Dark current in high-gradient accelerator

A report is presented on the first measurements from a program to study high-gradient linear e/sup +//e/sup -/ accelerators, as part of a research and development program on linear colliders. The experimental setup is a realistic S-band, traveling-wave, disk-loaded warm accelerating structure, fed by long RF pulses. The dark current produced by field emission has been investigated. The peak current is about 0.2 mA/m and the steady current 40 mu A/m, for an accelerating field of 30 MV/m. The global field enhancement is beta =140. The level of dose rate is under 4 rad/h.<
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