Basic processes of negative hydrogen ion production and destruction in sources and beams (invited)
- Laboratoire de Physique des Milieux Ionises, Laboratoire du C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)
This article contains the discussion of new discoveries and ideas relevant to volume H{sup {minus}} ion sources and beams. Recent research in laser irradiated H{sub 2} by Pinnaduwage and Christophorou has shown that the rates of dissociative attachment are strongly dependent on electronic excitation involving superexcited states and possibly Rydberg states. The observation of anomalous attenuation of a 15 keV H{sup {minus}} beam in a hydrogen gas target led us to consider the possibility of secondary H{sup {minus}} stripping processes, related to low-energy interactions between primary H{sup {minus}} ions and the secondary H{sup +}, H{sup 0}, and electron beams produced by primary stripping. The results of the investigation by electrostatic probes and by photodetachment of the properties of a hydrogen/deuterium multicusp ion source plasma when seeded with cesium vapor are reported. We found that the negative ion/electron density ratio is enhanced by cesium seeding, particularly at low pressure (a factor of 4 at 1 mTorr), while both the electron temperature and the electron density are reduced. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 434564
- Report Number(s):
- CONF-9509125-; ISSN 0034-6748; TRN: 97:003669
- Journal Information:
- Review of Scientific Instruments, Vol. 67, Issue 3; Conference: 6. international conference on ion sources, Whistler (Canada), 10-16 Sep 1995; Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
The role of high Rydberg states in the generation of negative ions in negative-ion discharges
Investigation by photodetachment and probes of H{sup {minus}}/D{sup {minus}} ion sources with cesium seeding