弱い相対論的電子ビームを用いた大口径W-band表面波発振器による大強度マイクロ波の発振特性

抄録

We studied an oversized W-band (75 - 110 GHz) surface wave oscillator driven by a weakly relativistic electron beam. Surface wave is formed on slow wave structure (SWS) with rectangular corrugations and has an upper-cutoff frequency of about 100 GHz. To excite the surface wave, an annular electron beam is generated by a disc type cold cathode with beam energy between about 10 and 80 keV. The oscillator is driven in the backward wave oscillator (BWO) region for beam energy less than 30 keV and in the traveling wave tube (TWT) region for beam energy more than 30 keV. In the BWO region, microwaves are generated due to Cherenkov interaction between electron beam and surface wave in the W-band. In the TWT region, two types of microwaves are generated. One is due to the W-band surface wave as in the case of the BWO region. The other is due to higher order modes above 140 GHz.