System design and engineering for baking of the KTM vacuum vessel

Abstract

In tokamaks, residual gases and especially water vapors adsorbed in shell pores are removed by baking the vacuum vessel (VV) and in-vessel elements to a temperature not lower than 200 °С. The combined method for VV baking is proposed for the KTM tokamak, namely, baking by ohmic heaters to heat the outer shell of the vacuum vessel (the main method) and by eddy currents induced, mainly, in the inner shell by the central solenoid (CS) (additional induction method). To realize the proposed method the authors have developed the baking system consisting of active heaters arranged on the VV outer shell and an AC source supplying the central solenoid initiating eddy currents in the shell of the VV inner cylinder. The process of the KTM VV baking was numerically simulated by the numerical simulator developed by the authors. As a result, (a) the baking scenario has been defined, which satisfies the requirements both for the process duration and for the temperature non-uniformity; (b) the requirements have been formulated for the induction heating source and power supply source of the outer heaters.