Pressure optimization for H{sup -} ion production in an electron cyclotron resonance-driven and a filamented source
- LPTP, Ecole Polytechnique, UMR 7648 du CNRS, 91128 Palaiseau (France)
The negative ion density as a function of the hydrogen pressure (1-8 mTorr) in the electron cyclotron resonance-driven version of the magnetic multipole volume source 'Camembert III' is measured by means of the photodetachment technique. An optimum value is observed between 4 and 5 mTorr, yielding a H{sup -} ion density of about 1.5x10{sup 9} cm{sup -3} in the center of the source. The electron density monotonously increases in the range {approx}(0.5-2.5)x10{sup 10} cm{sup -3} and the electron temperature decreases ({approx}1.25-0.5 eV). The optimum pressure for H{sup -} production is equally reported for a conventional filamented multipole source, in which the influence of rovibrationally excited hydrogen molecules in the electronic ground state on the formation of H{sup -} is analyzed. The physical mechanism which determines the existence of this ion density maximum is discussed.
- OSTI ID:
- 20779017
- Journal Information:
- Review of Scientific Instruments, Vol. 77, Issue 3; Conference: 11. international conference on ion sources, Caen (France), 12-16 Sep 2005; Other Information: DOI: 10.1063/1.2172343; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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