Development of an Ion Beam Probe System for Potential Measurement in the Low Aspect-Ratio Torus Experiment Device

Abstract

To investigate confinement and transport characteristics in the low aspect-ratio torus plasmas which are produced and maintained solely by electron Bernstein waves in the LATE device, we are developing an ion beam probe system for potential measurement. After some component tests, the injection and the detection beam lines are installed on LATE, and the ion beams are injected in vacuum with the toroidal field, where the beam positions and profiles are observed by matrix plates detectors. It is confirmed that the beam positions are controlled by the sweeper and the deflector voltages correctly. However, the beam spreads in the toroidal direction widely and focussing of the beam is necessary. The basic design of the energy analyzer is completed to detect a potential difference of ∼1 V.