Polarization reversal of Alfvén waves in a non-axisymmetric region of a quadrupole-anchored tandem mirror

Inutake, M.; Ichimura, M.; Hōjō, H.; Kimura, Yoichi; Katsumata, R.; Adachi, Satoshi; Nakashima, Y.; Itakura, A.; Mase, A.; Miyoshi, S.

doi:10.1103/physrevlett.65.3397

Cited by 47 publications

(12 citation statements)

References 13 publications

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“…7,9 Being stimulated by our measurements, 11 experimental trials on this topic have also been made in the Gamma-10 tandem mirror 12 and small linear 13 devices, preliminary results of which support our work presented in this paper. In our experiment a set of dual half-turn antennas is used in an axisymmetric tandem mirror to excite rf fields around the ion cyclotron frequency, which azimuthally propagate in the direction of ion cyclotron (mϽ0) or electron cyclotron (mϾ0) motion in a plasma.…”

Section: Introductionsupporting

confidence: 73%

Measurements on rotating ion cyclotron range of frequencies induced particle fluxes in axisymmetric mirror plasmas

et al. 1997

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A comparison of phenomenological features of plasmas is made with a special emphasis on radio-frequency induced transport, which are maintained when a set of two closely spaced dual half-turn antennas in a central cell of the Phaedrus-B axisymmetric tandem mirror ͓J. J. Browning et al., Phys. Fluids B 1, 1692 ͑1989͔͒ is phased to excite electromagnetic fields in the ion cyclotron range of frequencies ͑ICRF͒ with mϭϪ1 ͑rotating with ions͒ and mϭϩ1 ͑rotating with electrons͒ azimuthal modes. Positive and negative electric currents are measured to flow axially to the end walls in the cases of mϭϪ1 and mϭϩ1 excitations, respectively. These parallel nonambipolar ion and electron fluxes are observed to be accompanied by azimuthal ion flows in the same directions as the antenna-excitation modes m. The phenomena are argued in terms of radial particle fluxes due to a nonambipolar transport mechanism ͓Hojo and Hatori, J. Phys. Soc. Jpn. 60, 2510 ͑1991͒; Hatakeyama et al., J. Phys. Soc. Jpn. 60, 2815 ͑1991͒, and Phys. Rev. E 52, 6664 ͑1995͔͒, which are induced when azimuthally traveling ICRF waves are absorbed in the magnetized plasma column.

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Section: Introductionsupporting

confidence: 73%

Measurements on rotating ion cyclotron range of frequencies induced particle fluxes in axisymmetric mirror plasmas

et al. 1997

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“…In normal discharges, the Type-III antennas in the central cell are used to produce the plasma in the central cell and to heat ions in both anchor cells [12,13]. The DHT antennas in the central cell are used to excite slow waves and heat ions near the midplane of the central cell.…”

Section: Methodsmentioning

confidence: 99%

Effect of the Potential of Confined Plasma on End-Loss Ion in GAMMA 10/PDX

Jang

Ichimura

Hirata

et al. 2019

Plasma and Fusion Research

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In the GAMMA 10/PDX tandem mirror, studies on divertor physics have been performed in the west end region by utilizing end-loss plasmas flowing from the confinement region. Since the plasma density in the end region is quite low (∼ 10 16 m −3), an increase of the end-loss ion flux is required. The increase of the end-loss ion flux has been obtained by increasing the density in the confinement region on previous experiments. When an additional ICRF heating using the antennas in the anchor cells has been performed, a significant increase of the ion flux has been observed with the increase of the potential in the central cell although the change of line densities in the confinement region is little. The effect of the potential on the ion flux has been examined on the GAMMA 10/PDX using about 10,000 discharges. The ion flux increases almost linearly with the potential and the density increase. By comparing with a simple calculation, the increase of the ion flux is explained by the expansion of loss cone boundary of ions and the decrease of the transport time of the end-loss ions from the confinement region to the end region.

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“…The phase difference has a positive value between 130 and 180 ms, which indicates that the DF-wave is right-handed polarized in the plasma periphery, while a negative value implies a left-handed polarized wave. This suggests that the DF-wave is excited as a left-handed polarized in the core plasma, as the rotation direction of plasma of Alfvén waves with m = ±1 in cylindrical plasma, like that in the GAMMA 10/PDX, is reversed between the radial inside and outside [9].…”

Section: Wave Measurementmentioning

confidence: 96%

Examination of High-Density Plasma Heating on the GAMMA 10/PDX Central Cell with 3D Wave Analysis Code

Kim

Hirata

Sugimoto

et al. 2023

Plasma and Fusion Research

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In GAMMA 10/PDX, ion heating is achieved using slow wave in the ion cyclotron frequency absorbed near the resonance layer. However, in high-density plasma, the slow wave is less likely to be excited due to the shielding effect. To overcome this challenge, researchers have investigated difference frequency (DF) waves excited by the nonlinear interaction of fast waves have been investigated. The fast waves can propagate to the core plasma even in high-density plasma making DF-waves an efficient option for ion heating. This study has suggested that a DF-wave with left-handed polarization, which is excited as a slow wave, is effective for ion heating in high-density plasma. The characteristics of the DF-wave were analyzed using a three-dimensional (3D) wave analysis code, TASK/WF3D, to investigate the ion resonance absorption of DF-wave heating. The results showed that when the antenna is positioned inside the core plasma to simulate DF-wave heating, ion resonance absorption is higher in high-density plasma than in low-density plasma. These results indicate that DF-wave heating is effective in high-density plasmas.

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Polarization reversal of Alfvén waves in a non-axisymmetric region of a quadrupole-anchored tandem mirror

Cited by 47 publications

References 13 publications

Measurements on rotating ion cyclotron range of frequencies induced particle fluxes in axisymmetric mirror plasmas

Measurements on rotating ion cyclotron range of frequencies induced particle fluxes in axisymmetric mirror plasmas

Effect of the Potential of Confined Plasma on End-Loss Ion in GAMMA 10/PDX

Examination of High-Density Plasma Heating on the GAMMA 10/PDX Central Cell with 3D Wave Analysis Code

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