Long-pulse modulator-driven cyclotron autoresonance maser and free-electron laser experiments at MIT

摘要

Abstract: High-power CARM and FEL research on a long-pulse (1 $mu@s) high-voltage (700 kV) modulator at the MIT Plasma Fusion Center is described. The experimental results on a Ka-band, long-pulse CARM oscillator experiment are presented. In this experiment, a SLAC 5045 klystron gun produced an electron beam at 250-320 kV and 10-20 A; a beam $alpha $EQV $rho$PRP@/$rho$PLL, variable from 0 to 1, was produced on this electron beam with a wiggler magnetic field near guide field resonance. CARM operation was observed for many parameter settings, and for frequencies ranging from 29 to 32 GHz. Output powers as high as 110 kW were achieved with an efficiency of up to 1.8%. Higher frequency radiation at 74.5 GHz was also obtained and is attributed to second harmonic CARM operation. Recent operation of an FEL experiment using a 580 kV, 0.27 $mu$Rho electron gun, built by Thomson Tubes Electroniques, and a permanent magnet helical wiggler with $lambda$- approximately ega$/ $EQ 3 cm and B$- approximately ega$/ $EQ 500 G is described. Results include measurement of small signal gain, gain-bandwidth, and oscillation at 30 GHz, with power levels of approximately 1 MW.!