Production of an intense, well-collimated submillimeter wave beam and its application to plasma scattering measurements

摘要

Intense submillimeter wavelength radiation (f = 354 GHz, P = 110 W) from Gyrotron FU II is converted into a well-collimated, linearly-polarized beam by a quasi-optical transmission line consisting of a quasi-optical antenna and several mirrors. The observed focusing of the beam agrees with calculations based on the Huygens equation. We have used this intense beam to study low frequency density fluctuations by plasma scattering in Compact Helical System (CHS) plasmas at the National Institute for Fusion Science.