Development of a large-bore plasma window with an indirectly heated hollow cathode

Yamasaki K.

Sumino M.

Sunada Y.

Yanagi O.

Okuda K.

Kono J.

Saito A.

Mori D.

Tomita K.

Pan Y.

Tamura N.

Suzuki C.

Okuno H.

Guo F.

Namba S.

Journal of Applied Physics

For plasma window (PW) applications, we developed the cascade arc discharge device with an indirectly heated hollow cathode. The 8-mm channel diameter hollow cathode made of a lanthanum hexaboride (LaB ⁠) was heated by the C/C composite heater surrounding the cathode to increase the thermionic electron emission. The PW developed successfully separated 2.4 kPa and 16 Pa, and the pressure separation capability was sustained for over 1 h. H- Stark broadening measurement and the Thomson scattering measurement showed that the electron density and temperature inside the channel reached 1019-1020m-3 and 2.0 eV, respectively. The power balance analysis on the electron thermal energy revealed that the neutral density and temperature inside the channel were as high as 1023 m-3 and 4000 K, respectively. The relation between the pressure separation capability and the neutral temperature showed that the flow inside the channel of the PW had the molecular flow feature. The SEM-EDX analysis on the LaB cathode showed that boron diffused to the molybdenum (Mo) shaft during plasma operation, which supported the LaB cathode. Mo shaft became brittle after more than 50 h of operation, exhibiting the necessity of buffer material between the LaB cathode and Mo shaft for long-duration operation.

eng

AIP Publishing

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Yamasaki, K. et al., Development of a large-bore plasma window with an indirectly heated hollow cathode, Journal of Applied Physics, 134, 093302 (2023) and may be found at https://doi.org/10.1063/5.0166798.

This is not the published version. Please cite only the published version.

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[DOI] https://doi.org/10.1063/5.0166798 isVersionOf

日本学術振興会

Japan Society for the Promotion of Science

[Crossref Funder] https://doi.org/10.13039/501100001691

真空工学に革命的技術をもたらすプラズマウィンドウの開発と量子ビーム科学への応用

Development of plasma window for vacuum interface and its application to quantum beam science

20H00141