Multi-pulse electron diode development for flash radiography

Presently the Self Magnetic Pinch (SMP) diode is successfully utilized for flash radiography with pulsed power drivers. However, it is not capable of more than one pulse. Multi-pulse single-axis radiography is most preferred since it provides images of time-evolving dynamic targets. In an SMP diode, because the anode cathode (A-K) gap is very small (~1-2 cm), the debris from the anode converter target arrives soon after the first pulse and completely destroy the cathode electron emitter, and thus the diode cannot produce a second pulse. We propose a feasibility study to scientifically evaluate the idea of decoupling the anode converter from the cathode electron emitter. This work will be based on two successful previous works we have accomplished: first, making a very small pencil-like beam in a magnetically immersed foilless diode (M.G. Mazarakis et al., Applied Physics Letters, 7, pp. 832 (1996)); and second, successfully demonstrating the two-pulse operation of a foilless diode with the RIIM accelerator (M. G. Mazarakis et al., Applied Physics 64 part I pp. 4815, (1988) Our approach will combine the above experimentally demonstrated successful work. The generated beam of 40-50 kA will be propagated in the same diode magnetic solenoid for a sufficient distance before striking the converter target. This way the diode could be multi-pulsed before the target debris reaches the cathode. Although the above describes the option of a foilless diode and a solenoidal transport system, a similar design could be made for a non-immersed low emittance 10 kA velvet emitter foilless diode.