Edge turbulence measurement in Heliotron J using a combination of hybrid probe system and fast cameras

Nishino, Norikazu; Zang, L.; Takeuchi, Masaki; Mizuuchi, T.; Ohshima, S.; Kasajima, K.; Sha, M.; Mukai, K.; Lee, H.Y.; Nagasaki, K.; Okada, H.; Minami, Takashi; Kobayashi, S.; Yamamoto, Satoshi; Konoshima, S.; Nakamura, Yuji; Sano, F.

doi:10.1016/j.jnucmat.2013.01.112

Cited by 5 publications

(4 citation statements)

References 33 publications

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“…A combined GPI and Langmuir probe was also used on the Heliotron J stellarator, where turbulent bursts of I sat fluctuations were accompanied by filamentary structures seen along the B field in GPI. 90,91 To our knowledge no local comparisons of GPI and probes have been made in a tokamak although a high correlation was found between passive imaging of edge filaments and nearby probe signals in the Caltech 8 tokamak and in MAST. 34 …”

Section: A Gpi Vs Langmuir Probesmentioning

confidence: 94%

“…90,91 On the Gamma 10 mirror machine in Japan, the GPI puff emission was compared with DEGAS neutral simulation code in the mirror machine geometry. 92,93 On the NSTX spherical tokamak in the US, a single GPI sightline views a gas puff manifold located just above the outer midplane through a re-entrant window port.…”

Section: E Special Features Of Various Gpi Systemsmentioning

confidence: 99%

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Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Zweben

Terry

Stotler

et al. 2017

Review of Scientific Instruments

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Gas puff imaging (GPI) is a diagnostic of plasma turbulence which uses a puff of neutral gas at the plasma edge to increase the local visible light emission for improved space-time resolution of plasma fluctuations. This paper reviews gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion research, with a focus on the instrumentation, diagnostic cross-checks, and interpretation issues. The gas puff imaging hardware, optics, and detectors are described for about 10 GPI systems implemented over the past ∼15 years. Comparison of GPI results with other edge turbulence diagnostic results is described, and many common features are observed. Several issues in the interpretation of GPI measurements are discussed, and potential improvements in hardware and modeling are suggested.

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Section: A Gpi Vs Langmuir Probesmentioning

confidence: 94%

Section: E Special Features Of Various Gpi Systemsmentioning

confidence: 99%

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Zweben

Terry

Stotler

et al. 2017

Review of Scientific Instruments

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“…The BES is routinely used to identify the radial location of MHD modes in Heliotron J [37,38,44]. A perpendicularly viewed gas-puffing imaging (GPI) system is installed at the #14.5 section to observe the edge density fluctuation [45,46]. The object lens is focused on the top part of the last closed flux surface (LCFS) in the #14.5 section.…”

Section: Diagnostics and Analysis Techniquesmentioning

confidence: 99%

“…A perpendicular-viewed GPI system could also observe the LF-mode structure in the toroidal-poloidal plane [45,46]. The setup of the GPI system is illustrated in figure 7(a).…”

Section: Mode Structurementioning

confidence: 99%

Observation of a beam-driven low-frequency mode in Heliotron J

et al. 2019

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A low-frequency electromagnetic mode (LF-mode) has been observed in a stellarator/heliotron device, Heliotron J. The LF-mode is observed only in neutral beam heated plasmas with a co-current, which increases the rotational transform. The observed LF-mode peaks at rho = 0.86–0.91, where rho = r/a is the normalized minor radius. The LF-mode propagates in the ion diamagnetic drift direction, and the poloidal mode number is m ~ 6–8, determined with a combination of Mirnov coil arrays and 2D fast camera measurement. A high m number induces significant Doppler shift from the background ion flow. The frequency is corrected with both E × B rotation and the ion diamagnetic flow. The corrected frequency is almost consistent with the beta-induced Alfvén eigenmode gap evaluated with the STELLGAP code, although very close to the accumulation point. The mode could also be a global Alfvén eigenmode.

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