Diagnosing the Electron Distribution Function with Oblique Electron Cyclotron Emission on Ftu

This paper addresses the problem of diagnosing the electron distribution function by measuring Electron Cyclotron Emission (ECE) at different angles with respect to the magnetic field. This diagnostic set-up, that is often referred to as oblique ECE, provides a unique method for measuring the electron distribution function with good energy and space resolution at once. First oblique ECE measurements have been performed on FTU during on-axis Electron Cyclotron Resonance Heating (ECRH) applied on the current ramp-up phase of the discharge. The experimental results appear to be consistent with theoretical Fokker-Planck calculations, showing the existence of a deformation of the bulk of the electron distribution function.