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Published on: May 25, 2021
D(-)/H(-) negative ion production versus plasma parameters in a volume negative ion source
Shigefumi Mori1, Osamu Fukumasa
1Graduate School of Science and Engineering, Yamaguchi University, Ube, Japan.
Investigating negative ion source performance, this study found deuterium (D(-)) production differs from hydrogen (H(-)) despite similar plasma conditions. Optimal magnetic filter fields and pressures for D(-) are slightly higher than for H(-).
Area of Science:
- Plasma Physics
- Atomic and Molecular Physics
- Ion Source Technology
Background:
- Pure volume production of negative ions is crucial for applications like neutral beam injection.
- External magnetic filters (MF) are used to control plasma parameters in negative ion sources.
- Understanding differences in D(-) and H(-) production is key for optimizing ion source performance.
Purpose of the Study:
- To investigate the pure volume production of D(-) negative ions in a rectangular negative ion source with an external magnetic filter.
- To analyze the influence of magnetic filter field intensity (B(MF)) on plasma parameters (electron density n(e), electron temperature T(e)) and D(-) production.
- To compare D(-) production characteristics with H(-) production under varied plasma conditions.
Main Methods:
- Utilized a rectangular negative ion source with an external magnetic filter.
- Varied the magnetic field intensity of the MF (B(MF)) to alter plasma parameters (n(e), T(e)) in the downstream region.
- Compared D(-) and H(-) production efficiencies under identical discharge conditions.
Main Results:
- D(2) plasma parameters (n(e), T(e)) were slightly higher than H(2) plasma parameters.
- H(-) production varied significantly with B(MF), correlating with changes in downstream n(e) and T(e).
- D(-) production showed less variation with B(MF) compared to H(-), indicating factors beyond n(e) and T(e) influence its production.
Conclusions:
- The production mechanism of D(-) ions differs from H(-) ions, not solely explained by variations in electron density and temperature.
- Optimal magnetic filter field intensity and gas pressure for D(-) production are slightly higher than those for H(-) production.
- Further research is needed to fully elucidate the distinct production pathways of D(-) and H(-) in magnetic filter-equipped ion sources.
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