Plasma and Fusion Research

Volume 13, 1205110 (2018)

Rapid Communications


Demonstration of Beam Optics Optimization Using Plasma Grid Bias in a Negative Ion Source
Masashi KISAKI1), Katsunori IKEDA1), Haruhisa NAKANO1,2), Katsuyoshi TSUMORI1,2), Yutaka FUJIWARA1), Yasuaki HABA3), Shuji KAMIO1), Kenichi NAGAOKA1,3) and Masaki OSAKABE1,2)
1)
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
2)
SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292, Japan
3)
Graduate School of Science, Nagoya University, Nagoya 464-8601, Japan
(Received 18 June 2018 / Accepted 7 August 2018 / Published 10 September 2018)

Abstract

Plasma grid bias has been utilized for reducing an electron density in the vicinity of a plasma grid in negative ion sources for fusion, resulting in achievement of low co-extracted electron current. In this study, the effectiveness and feasibility of the plasma grid bias on beam optics optimization are demonstrated. It is shown that the beam optics strongly depends on the bias voltage and is successfully optimized at different bias voltages depending on the discharge power. Responses of the beam properties such as the perveance and the current ratio to the plasma grid bias are also shown for both hydrogen and deuterium beams.


Keywords

hydrogen negative ion source, beam optics, meniscus, perveance, plasma grid bias

DOI: 10.1585/pfr.13.1205110


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