Electron Bernstein wave emission diagnostic assisted by reflectometry on TST-2 spherical tokamak.

A new electron Bemstein wave emission diagnostic consisting of a heterodyne radiometer and a reflectometer was installed on TST-2. The instrument has a frequency range from 5 to 12 GHz which covers partially the fundamental and fully covers the second and third harmonic emissions. X-mode emission perpendicular to the flux surface, generated by B-X-FX mode-conversion scenario, is measured. The mode-conversion efficiency is calculated using a one-dimensional full-wave code with the density profile obtained simultaneously from the reflectometer, and the electron temperature (T[sub e]) is estimated. The levels corresponding to the 100-150 eV range are measured from the plasma core region, and the mode-conversion efficiency is calculated to be 0.5-0.8, leading to T[sub e] of approximately 200 eV. In addition, it is found that the reflectivity measured by the reflectometer is consistent with the calculated mode-conversion efficiency. This property can be used for a direct measurement of the mode-conversion efficiency. [ABSTRACT FROM AUTHOR]