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Space-charge-limited currents for cathodes with electric field enhanced geometry

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4959865· OSTI ID:22599984
; ;  [1];  [2]
  1. State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 701124 (China)
  2. Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)
This paper presents the approximate analytic solutions of current density for annulus and circle cathodes. The current densities of annulus and circle cathodes are derived approximately from first principles, which are in agreement with simulation results. The large scaling laws can predict current densities of high current vacuum diodes including annulus and circle cathodes in practical applications. In order to discuss the relationship between current density and electric field on cathode surface, the existing analytical solutions of currents for concentric cylinder and sphere diodes are fitted from existing solutions relating with electric field enhancement factors. It is found that the space-charge-limited current density for the cathode with electric-field enhanced geometry can be written in a general form of J = g(β{sub E}){sup 2}J{sub 0}, where J{sub 0} is the classical (1D) Child-Langmuir current density, β{sub E} is the electric field enhancement factor, and g is the geometrical correction factor depending on the cathode geometry.
OSTI ID:
22599984
Journal Information:
Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 23; ISSN PHPAEN; ISSN 1070-664X
Country of Publication:
United States
Language:
English

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