Mode Transition (πΌ β πΎ) and Hysteresis in Microwave-driven Low-temperature Plasmas
- Title
- Mode Transition (πΌ β πΎ) and Hysteresis in Microwave-driven Low-temperature Plasmas
- Authors
- κΉκ²½ν
- Date Issued
- 2022
- Publisher
- ν¬ν곡과λνκ΅
- Abstract
- μ ν¬ μ°κ΅¬μμλ μ μ μμ€ν
μμ μλ₯΄κ³€ λ§μ΄ν¬λ‘ν νλΌμ¦λ§μμ λ°©μ λͺ¨λ ( πΌ λ° πΎ λͺ¨λ) μ νμ κ±Έμ³ λ°μνλ νμ€ν
리μμ€λ₯Ό λ°κ²¬νμ΅λλ€. νμ€ν
리μμ€λ μλ ₯ λ³νμ λ°©ν₯μ λ°λΌ λ€λ₯Έ μκ³ μλ ₯μμ λͺ¨λ μ μ΄κ° λ°μνλ κ²μΌλ‘ λνλ©λλ€. λ°©μ λͺ¨λ μ νμ μλ₯΄κ³€ λ°©μΆ μ μ λΉκ΅νλ κ²μ ν΅ν΄ μΆμ ν μλ₯΄κ³€ μ΄μ¨λμ λ³ν λλ μ μ μ¨λμ κΈκ²©ν λ³νλ‘ νμΈνμμ΅λλ€. κ²°κ³Όμ μΌλ‘ μ£Όμ΄μ§ κ°μ μλ λ³μ( μλ ₯, νμ, κ°μ€ μ‘°μ± )μμ λ°©μ λͺ¨λκ° μλ ₯ λ³νμ λ°©ν₯μ λ°λΌ λ¬λΌμ§λ©°, μ΄ κ²°κ³Όλ κ°μ μλ 쑰건μ νλΌμ¦λ§ 곡μ κ³Όμ μμ λ€λ₯Έ νΉμ±μ κ°μ§ μ΄μ€ μμ μνμ μ‘΄μ¬ κ°λ₯μ±μ μ μν©λλ€. μ€νμμ κ΄μ°°λ νμ€ν
리μμ€λ OH(A-X) λ°©μΆ μ μμ μΈ‘μ λ νμ (rotational) λ° μ§λ(vibrational) μ¨λλ₯Ό μ‘°μ¬νμ¬ λΆμνμμ΅λλ€. κ°λ¨ν 물리μ λͺ¨λΈμ μ μ©νμ¬ νμ μ¨λμ λ³μ§ μ¨λ μ¬μ΄μ κ΄κ³λ₯Ό μ€λͺ
νκ³ , λͺ¨λ μ ν κ³Όμ μ νμ€ν
리μμ€λ πΎ λͺ¨λμμ λ°μνλ λΉ λ₯Έ κ°μ€ κ°μ΄λ‘ μΈν΄μ λνλλ κ²μΌλ‘ λΆμνμμ΅λλ€. μ¦, πΎ λͺ¨λμ λΉ λ₯Έ κ°μ€ κ°μ΄λ‘ μ€μ± λ°λλ πΌ λͺ¨λμ μ€μ± λ°λλ³΄λ€ μκ² μ μ§λλ©°, πΌ μμ πΎ λͺ¨λλ‘μ μ μ΄ κ³Όμ μ λΉν΄ μμ€ν
μ μλ ₯μ΄ μ¦κ° λ πΎ μμ πΌ λͺ¨λλ‘μ μ μ΄ κ²½μ°μ μλ ₯μ΄ κ°μνλ κ³Όμ λ³΄λ€ λ λμ μκ³ μλ ₯μ΄ νμνκ² λ©λλ€. μ΄ ν΄μμ μλ ₯ λμ μ€μ± λ°λλ‘ ν΄μνμ λ, νμ€ν
리μμ€κ° μ¬λΌμ§λ κ²μ ν΅ν΄μ κ²μ¦λ©λλ€.
We discovered hysteresis in microwave-driven low-pressure Ar plasmas across the transition of discharge modes (πΌ and πΎ). The hysteresis manifests as two different mode transition pressures depending on the direction of the pressure change. The discharge mode transition is identified by a rapid change in the argon ion population or electron temperature (both are estimated from the Ar emission lines). As a corollary, the discharge characteristics at given operation parameters (pressure, power, and gas composition) depend on the direction of pressure change, suggesting the possibility of bistable states in processing plasmas. The hysteresis observed in the experiment was analyzed by investigating the rotational and vibrational temperatures measured from the OH (A-X) emission lines. Additionally, the relationship between the rotational and translational temperatures was explained by applying simple physical models. It was shown that the hysteresis during mode transition occurs because of fast gas heating in the πΎ mode owing to the larger amplitude collective oscillations. As a result, the neutral density of the πΎ mode is smaller than that of the Ξ± mode, and a higher critical pressure is required for the πΎ to πΌ transition when the system pressure increases as compared to the case of the πΌ to πΎ transition where system pressure decreases. This interpretation is confirmed by the elimination of hysteresis by analyzing it in neutral density instead of pressure.
- URI
- http://postech.dcollection.net/common/orgView/200000599978
https://oasis.postech.ac.kr/handle/2014.oak/112118
- Article Type
- Thesis
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