Radially Localized Measurements of Superthermal Electrons Using Oblique Electron Cyclotron Emission
Authors: S. Preische, P. C. Efthimion, S. M. Kaye
It is shown that radial localization of optically thin Electron Cyclotron Emission from superthermal electrons can be imposed by observation of emission upshifted fromthe thermal cyclotron resonance in the horizontal midplane of a tokamak. Anew and unique diagnostic has been proposed and operated to make radially localized measurements of superthermal electrons during Lower Hybrid Current Drive on the PBX-M tokamak. The superthermal electron density profile as well as moments of the electron energy distribution as a function of radius are measured during Lower Hybrid Current Drive. The time evolution of these measurements after the Lower Hybrid power is turned off are given and the observed behavior reflects the collisional isotropization of the energy distribution and radial diffusion of the spatial profile.