The importance of thermal dissociation in CO2 microwave discharges investigated by power pulsing and rotational Raman scattering

Dirk C.M. van den Bekerom, Jose M. Palomares Linares, Tiny Verreycken, Eddie M. van Veldhuizen, Sander Nijdam, G. Berden, Waldo A. Bongers, M.C.M. van de Sanden, Gerard J. van Rooij (Corresponding author)

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The input power of a CO2 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 ${\rm{K}}$, while the edge temperature remains cold (500 ${\rm{K}}$). During the plasma 'OFF'-period, the gas cools down convectively, but remains overall too hot to allow for strong overpopulation of vibrational modes (2200 ${\rm{K}}$ 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 CO2, to reflect on earlier reported record efficiencies of 90%.
TaalEngels
Artikelnummer055015
Aantal pagina's14
TijdschriftPlasma Sources Science and Technology
Volume28
Nummer van het tijdschrift5
DOI's
StatusGepubliceerd - mei 2019

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    @article{5b58923b3e4747ceb5186b68007752d9,
    title = "The importance of thermal dissociation in CO2 microwave discharges investigated by power pulsing and rotational Raman scattering",
    abstract = "The input power of a CO2 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 ${\rm{K}}$, while the edge temperature remains cold (500 ${\rm{K}}$). During the plasma 'OFF'-period, the gas cools down convectively, but remains overall too hot to allow for strong overpopulation of vibrational modes (2200 ${\rm{K}}$ 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 CO2, to reflect on earlier reported record efficiencies of 90{\%}.",
    keywords = "carbon dioxide, microwave plasma, rotational Raman, vibrational excitation non-equilibrium, gas conversion",
    author = "{van den Bekerom}, {Dirk C.M.} and {Palomares Linares}, {Jose M.} and Tiny Verreycken and {van Veldhuizen}, {Eddie M.} and Sander Nijdam and G. Berden and Bongers, {Waldo A.} and {van de Sanden}, M.C.M. and {van Rooij}, {Gerard J.}",
    year = "2019",
    month = "5",
    doi = "10.1088/1361-6595/aaf519",
    language = "English",
    volume = "28",
    journal = "Plasma Sources Science and Technology",
    issn = "0963-0252",
    publisher = "Institute of Physics",
    number = "5",

    }

    The importance of thermal dissociation in CO2 microwave discharges investigated by power pulsing and rotational Raman scattering. / van den Bekerom, Dirk C.M.; Palomares Linares, Jose M.; Verreycken, Tiny; van Veldhuizen, Eddie M.; Nijdam, Sander; Berden, G.; Bongers, Waldo A.; van de Sanden, M.C.M.; van Rooij, Gerard J. (Corresponding author).

    In: Plasma Sources Science and Technology, Vol. 28, Nr. 5, 055015, 05.2019.

    Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

    TY - JOUR

    T1 - The importance of thermal dissociation in CO2 microwave discharges investigated by power pulsing and rotational Raman scattering

    AU - van den Bekerom,Dirk C.M.

    AU - Palomares Linares,Jose M.

    AU - Verreycken,Tiny

    AU - van Veldhuizen,Eddie M.

    AU - Nijdam,Sander

    AU - Berden,G.

    AU - Bongers,Waldo A.

    AU - van de Sanden,M.C.M.

    AU - van Rooij,Gerard J.

    PY - 2019/5

    Y1 - 2019/5

    N2 - The input power of a CO2 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 ${\rm{K}}$, while the edge temperature remains cold (500 ${\rm{K}}$). During the plasma 'OFF'-period, the gas cools down convectively, but remains overall too hot to allow for strong overpopulation of vibrational modes (2200 ${\rm{K}}$ 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 CO2, to reflect on earlier reported record efficiencies of 90%.

    AB - The input power of a CO2 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 ${\rm{K}}$, while the edge temperature remains cold (500 ${\rm{K}}$). During the plasma 'OFF'-period, the gas cools down convectively, but remains overall too hot to allow for strong overpopulation of vibrational modes (2200 ${\rm{K}}$ 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 CO2, to reflect on earlier reported record efficiencies of 90%.

    KW - carbon dioxide

    KW - microwave plasma

    KW - rotational Raman

    KW - vibrational excitation non-equilibrium

    KW - gas conversion

    U2 - 10.1088/1361-6595/aaf519

    DO - 10.1088/1361-6595/aaf519

    M3 - Article

    VL - 28

    JO - Plasma Sources Science and Technology

    T2 - Plasma Sources Science and Technology

    JF - Plasma Sources Science and Technology

    SN - 0963-0252

    IS - 5

    M1 - 055015

    ER -