Measurement of the Parallel velocity distribution function of the electron beam in a quasi-optical gyrotron by electron cyclotron emission
The parallel velocity distribution function of the weakly relativistic electron beam of a quasioptical gyrotron (QOG) has been determined by measuring the Doppler shifted Electron Cyclotron Emission (ECE) at an angle theta = 15 with respect to the external magnetic direct current field. Due to the Doppler shift, the frequency of the spontaneous cyclotron emission at the fundamental (nu(0) = 100 GHz) is upshifted to 140 GHz. A broadening of the spectrum up to 10 GHz (Full Width at Half Maximum FWHM) was measured. The measured mean frequency agrees well with the theoretical predictions, but the observed line width, and hence the parallel velocity distribution function, is between 2 and 3 times larger than expected. Considerations on ECE measurements of the electron beam energy spread, performed at larger angles theta, are also discussed.
Bibliographic Reference: Article: Physics of Plasmas (1996)
Record Number: 199610394 / Last updated on: 1996-04-15
Original language: en
Available languages: en