Low-pressure Cs-Ba discharge. I. Model development

Luke, James R.; El‐Genk, Mohamed S.

doi:10.1063/1.359941

Cited by 3 publications

References 7 publications

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Low-pressure Cs-Ba discharge. II. Probe measurements

Luke

El‐Genk

1995

Journal of Applied Physics

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Experiments are performed using Langmuir probes to measure the plasma parameters in both steady-state and I-V modes in a low-pressure Cs-Ba diode. The data show that at low discharge currents the electron energy distribution function is nonMaxwellian due to the presence of an electron beam from the emitter. Also, the plasma properties were nonhomogeneous across the 1 mm diode gap; the electron temperature was 10%–15% higher and the plasma potential ∼1 V higher near the emitter, and the plasma density was a factor of three higher near the collector. The good agreement between calculations and experiment, in spite of the presence of the electron beam from the emitter, suggested that the beam electrons do not undergo collisions with Cs atoms in the gap. Experimental I-V curves showed the presence of two different thermal emission currents, each corresponding to a different emitter work function, at the beginning and the end of the I-V pulse.

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Low-pressure Cs-Ba discharge. II. Probe measurements

Luke

El‐Genk

1995

Journal of Applied Physics

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Langmuir probe measurements of discharge parameters in a Cs–Ba tacitron

Luke¹,

El‐Genk²

1996

Journal of Applied Physics

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Experimental measurements of steady-state discharge parameters are performed in a Cs–Ba tacitron equipped with Langmuir probes. Measured quantities include electron temperature, plasma density, and plasma potential, in both the emitter-grid and grid-collector regions. The effects of Cs pressure and electrode arrangements on the measured parameters are investigated. Measurements indicate that the electron energy distribution function in the emitter-grid gap is Maxwellian, and that there is an electron beam in the grid-collector gap, which relaxes to Maxwellian at high cesium pressure. Placing the grid closer to the collector not only increases the ion loss rate, but also makes ionization inefficient, lowering the plasma density in the grid-collector gap. The low plasma density makes it easier to extinguish the discharge during current modulation.

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