Hybrid simulation of electrode plasmas in high-power diodes

Dale R. Welch; David V. Rose; Nichelle Bruner; Robert E. Clark; Bryan V. Oliver; Kelly D. Hahn; Mark D. Johnston

doi:10.1063/1.3270471

Hybrid simulation of electrode plasmas in high-power diodes

Physics of Plasmas ◽

10.1063/1.3270471 ◽

2009 ◽

Vol 16 (12) ◽

pp. 123102 ◽

Cited By ~ 37

Author(s):

Dale R. Welch ◽

David V. Rose ◽

Nichelle Bruner ◽

Robert E. Clark ◽

Bryan V. Oliver ◽

...

Keyword(s):

High Power ◽

Hybrid Simulation ◽

Power Diodes

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Electrode shapes for high‐power diodes with non‐space‐charge‐limited flow

Journal of Applied Physics ◽

10.1063/1.350963 ◽

1992 ◽

Vol 71 (7) ◽

pp. 3197-3200

Author(s):

William Peter

Keyword(s):

Space Charge ◽

High Power ◽

Power Diodes ◽

Space Charge Limited

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Time evolution of the two-dimensional expansion velocity distributions of the cathode plasma in pulsed high-power diodes

Laser and Particle Beams ◽

10.1017/s0263034612001127 ◽

2013 ◽

Vol 31 (1) ◽

pp. 129-134 ◽

Cited By ~ 15

Author(s):

Jie Yang ◽

Ting Shu ◽

Yuwei Fan

Keyword(s):

High Power ◽

Cathode Surface ◽

Transverse Velocity ◽

Longitudinal Velocity ◽

Expansion Velocity ◽

Two Dimensional ◽

Plasma Expansion ◽

Cathode Plasma ◽

Power Diodes ◽

Diode Current

AbstractA combination of electrical and optical diagnostics has been used to investigate the time evolution of the two-dimensional expansion velocity distributions of the cathode plasma in pulsed high-power diodes. The perveance model based on the Child-Langmuir law was used to calculate the expansion velocity of the diode plasmas from voltage and current profiles. Additionally, a four-channel high speed framing camera was used to observe the formation and subsequent movement of the cathode plasma. More accurate and valuable information about the dynamics of the cathode plasma was also acquired by utilizing the digital image processing methods. Results from the experiments and theoretical analysis were compared. In this paper, the experiments have been performed using a high-voltage pulse generator with 200 kV output voltage and 110 ns pulse duration. Current densities up to 440 A/cm2were produced. The observation of the cathode plasma expansion in transverse direction indicated that the diode current was cathode-limited in the current rising stage (the first 60 ns of the current pulse). The perveance model should be modified taking in account the time dependent expanding plasma surface (i.e., not the whole cathode surface) for this period. The velocity in the direction parallel to the cathode surface (transverse velocity) was much larger than that in the direction perpendicular to the cathode surface (longitudinal velocity), and further, it dropped from 90 cm/μs to nearly 20 cm/μs rapidly. It was shown that, during the current flattop stage, the plasma filled out all the surface of cathode and the diode current was space-charge-limited. The values of the transverse velocity and longitudinal velocity were nearly the same and decreased relatively slowly. The satisfactory coincidence of experimental and calculated (both were in the range of 6–8 cm/μs) values of the cathode plasma expansion velocities was obtained.

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