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Your search keyword '"Yip, Chi-Shung"' showing total 38 results
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38 results on '"Yip, Chi-Shung"'

2. Instability enhanced thermalization of bi-Maxwellian EEDF in multi-dipole confined hot cathode discharge: an experimental observation.

Author

Jiang, Di, Yip, Chi-Shung, Jin, Chen-Yao, Zhang, Wei, Wang, Liang, and Xu, Guo-Sheng

Subjects
*THERMAL neutrons, *HOT carriers, *ELECTRON distribution, *DISTRIBUTION (Probability theory), *THERMAL equilibrium, *CATHODES
Abstract

In multi-dipole confined hot cathode discharges, the presence of up to three distinct electron species has been observed by performing linear fitting of the Langmuir probe I – V traces. Nevertheless, the fundamental mechanism underlying the generation of hot electrons remains ambiguous. This work presents experimental observations to comprehensively investigate the impact of the instability-enhanced thermalization effect on the thermal equilibrium of both hot and cold electrons. Temperature composition of the electron energy distribution function (EEDF) was measured via a Langmuir probe, while instabilities was measured using a spectrum analyzer. The experimental results confirm the existence of a transition from a three-temperature Maxwellian EEDF composition to a two-temperature Maxwellian EEDF composition as the population of high-energy electrons increases. Furthermore, the process of thermalization between hot and cold electrons is found to be correlated to the effect of instability-enhanced collisions. The intensity of collisional instability also decreases with increased neutral collisionality. [ABSTRACT FROM AUTHOR]

Published
2024
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21. A simple replacement of tungsten filament hot cathodes by DC heated LaB6 rod and its noise characteristics with laser-induced fluorescence.

Author

Jiang, Di, Yip, Chi-Shung, Zhang, Wei, Jin, Chen-yao, Xu, Guo-Sheng, and Wang, Liang

Subjects
*LASER-induced fluorescence, *TUNGSTEN, *CATHODES, *PLASMA physics, *FIBERS
Abstract

Hot cathode discharges are common plasma sources for fundamental plasma physics studies and other applications due to their quiescent and relatively simple properties, and tungsten filaments are commonly used for the ease of heating them. Recently, tungsten filaments are increasingly being replaced by less luminous alternatives, such as barium oxide or lanthanum hexaboride. These materials can emit electrons at temperatures close to 1000 K lower than tungsten, greatly reducing their blackbody radiations. This results in significant improvement in signal recovery for active spectral diagnostic, such as laser-induced fluorescence. However, these less luminous cathodes often come in vastly more complicated designs than those of tungsten hot cathodes and are much more expensive to procure and difficult to operate. In this paper, we present a simple, low cost direct current heated design of a LaB6 cathode that is manufactured at suitable dimensions and make a comparison of the laser-induced fluorescence (LIF) signal-to-noise ratio of this LaB6 hot cathode discharge with that of a typical tungsten filament discharge, revealing that LaB6 has, indeed, an improved LIF signal-to-noise ratio compared with the tungsten filament. [ABSTRACT FROM AUTHOR]

Published
2021
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38. A simple replacement of tungsten filament hot cathodes by DC heated LaB 6 rod and its noise characteristics with laser-induced fluorescence.

Author

Jiang D, Yip CS, Zhang W, Jin CY, Xu GS, and Wang L

Abstract

Hot cathode discharges are common plasma sources for fundamental plasma physics studies and other applications due to their quiescent and relatively simple properties, and tungsten filaments are commonly used for the ease of heating them. Recently, tungsten filaments are increasingly being replaced by less luminous alternatives, such as barium oxide or lanthanum hexaboride. These materials can emit electrons at temperatures close to 1000 K lower than tungsten, greatly reducing their blackbody radiations. This results in significant improvement in signal recovery for active spectral diagnostic, such as laser-induced fluorescence. However, these less luminous cathodes often come in vastly more complicated designs than those of tungsten hot cathodes and are much more expensive to procure and difficult to operate. In this paper, we present a simple, low cost direct current heated design of a LaB 6 cathode that is manufactured at suitable dimensions and make a comparison of the laser-induced fluorescence (LIF) signal-to-noise ratio of this LaB 6 hot cathode discharge with that of a typical tungsten filament discharge, revealing that LaB 6 has, indeed, an improved LIF signal-to-noise ratio compared with the tungsten filament.

Published
2021
Full Text
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