Vibrational States of Hydrogen Molecules in One Third LHD Negative Ion Source

Abstract

EVWUDFW The effect of the cesium on hydrogen negative ions is discussed using the vacuum ultraviolet emissions (VUV) from vibrational states of hydrogen molecules. The VUV spectrum from 90 to 165 nm is related to the H -production from the dissociative attachment of electrons to hydrogen molecules. The VUV spectra in hydrogen plasmas are measured in the extraction region of a negative ion source for neutral beam injector. Under the pure hydrogen discharge, the cesium vapor is introduced into the ion source to enhance the hydrogen negative ion density. When the same arc power of ~99kW is applied in both with and without cesium admixture cases, the ratio of the observed VUV spectrum without to with cesium is not changed clearly. Therefore the production process of H -related to the wall/electrode surface would be enhanced rather than the volume production process..H\ZRUGV negative ions, vibrational states, VUV spectrum, ion source, hydrogen molecules