Resistive loss compensation in the power supply system of the toroidal field winding in the TUMAN-3M tokamak

Abstract

In the tokamak, in which the winding generating the toroidal field with induction B _t is powered from an inductive energy storage, resistive losses are the main factor that causes B _t to decrease during a discharge. Upgrading of the power supply circuit of the toroidal magnetic field winding (TFW) in the TUMAN-3M tokamak is aimed, primarily, at increasing B _t in the injection heating phase and, second, at maintaining B _t quasi-stationarity during the whole tokamak discharge. To do this, an additional two-section capacitive storage commuted by two thyristor switches has been introduced into the available circuit. Either section of the storage is characterized by a charging voltage of 0.25 kV, a capacitance of 4.32 F, and an energy capacity of 135 kJ. The maximum discharge current of the section is 40 kA. The upgraded circuit compensates for the resistive loss in the TFW and ensures thereby a 50% increase in the magnetic field during injection heating relative to the old circuit: B _t = 1.0 T instead of 0.68 T. In this case, the circuit maintains a TFW current of 110 kA with an accuracy of 10% for ∼60 ms.