Optimization of the high harmonic ECRH scenario to extend a heating plasma parameter range in LHD

The LHD Experiment Group

    Research output: Contribution to journalArticle

    6 Citations (Scopus)

    Abstract

    Effectiveness of high harmonic electron cyclotron resonance heating (ECRH) was investigated by both experiments and ray-trace analyses. The conditions of both the EC wave injection and the magnetic field configuration were optimized in the large helical device. In the case of the second harmonic ordinary mode injection with a frequency of 77 GHz and with the optimized injection angle, about 30-40% absorption could be kept beyond the cut-off density of the second harmonic extraordinary (X2) mode, which is 3.7 × 1019 m-3. In the third harmonic X (X3) mode heating experiment, the dependence of the absorption rate on plasma density and temperature of the target plasma was precisely investigated and compared with the ray-trace (TRAVIS code) calculation. The calculation results of the absorption rate show fairly good agreement with the experimentally obtained ones on the plasma-parameter dependences. The maximum absorption rate in the X3 heating experiment attained approximately 40% around the electron density of 1.5 × 1019 m-3 and the electron temperature of 1.2 keV. Superposed stepwise injection from three gyrotrons with a total of 3 MW increased the central electron temperature to about 3.5 times of the initial target plasma temperature of 0.6 keV. This shows that the temperature increase improves the absorption rate of the subsequent injection.

    Original languageEnglish
    Article number063035
    JournalNuclear Fusion
    Volume55
    Issue number6
    DOIs
    Publication statusPublished - Jun 1 2015

    Fingerprint

    plasma heating
    electron cyclotron resonance
    injection
    harmonics
    optimization
    heating
    plasma temperature
    rays
    electron energy
    cyclotron resonance devices
    magnetic field configurations
    plasma density
    cut-off

    All Science Journal Classification (ASJC) codes

    • Nuclear and High Energy Physics
    • Condensed Matter Physics

    Cite this

    Optimization of the high harmonic ECRH scenario to extend a heating plasma parameter range in LHD. / The LHD Experiment Group.

    In: Nuclear Fusion, Vol. 55, No. 6, 063035, 01.06.2015.

    Research output: Contribution to journalArticle

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    title = "Optimization of the high harmonic ECRH scenario to extend a heating plasma parameter range in LHD",
    abstract = "Effectiveness of high harmonic electron cyclotron resonance heating (ECRH) was investigated by both experiments and ray-trace analyses. The conditions of both the EC wave injection and the magnetic field configuration were optimized in the large helical device. In the case of the second harmonic ordinary mode injection with a frequency of 77 GHz and with the optimized injection angle, about 30-40{\%} absorption could be kept beyond the cut-off density of the second harmonic extraordinary (X2) mode, which is 3.7 × 1019 m-3. In the third harmonic X (X3) mode heating experiment, the dependence of the absorption rate on plasma density and temperature of the target plasma was precisely investigated and compared with the ray-trace (TRAVIS code) calculation. The calculation results of the absorption rate show fairly good agreement with the experimentally obtained ones on the plasma-parameter dependences. The maximum absorption rate in the X3 heating experiment attained approximately 40{\%} around the electron density of 1.5 × 1019 m-3 and the electron temperature of 1.2 keV. Superposed stepwise injection from three gyrotrons with a total of 3 MW increased the central electron temperature to about 3.5 times of the initial target plasma temperature of 0.6 keV. This shows that the temperature increase improves the absorption rate of the subsequent injection.",
    author = "{The LHD Experiment Group} and T. Shimozuma and H. Igami and S. Kubo and Y. Yoshimura and H. Takahashi and M. Osakabe and T. Mutoh and M. Nishiura and H. Idei and K. Nagasaki and N. Marushchenko and Y. Turkin",
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    T1 - Optimization of the high harmonic ECRH scenario to extend a heating plasma parameter range in LHD

    AU - The LHD Experiment Group

    AU - Shimozuma, T.

    AU - Igami, H.

    AU - Kubo, S.

    AU - Yoshimura, Y.

    AU - Takahashi, H.

    AU - Osakabe, M.

    AU - Mutoh, T.

    AU - Nishiura, M.

    AU - Idei, H.

    AU - Nagasaki, K.

    AU - Marushchenko, N.

    AU - Turkin, Y.

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    Y1 - 2015/6/1

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    AB - Effectiveness of high harmonic electron cyclotron resonance heating (ECRH) was investigated by both experiments and ray-trace analyses. The conditions of both the EC wave injection and the magnetic field configuration were optimized in the large helical device. In the case of the second harmonic ordinary mode injection with a frequency of 77 GHz and with the optimized injection angle, about 30-40% absorption could be kept beyond the cut-off density of the second harmonic extraordinary (X2) mode, which is 3.7 × 1019 m-3. In the third harmonic X (X3) mode heating experiment, the dependence of the absorption rate on plasma density and temperature of the target plasma was precisely investigated and compared with the ray-trace (TRAVIS code) calculation. The calculation results of the absorption rate show fairly good agreement with the experimentally obtained ones on the plasma-parameter dependences. The maximum absorption rate in the X3 heating experiment attained approximately 40% around the electron density of 1.5 × 1019 m-3 and the electron temperature of 1.2 keV. Superposed stepwise injection from three gyrotrons with a total of 3 MW increased the central electron temperature to about 3.5 times of the initial target plasma temperature of 0.6 keV. This shows that the temperature increase improves the absorption rate of the subsequent injection.

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