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Simulations of argon plasma decay in a thermionic converter
R E Groenewald1, S Clark1, A Kannan1
1Modern Electron Inc., Bothell, Washington 98011, USA.
Physical Review. E
|March 19, 2021
Summary
Particle-in-cell simulations reveal differences in argon plasma decay between 1D and 2D thermionic diodes. This study suggests a new method for measuring cathode and anode work functions in thermionic converters.
Area of Science:
- Plasma physics
- Condensed matter physics
- Computational physics
Background:
- Thermionic diodes are crucial for energy conversion.
- Understanding plasma dynamics in these diodes is essential for efficiency.
- Plasma decay due to surface recombination affects diode performance.
Purpose of the Study:
- To investigate argon plasma dynamics in a thermionic diode using particle-in-cell (PIC) simulations.
- To analyze the time-averaged diode current as plasma density depletes.
- To compare plasma decay and current characteristics in one-dimensional (1D) and two-dimensional (2D) simulations.
Main Methods:
- Particle-in-cell (PIC) simulations were employed.
- Simulations were conducted in both 1D and 2D configurations.
- The study analyzed the time-averaged diode current as a function of electrode potential and plasma density depletion.
Main Results:
- Significant differences in plasma decay were observed between 1D and 2D simulations.
- In 2D, electrostatic potential changed gradually during plasma decay.
- In 1D, plasma fluctuations caused large potential fluctuations, altering decay characteristics and diode current.
Conclusions:
- 1D and 2D simulations yield different plasma decay behaviors and diode current characteristics.
- Maximum time-averaged current is achieved at the flat-band condition (equal cathode and anode vacuum biases).
- This finding suggests a novel method for measuring work function differences between thermionic converter electrodes.
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