Influence of emission threshold of explosive emission cathodes on current waveform in foilless diodes

Journal Article · Sat Aug 15 04:00:00 EDT 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4928090· OSTI ID:22490077

Wu, P.; Liu, G. Z. ^[1]; Huo, S. F.; Sun, J.; Chen, C. H. ^[2]

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1. Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)
2. Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

The emission threshold of explosive emission cathodes (EECs) is an important factor for beam quality. It can affect the explosive emission delay time, the plasma expansion process on the cathode surface, and even the current amplitude when the current is not fully space-charge-limited. This paper researches the influence of the emission threshold of an annular EEC on the current waveform in a foilless diode when the current is measured by a Rogowski coil. The particle-in-cell simulation which is performed under some tolerable and necessary simplifications shows that the long explosive emission delay time of high-threshold cathodes may leave an apparent peak of displacement current on the rise edge of the current waveform, and this will occur only when the electron emission starts after this peak. The experimental researches, which are performed under a diode voltage of 1 MV and a repetitive frequency of 20 Hz, demonstrate that the graphite cathode has a lower emission threshold and a longer lifetime than the stainless steel cathode according to the variation of the peak of displacement current on the rise edge of the current waveform.

• OSTI ID: 22490077
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 22; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AMPLITUDES
BEAM PRODUCTION
CATHODES
CURRENTS
ELECTRIC POTENTIAL
ELECTRON EMISSION
GRAPHITE
PLASMA EXPANSION
PLASMA SIMULATION
ROGOWSKI COIL
SPACE CHARGE
STAINLESS STEELS
TIME DELAY
WAVE FORMS