears to be crucial in order both to ensure safe tokamak operation and to sustain high performance plasma regimes. More precisely, it is known that the so-called safety factor profile is a key parameter for the global stability of plasma discharges and it has also been observed that some specific safety factor profiles may generate some enhanced confinement of the plasma energy, which may reduce the size and cost of future fusion reactors. The aim of the Project is to bring together teams of researchers in feedback control, applied mathematics and plasma physics in order to make a significant step forward on theses key issues through the design and implementation of advanced control schemes on the Tore Supra tokamak presently under operation at Cadarache, France, in view of plasma profiles and associated fusion burn control in ITER.

The TORID Project (Tokamak cOntrol of plasma Radial profiles in Infinite Dimensional setting) aims at bringing together teams of researchers in feedback control, applied mathematics and plasma physics in order to make a significant step forward on a key issue in magnetic fusion control research : the control of 1D distributed plasma profiles in the so called tokamak facilities. Feedback control of the main macroscopic plasma parameters is now quite well mastered in the different worldwide tokamaks, but the control of plasma radial profiles, in particular the so-called safety factor profile, is still in its infancy, whereas it now appears to be crucial in order both to ensure safe operation and to sustain high performance regimes. This issue will have a direct impact on the success of the key world project in the domain, ITER, which is presently under construction in Cadarache, in the South of France, but also to reduce the size and cost of future fusion reactors.
The specific target of this Project with respect to the state of the art is : (a) to develop control approaches in infinite dimensional setting in view of potential benefit in terms of better handling of non linear couplings and physics model uncertainties as compared to previously developed finite dimensional approaches; (b) to implement the resulting advanced control algorithms on the French Tore Supra tokamak which, due to its capability to run long lasting plasma discharges, offers a unique opportunity to develop and test plasma safety factor profile control schemes on relevant time scales.

The scientific and technical programme will follow a staged approach with four tasks of increasing complexity :
(1) Task 1 will aim at testing on real experiments some preliminary control algorithms, based on a reduced reference model featuring one single Partial Differential Equation (resistive diffusion of the magnetic flux) and a reduced set of control inputs, that were recently designed by the Partners under the framework of pre-existing collaborations;
(2) Task 2 will aim at extending the approach to a more comprehensive / consistent model, including the couplings to a second Partial Differential Equation (heat transport equation), taken in its steady state limit to begin with, as justified by the ordering or corresponding time scales;
(3) Task 3 will aim at a complete handling of the two coupled PDEs without the previous assumption;
(4) Task 4 will finally aim at studying the possibility to apply the previously developed methods to fusion burn control that will also bring into play the coupling between PDEs (heat and particle transport equations). Each of these 4 tasks will be supported by activities in 4 fields of expertise as brought by the Partners, namely control oriented modelling, control law design, Partial Differential Equation parameters estimation and integration of the previous activities either on numerical simulations or on real experiment on the Tore Supra tokamak.


GIPSA-lab, 11 rue des Mathématiques, Grenoble Campus BP46, F-38402 SAINT MARTIN D'HERES CEDEX - 33 (0)4 76 82 71 31