Microwave transmission measurements in Tore Supra
Microwave transmission in the electron-cyclotron frequency range is a promising diagnostic method. A transmission diagnostic system working in the frequency range 77-97 GHz, below the thermal electron gyrofrequency, has recently been implemented in the Tore Supra tokamak. It makes use of an ordinary mode launched along a vertical diameter, so propagating along a nearly constant magnetic field. A modulation of the incident power allows an increase of the signal to noise ratio. The physical principles of the diagnostic, as well as the Tore Supra system, are discussed. Experimental results obtained in both ohmic and lower-hybrid driven discharges are presented. In the first case, in the absence of absorption due to fast electrons, both density sawteeth and m = 1 modes are clearly observed. In the second case, the measurements made with a good temporal resolution display strong absorption by relativistic electrons sustained by the lower-hybrid waves, and a fast frequency scanning allows, in principle, a determination of the parallel electron velocity distribution. Good agreement is found with the value of the driven current.
Bibliographic Reference: Paper presented: Diagnostics for Contemporary Fusion Experiments, Varenna (IT), Aug. 27 - Sept. 6, 1991
Availability: Available from (1) as Paper EN 36320 ORA
Record Number: 199111106 / Last updated on: 1994-12-02
Original language: en
Available languages: en