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Contribution Oral

H– and D– sources for fusion, accelerators and other applications

Study of H- extraction from a single-hole plasma electrode of C12A7 electride


  • Dr. Mamiko SASAO

Primary authors



Recently, it has been reported that a high production rate of negative hydrogen ion (H-) was observed from a nano-porous C12A7 electride surface immersed in hydrogen/deuterium low-pressure plasmas [1].  The H- ion energy spectrum seemed to indicate that the dominant process leading to H- ion formation was through kinetic desorption induced by low energy ions. Fundamental understanding of the production mechanism is not fully clarified yet.  Negative ions can be produced through (1) charge exchange(electron pick-up) reflection process and (2) desorption process by sputtering. When the plasma electrode was fabricated with the C12A7 electride, it is not clear whether the high production rate through desorption process is effective in a real ion source, or not. In addition, it is not clear whether the high production rate of H- ions on the C12A7 electride is owing to the characteristic feature of the low-work function, or the cage structure that contains H- ions in it.   Present work deals with negative ion production on a C12A7 electride surface for a cesium free ion source, and H- extraction from a single-hole plasma electrode. In order to investigate these problems, a small device with an ECR plasma source and C12A7 electride plasma grid has been constructed. The work function of the plasma gird surface can be monitored by injecting lasers of various wavelength, and extracted H- current will be measured.

[1] M. Sasao, et al, Applied Physics Express 11, 066201 (2018)