Observation of non-thermal metastable ion velocity distributions in a miniaturized multi-dipole confined plasma device

Hot cathode discharges are common plasma sources for fundamental plasma physics studies and other applications due to their capability to produce quiescent plasma. This work presents experimental observations of presheath-associated non-thermal metastable ion velocity distributions in a miniaturized...

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Bibliographic Details
Published in:Physics of plasmas 2022-06, Vol.29 (6)
Main Authors: Jiang, Di, Yip, Chi-Shung, Jin, Chen-Yao, Zhang, Wei, Wang, Liang, Xu, Guo-Sheng
Format: Article
Language:English
Subjects:
Acceleration
Dipoles
Flow velocity
Hot cathodes
Ion velocity
Laser induced fluorescence
Plasma physics
Voltage drop
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Summary:Hot cathode discharges are common plasma sources for fundamental plasma physics studies and other applications due to their capability to produce quiescent plasma. This work presents experimental observations of presheath-associated non-thermal metastable ion velocity distributions in a miniaturized multi-dipole confined plasma device measured by laser-induced fluorescence. The intensity of this non-Maxwellian component is related to the collisions of these metastable ions with background particles. Additionally, the flow velocity of this component is lower than the Bohm velocity; thus, its energy is lower than the presheath potential drop kTe/2. This implies that these non-thermal metastable ion velocity distributions are formed via presheath acceleration and are associated with the source asymmetries of the miniaturized device. The strength decreases as the neutral pressure increases once the neutral pressure is adjusted, suggesting that the presheath length is the critical condition that determines whether these components can be observed.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0090948