f c r , the phase-space plots indicate that the electrons are confined inside the gap, causing the electron number to grow exponentially and v i / p to become a function of E e f f / p. These results elucidate the ionization mechanism for AC fields at microscale gap distances and may be incorporated into field emission-driven microwave breakdown theories to improve their predictive capability. [ABSTRACT FROM AUTHOR]
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| Autor: |
Wang, Haoxuan, Venkattraman, Ayyaswamy, Loveless, Amanda M., Garner, Allen L. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 9/14/2023, Vol. 134 Issue 10, p1-10, 10p |
| Abstrakt: |
The importance of microwave device reliability and performance for microscale devices motivates a more fundamental understanding of breakdown mechanisms in this regime. Microwave breakdown theories predict breakdown when electron production balances electron loss. Electron production depends strongly on the ionization rate ν i ; however, previous studies either used the measured ν i in macroscale gaps or the empirical formula for DC voltage, inaccurately predicting ν i in microscale gaps. Alternatively, this work characterizes ν i in microwave microplasmas by using particle-in-cell simulations. We calculated ν i in argon gas at atmospheric pressure for 2–10 μm gaps under AC fields ranging from 1 to 1000 GHz. The behavior of ν i may be separated into two regimes by defining a critical frequency f c r that depends on the amplitude of the applied voltage, gap distance, and pressure. For frequency f < f c r , the electrodes collect the electrons during each cycle and the electron number oscillates with the electric field, causing ν i / f to roughly scale with the reduced effective field E e f f / p. For f > --> f c r , the phase-space plots indicate that the electrons are confined inside the gap, causing the electron number to grow exponentially and v i / p to become a function of E e f f / p. These results elucidate the ionization mechanism for AC fields at microscale gap distances and may be incorporated into field emission-driven microwave breakdown theories to improve their predictive capability. [ABSTRACT FROM AUTHOR] |
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