The power supply and control system for the MM-2U neutral beam injector

A single injector with one ion source has been constructed, which is provided for researching the stability effect of the sloshing ion distribution in the magnetic mirror experiment facility (MM-2U) by oblique injection of neutral beam. The neutral beam injector (NBI) can deliver 80 kW of neutral beam power at energy of 25 keV with 50 ms for MM-2U. In the present paper, a testing power supply for the neutral beam injector with injecting power up to 200 kW is described. A thyristor switch modulator applied to an arc power supply, it is capable of delivering 10 to 1000 A DC pulses at 20 to 100 V and pulse length up to 2 s with a duty cycle of 1/100. Both switching-on and switching off times of the circuit are less than O.5 ms. A high power vacuum tube TM-703F is used as the switch/regulator of the accel power supply, specifications of the circuit are as follows: output pulse voltage 50 kV, pulse current 30 A, pulse width 50 ms. Both the rise and fall times are less than 25 /spl mu/s, fluctuation of the pulse flat top less than 1%. A programmable controller by a DBJ-Z80 computer is applied to control the sequence of the power supply. The power supply and control system have been operated for 5 years successfully.