Spatial profile of argon (1s5) metastables in an electron beam generated plasma

K. Kondeti, V. S. Santosh; Chopra, Nirbhav S.; Yatom, Shurik; Raitses, Yevgeny

doi:10.1088/1361-6595/ae186f

Spatial profile of argon (1s₅) metastables in an electron beam generated plasma

Journal Article · Mon Nov 24 00:00:00 EST 2025 · Plasma Sources Science and Technology

DOI:https://doi.org/10.1088/1361-6595/ae186f· OSTI ID:3006375

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Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Electron beams with an applied magnetic field generate a secondary cold plasma with a selective chemical composition, featuring low-energy ions and metastable species in the discharge periphery, ideal for low-damage plasma treatment of material substrates. In this work, we studied the plasma generated by an e-beam using a 4 kV voltage in a pure argon gas environment under a magnetic field of 150 G and in the pressure range of 25–90 mTorr. We measured the absolute spatial density profile of argon (1 s₅) metastables in an electron beam generated plasma by laser-induced fluorescence and found it to be of the order of 10¹⁶ m⁻³. The electron temperature and the electron density measured by a Langmuir probe were of the order of 10¹⁶ m⁻³ and less than an eV respectively. Electron-impact quenching was identified as a significant loss mechanism for the Ar(1s₅) state, leading to the saturation of the metastable density at higher pressures. Outside the primary ionization region, the spatial distribution of argon metastables followed a linear diffusion profile, indicating negligible additional production in those regions.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: AC02-09CH11466

OSTI ID:: 3006375

Journal Information:: Plasma Sources Science and Technology, Journal Name: Plasma Sources Science and Technology Journal Issue: 11 Vol. 34; ISSN 1361-6595; ISSN 0963-0252

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: United States

Language:: English

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