Cyclotron radiation as a diagnostic tool for tokamak plasmas

Abstract

A code has been developed which calculates the cyclotron radiation spectrum emitted by a slab model tokamak plasma in a direction outward along a major radius. The calculation assumes both a thermal and a suprathermal electron component for the plasma, and includes the effects of self-absorption of the radiation by the thermal plasma. Various methods are described by which the cyclotron radiation spectrum can be unfolded to obtain parameters of the electron population. A procedure is described by which the electron temperature profile can be obtained from spectral measurements of the cyclotron emission at optically thin frequencies. No absolute calibration of the detection equipment is needed for this method. The code can be used to find parameters of the suprathermal distribution function from its synchrotron emission spectrum, and for the special case of suprathermal electrons at a constant major radius, analytical results are obtained. Finally, the code has been used to calculate cyclotron spectra for various tokamaks: CLEO, TFR, ATC, PLT, and Alcator.