Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX

R. Sekine; M. Hirata; R. Ikezoe; S. Jang; Y. Kubota; H. Kayano; K. Sugata; T. Aizawa; D. Noguchi; D. Kim; Y. Sugimoto; R. Matsuura; H. Yamazaki; M. Ichimura; M. Yoshikawa; J. Kohagura; Y. Nakashima; N. Ezumi; M. Sakamoto

doi:10.1063/5.0043821

Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX

R. Sekine, M. Hirata, R. Ikezoe, S. Jang, Y. Kubota, H. Kayano, K. Sugata, T. Aizawa, D. Noguchi, D. Kim, Y. Sugimoto, R. Matsuura, H. Yamazaki, M. Ichimura, M. Yoshikawa, J. Kohagura, Y. Nakashima, N. Ezumi, M. Sakamoto

Advanced Fusion Research Center

Research output: Contribution to journal › Article › peer-review

Abstract

In the GAMMA 10/PDX tandem mirror, plasma with strong ion-temperature anisotropy is produced by using the ion cyclotron range of frequency waves. This anisotropy of ion temperature causes several Alfvén-Ion-Cyclotron (AIC) waves to spontaneously excite in the frequency range just below the ion cyclotron frequency. In addition, difference-frequency (DF) waves are excited in the radial inner region of the plasma by wave-wave coupling among the AIC waves. The radial density profiles were measured at multi-axial positions using a frequency-modulation reflectometer with an axial array of microwave antennas, and an axial variation of the density was found to be significant. In addition, a relative phase difference of the DF wave between axially separated two points was first obtained by finely choosing the probing frequency of the reflectometers with a maximum coherence used as a measure, indicating that the DF wave is a propagating wave, while the pump AIC waves are standing waves in the axial region of measurement.

Original language	English
Article number	053506
Journal	Review of Scientific Instruments
Volume	92
Issue number	5
DOIs	https://doi.org/10.1063/5.0043821
Publication status	Published - May 1 2021

All Science Journal Classification (ASJC) codes

Instrumentation

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Sekine, R., Hirata, M., Ikezoe, R., Jang, S., Kubota, Y., Kayano, H., Sugata, K., Aizawa, T., Noguchi, D., Kim, D., Sugimoto, Y., Matsuura, R., Yamazaki, H., Ichimura, M., Yoshikawa, M., Kohagura, J., Nakashima, Y., Ezumi, N., & Sakamoto, M. (2021). Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX. Review of Scientific Instruments, 92(5), Article 053506. https://doi.org/10.1063/5.0043821

Sekine, R, Hirata, M, Ikezoe, R, Jang, S, Kubota, Y, Kayano, H, Sugata, K, Aizawa, T, Noguchi, D, Kim, D, Sugimoto, Y, Matsuura, R, Yamazaki, H, Ichimura, M, Yoshikawa, M, Kohagura, J, Nakashima, Y, Ezumi, N & Sakamoto, M 2021, 'Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX', Review of Scientific Instruments, vol. 92, no. 5, 053506. https://doi.org/10.1063/5.0043821

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title = "Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX",

abstract = "In the GAMMA 10/PDX tandem mirror, plasma with strong ion-temperature anisotropy is produced by using the ion cyclotron range of frequency waves. This anisotropy of ion temperature causes several Alfv{\'e}n-Ion-Cyclotron (AIC) waves to spontaneously excite in the frequency range just below the ion cyclotron frequency. In addition, difference-frequency (DF) waves are excited in the radial inner region of the plasma by wave-wave coupling among the AIC waves. The radial density profiles were measured at multi-axial positions using a frequency-modulation reflectometer with an axial array of microwave antennas, and an axial variation of the density was found to be significant. In addition, a relative phase difference of the DF wave between axially separated two points was first obtained by finely choosing the probing frequency of the reflectometers with a maximum coherence used as a measure, indicating that the DF wave is a propagating wave, while the pump AIC waves are standing waves in the axial region of measurement.",

author = "R. Sekine and M. Hirata and R. Ikezoe and S. Jang and Y. Kubota and H. Kayano and K. Sugata and T. Aizawa and D. Noguchi and D. Kim and Y. Sugimoto and R. Matsuura and H. Yamazaki and M. Ichimura and M. Yoshikawa and J. Kohagura and Y. Nakashima and N. Ezumi and M. Sakamoto",

note = "Funding Information: The authors would like to thank the GAMMA 10 group at the University of Tsukuba for their collaboration in the experiments and for helpful discussions. This work was partly supported by the bidirectional collaborative research program of the National Institute for Fusion Science, Japan (Grant Nos. NIFS20KUGM148, NIFS20KUGM158, and NIFS19KUGM141). Publisher Copyright: {\textcopyright} 2021 Author(s).",

year = "2021",

month = may,

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doi = "10.1063/5.0043821",

language = "English",

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T1 - Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX

AU - Sekine, R.

AU - Hirata, M.

AU - Ikezoe, R.

AU - Jang, S.

AU - Kubota, Y.

AU - Kayano, H.

AU - Sugata, K.

AU - Aizawa, T.

AU - Noguchi, D.

AU - Kim, D.

AU - Sugimoto, Y.

AU - Matsuura, R.

AU - Yamazaki, H.

AU - Ichimura, M.

AU - Yoshikawa, M.

AU - Kohagura, J.

AU - Nakashima, Y.

AU - Ezumi, N.

AU - Sakamoto, M.

N1 - Funding Information: The authors would like to thank the GAMMA 10 group at the University of Tsukuba for their collaboration in the experiments and for helpful discussions. This work was partly supported by the bidirectional collaborative research program of the National Institute for Fusion Science, Japan (Grant Nos. NIFS20KUGM148, NIFS20KUGM158, and NIFS19KUGM141). Publisher Copyright: © 2021 Author(s).

PY - 2021/5/1

Y1 - 2021/5/1

N2 - In the GAMMA 10/PDX tandem mirror, plasma with strong ion-temperature anisotropy is produced by using the ion cyclotron range of frequency waves. This anisotropy of ion temperature causes several Alfvén-Ion-Cyclotron (AIC) waves to spontaneously excite in the frequency range just below the ion cyclotron frequency. In addition, difference-frequency (DF) waves are excited in the radial inner region of the plasma by wave-wave coupling among the AIC waves. The radial density profiles were measured at multi-axial positions using a frequency-modulation reflectometer with an axial array of microwave antennas, and an axial variation of the density was found to be significant. In addition, a relative phase difference of the DF wave between axially separated two points was first obtained by finely choosing the probing frequency of the reflectometers with a maximum coherence used as a measure, indicating that the DF wave is a propagating wave, while the pump AIC waves are standing waves in the axial region of measurement.

AB - In the GAMMA 10/PDX tandem mirror, plasma with strong ion-temperature anisotropy is produced by using the ion cyclotron range of frequency waves. This anisotropy of ion temperature causes several Alfvén-Ion-Cyclotron (AIC) waves to spontaneously excite in the frequency range just below the ion cyclotron frequency. In addition, difference-frequency (DF) waves are excited in the radial inner region of the plasma by wave-wave coupling among the AIC waves. The radial density profiles were measured at multi-axial positions using a frequency-modulation reflectometer with an axial array of microwave antennas, and an axial variation of the density was found to be significant. In addition, a relative phase difference of the DF wave between axially separated two points was first obtained by finely choosing the probing frequency of the reflectometers with a maximum coherence used as a measure, indicating that the DF wave is a propagating wave, while the pump AIC waves are standing waves in the axial region of measurement.

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Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX

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