A repetitive 800 kA linear transformer drivers stage for Z-pinch driven fusion-fission hybrid reactor

This paper presents the design and tests of a repetitive 800 kA fast linear transformer driver (LTD) stage aimed for the Z-pinch driven fusion-fission hybrid reactor (Z-FFR).The LTD stage consists of 34 parallel basic resistor R, inductor L, and capacitor C (RLC) circuits each made up of two 100 kV/40 nF capacitors, a multi-stage gas switch and Metglas magnetic cores. The stage can deliver about 800 kA current pulse with rise time of 100 ns into the matched liquid resistive load at a repetitive frequency 0.1 Hz. A novel method to trigger the stage via a continuous internal trigger bus composed by a single cable has been proposed and demonstrated. The experimental results show that the new trigger method is feasible and reliable. A 140 kV, 25 ns rising time trigger pulse, and a 5.2 kA, 30 μs width pre-magnetization current pulse which can operate at a repetition rate 0.1 Hz were used in this stage to insure the LTD stage generating a 80 kV/800 kA current pulse every 10 s. A multi-stage gas switch that has a lifetime in excess of 10,000 shots and a jitter less than 3 ns one sigma agrees well with the demand of Z-FFR. The electrical behavior of the stage can be predicted from a simple RLC circuit, which can simplify the design of various LTD-based accelerators.