Proto II Triaxial Electron Beam Diode Research

摘要

The Proto II accelerator has been modified to provide electron beam diode loads for bremsstrahlung radiation production. Stable, reproducible operation has been established over a voltage range of 0.5 to 1.5 MV with diode power up to 5 TW. The electron beam diode consists of two nested triaxial diodes which operate independently due to transit time isolation of the power flow. Both the current balance and prepulse levels have been found to be critical to the operation of the diodes. Water switching spreads between the 8 modules of up to 15 ns do not impair diode performance. Ion currents due to bipolar flow have been measured and are relatively low, consistent with triaxial diode models. Radiation output has been measured and compared with radiation transport code calculations. At the highest operating voltages, peak dose rates of >1.2 x 10 sup 12 rad(Si)/s over >250 cm sup 2 (2:1 uniformity) are routinely obtained in radiation pulses with a full-width, half-maximum (FWHM) of 22 ns. (ERA citation 12:046086)