Volume production of negative ions in the reflex type ion source
The production of negative hydrogen ions is investigated in the reflex-type negative ion source. The extracted negative hydrogen currents of 9.7 mA (100 mA/cm/sup 2/) for H/sup -/ and of 4.1 mA (42 mA/cm/sup 2/) for D/sup -/ are obtained continuously. The impurity is less then 1%. An isotope effect of negative ion production is observed. When anomalous diffusion in the positive column was found by Lehnert and Hoh (1960), it was pointed out that the large particle loss produced by anomalous diffusion is compensated by the large particle production inside the plasma, i.e., the plasma tries to maintain itself. The self-sustaining property of the plasma is applied to the reflex-type negative ion source. Anomalous diffusion was artificially encouraged by changing the radial electric field inside the reflex discharge. The apparent encouragement of negative ion diffusion by the increase of density fluctuation amplitude is observed. Twice as much negative ion current was obtained with the artificial encouragement as without. It is found from the quasilinear theory that the inwardly directed radial electric field destabilizes the plasma in the reflex-type ion source. The nonlinear theory based on Yoshikawa method (1962) is extended, and the anomalous diffusion coefficient in a weakly ionized plasma is obtained. The electrostatic sheath trap, which increases the confinement of negative ions in the reflex-type ion source, is also discussed.
- Research Organization:
- California Univ., Berkeley (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5805886
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Volume production of negative ions in the reflex-type ion source
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