Evaluation of electromagnetic force in tokamak first wall based on magnetic field measurement and inverse analysis

Abstract

Electromagnetic force due to induced eddy current during plasma disruptions is one of the key design-driving issues for the first wall (FW) in the Tokamak device. In this paper, a method to evaluate the electromagnetic force in the FW is proposed based on inversion of the measured magnetic field. An inversion scheme for reconstruction of eddy current from measured magnetic field is developed based on a newly proposed algorithm that can eliminate the effect of plasma current. To solve this inverse problem, the conjugate gradient (CG) algorithm is adopted in addition with an efficient parameterization strategy of eddy current distribution. To demonstrate the efficiency of the method, a simplified FW plate and plasma current model is considered with the magnetic field simulated with a numerical code of the reduced magnetic vector potential (Ar) formulation. The numerical results show that proper eddy current and electromagnetic force distribution can be predicted even for case of unknown plasma current, which reveals that the proposed method has good potential to be applied to the electromagnetic force evaluation of practical Tokamak problem.

Keywords

Electromagnetic force eddy current reconstruction first wall inverse analysis

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