Plasma Electrode Shape Suitable for Negative Hydrogen Ion Production

8 Sep 2020, 02:00
2h
Poster H– and D– sources for fusion, accelerators and other applications P2

Speaker

Keita Bito (Graduate School of Science and Engineering, Doshisha University)

Description

Introduction of cesium (Cs) into an ion sources enhances the production of negative hydrogen (H$^-$) ions while suppresses the co-extracted electron current by reducing the work function of the plasma grid surface [1-2]. However, cesium injection into an ion sources should require periodical maintenance and can add serious complexity in operation in a strong neutron /gamma radiation environment. Thus, the development of Cs-free H$^-$ / D$^-$ sources is desirable.

We have been investigating the amount of H$^-$ current and the amount of co-extracted electron current when C12A7 electride or molybdenum (Mo) were used for the Plasma electrode (PE) in a compact ECR ion source with an exchangeable PE. The C12A7 electride has a low work function, and it is expected to increase the amount of H$^-$ ion current and suppress the co-extracted electron current when used as the PE material [3]. In this study, we focus on the H$^-$ ion extraction and electron coextraction due to the shape of the PE of a H$^-$ ion source. Two materials: Mo and C12A7 electride are examined for a search of extraction structure suitable for a Cs-free ion source.

Primary author

Keita Bito (Graduate School of Science and Engineering, Doshisha University)

Co-authors

Mamiko Sasao (Office of R&D Promotion, Doshisha University) Prof. Motoi Wada (Graduate School of Science and Engineering, Doshisha University)

Presentation Materials