Abstract
Isotope effect on H^–^/D^–^ volume production is studied by measuring both VUV emission and negative ion density in the source. In a double plasma type source, under some discharge conditions, extracted D^–^ currents are nearly the same as H^–^ currents, although VUV emission intensity (corresponding to production of vibrationally excited molecules) in D~2~ plasmas is slightly lower than that in H~2~ plasmas. Considering the factor √2 due to mass difference, D^–^ ion density in the extraction region of the source is higher than H^–^ ion density. In another experiment with a rectangular arc chamber, axial distributions of H^–^/D^–^ ion densities in the source are measured directly using a laser photodetachment method. Relationship between H^–^/D^–^ production and plasma parameter control with using a magnetic filter (MF) is discussed. Furthermore, relative intensities of extracted negative ion currents are discussed compared with the negative ion densities in the source. Production and control of D~2~ plasmas are well realized with the MF including good combination between the filament position and field intensity of the MF. Extracted H^–^ and D^–^ currents depend directly on negative ion densities in the source. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)