Plasma current control system in JIPP T-II

The control of plasma current has been adopted in JIPP T-II tokamak/stellarator. The power supply for the control is a combined system of transistor and thyristor sections which are connected in series. A role of the transistor section is quick and fine control. This power supply is coupled to the primary circuit of current transformer with a stack of 24 semiconductor diodes. This stack also plays a role of crowbarring ohmic heating current. We found experimentally that the plasma current can be kept constant within an error less than few percent. The one-turn loop voltage, ion temperature and electron temperature are found to be almost constant during the control. (author)