The importance of thermal dissociation in CO2 microwave discharges investigated by power pulsing and rotational Raman scattering
| Autor: | M.C.M. van de Sanden, T Tiny Verreycken, S Sander Nijdam, W.A. Bongers, Giel Berden, Jose M. Palomares Linares, Dirk van den Bekerom, Eddie van Veldhuizen, Gerard van Rooij |
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| Přispěvatelé: | Plasma & Materials Processing, Elementary Processes in Gas Discharges, Extreme non-equilibrium plasmas |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
FELIX Molecular Structure and Dynamics
010302 applied physics Materials science rotational Raman gas conversion carbon dioxide Rotational temperature Plasma Condensed Matter Physics 01 natural sciences Dissociation (chemistry) 010305 fluids & plasmas symbols.namesake microwave plasma Molecular vibration Excited state 0103 physical sciences symbols vibrational excitation non-equilibrium Atomic physics Microwave Raman scattering Power density |
| Zdroj: | Plasma Sources Science and Technology, 28(5):055015. Institute of Physics Plasma Sources Sciences and Technology, 28 Plasma Sources Science and Technology, 28, 055015 Plasma Sources Sciences and Technology, 28, 5 |
| ISSN: | 0963-0252 |
| Popis: | The input power of a CO 2 microwave plasma is modulated at kHz rate in scans of duty cycle at constant average power to investigate gas heating dynamics and its relation to dissociation efficiency. Rotational temperature profiles obtained from rotational Raman scattering reveal peak temperatures of up to 3000 , while the edge temperature remains cold (500 ). During the plasma 'OFF'-period, the gas cools down convectively, but remains overall too hot to allow for strong overpopulation of vibrational modes (2200 in the core). Fast optical imaging monitors plasma volume variations and shows that power density scales with peak power. As dissociation scales with observed peak rotational temperature, it is concluded that thermal processes dominate. A simple 0D model is constructed which explains how higher power density favors dissociation over radial energy transport. Thermal decomposition is reviewed in relation to quenching oxygen radicals with vibrationally excited CO 2, to reflect on earlier reported record efficiencies of 90%. |
| Databáze: | OpenAIRE |
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