Existence and estimate of the location of the free-boundary for a non local inverse elliptic-parabolic problem arising in nuclear fusion

Pages: 1176 - 1185, Issue Special, September 2011

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J. F. Padial - Dpto. Matemática Aplicada, Fac. de Matemáticas, U. Politécnica de Madrid, 28040 Madrid, Spain (email)

Abstract: We consider an inverse 2D free-boundary elliptic-parabolic problem, modeling the transient regime of a magnetically con ned plasma in a non ideal Stellarator device. The inverse nature of the problem comes from the fact that the associated Grad-Shafranov equation involves some unknown nonlinear terms which must be determined by the current-carrying Stellarator condition. One of the main diculties for the mathematical approach is due to the fact that these nonlinear terms are neither a monotone function and are nor a Lipschitz function either. Nevertheless, we can introduce an auxiliary problem for which the solution of our original problem is a supersolution. On the other hand, we can to obtain a subsolution for this new problem. Finally, by applying the comparison principle for quasi-linear problems, we obtain some appropriate estimates on the location and size of the plasma region.

Keywords:  Inverse nonlinear elliptic-parabolic problem, free boundary problem, relative rearrangement, location of free boundary, Current-carrying Stellarators
Mathematics Subject Classification:  Primary: 35J85; Secondary: 35R30

Received: August 2010;      Revised: July 2011;      Published: October 2011.