Sensitive Detection of Probing Electron Transport and Magnetic Field Structure in Toroidal Plasma Configuration

Abstract

Novel diagnostic instrumentation for imaging test electron transport in a small tokamak has been developed by using the following techniques: electron beam probing with scanned fluorescent rod and boxcar image integration with repetitive tokamak discharges. In order to detect the electron beam not in vacuum but in a low-temperature plasma, the fluorescence from a phosphor with long fluorescent decay time is discriminated from plasma radiation by taking fluorescent images after each discharge shot. Disturbed magnetic field in a simple torus has been sensitively detected by the distortion of electron orbits. A modification of electron beam transport in a low-temperature tokamak plasma has been detected with high spatial resolution for a slight change in the external magnetic field.