A collective Thomson scattering diagnostic is being implemented at JET to diagnose the velocity distribution and density of alpha particles and energetic ions. This diagnostic consists of a number of major subsystems including: a high-power 140-GHz gyrotron, a 32-channel 12-GHz bandwidth heterodyne receiver, efficient corrugated waveguide systems, variable polarizers, and in vacuum beam steering mirrors. Proper calibration of these subsystems for signal level losses, positioning, and polarization is imperative for the successful operation of the diagnostic and to facilitate the interpretation of the scattered data. A low-power Gunn oscillator was used to verify the polarization rotation induced by the seven miter bends in the receiver transmission line. The full bandwidth receiver front end losses, including the sapphire tokamak vacuum window, were initially calibrated by using the hot tokamak vessel wall as a blackbody source at approximately 310° C. Background ECE measurements will be presented.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)
Machuzak, J. S., Woskov, P. P., Bindslev, H., Comiskey, M., Fessey, J., Hoekzema, J. A., ... Orsitto, F. (1992). Receiver calibration of the JET fast ion and alpha particle diagnostic. Review of Scientific Instruments, 63(10), 4648 - 4650. https://doi.org/10.1063/1.1143648