Ion Doppler Spectroscopic Measurement with a Multi-channel PMT on Spheromak Plasmas

Abstract

An ion Doppler spectrometer (IDS) using a compact 16 channel photomultiplier tube (PMT) has been developed and used to measure ion temperature and toroidal rotation speed on SSPX gun-spheromaks. Doppler broadening of OV spectral line shows higher ion temperature (-500 eV) as compared to the electron temperature, which indicates anomalous ion heating due to MHD relaxation. It has been also found that the plasma rotates with a speed of 60 km/s in the direction of E×B.