Impact of helium neutral gas puff on plasma turbulence in linear magnetized argon plasmas

Kobayashi, Tatsuya; Kin, Fumiyoshi; Kawachi, Yuichi; Sasaki, M.; Kosuga, Y.; Yamasaki, K.; Inagaki, S.

doi:10.1063/5.0007899

Cited by 4 publications

(1 citation statement)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The proposed mechanism of the neutral effect can be important. Recently, neutral particle control experiment has been performed without changing the plasma profiles by using the gas-puffing, and the increase of the fluctuation with the neutral particles is observed [30]. The validation of the present mechanism is desired in such kind of experiments.…”

Section: Stability Of Pvg Including Neutral Particle Dragmentioning

confidence: 89%

Neutral particle drag on parallel flow shear driven instability

et al. 2020

Self Cite

View full text Add to dashboard Cite

Neutral drag effect on the parallel velocity gradient driven instability (PVG) in the presence of density inhomogeneity is theoretically investigated. The dispersion relation of PVG mode with the effect of density gradient and neutral particle drag is derived, and its solution is analytically obtained. The neutral particle drag gives rise to the phase shift between parallel flow and electrostatic potential fluctuations, and modifies the parallel compression. As a result, the stability of the PVG mode changes. It is found that the neutral particle drag does not only reduces but also enhances the instability. Especially, near the marginal condition, the neutral particle effect suppresses the density gradient effect, and the parameter region where the PVG mode is linearly unstable significantly expands.

show abstract

Section: Stability Of Pvg Including Neutral Particle Dragmentioning

confidence: 89%

Neutral particle drag on parallel flow shear driven instability

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

Impact of the electron density and temperature gradient on drift-wave turbulence in the Large Plasma Device

Perks

Mordijck²,

Carter³

et al. 2022

J. Plasma Phys.

View full text Add to dashboard Cite

In this paper we present an experimental study of edge turbulence in the Large Plasma Device at UCLA. We utilize a scan of discharge power and prefill pressure (neutral density) to show experimentally that turbulent density fluctuations decrease with decreasing density gradient, as predicted for resistive drift-wave turbulence (RDWT). As expected for RDWT, we observe that the cross-phase between the density and potential fluctuations is close to 0. Moreover, the addition of an electron temperature gradient leads to a reduction in the amplitude of the density fluctuations, as expected for RDWT. However, counter to theoretical expectations, we find that the potential fluctuations do not follow the same trends as the density fluctuations for changes either in density gradients or the addition of a temperature gradient. The disconnect between the density and potential fluctuations is connected to changes in the parallel flows as a result of differences in the prefill pressure, i.e. neutral density. Further analysis of the density and potential fluctuation spectra show that the electron temperature gradient reduces the low frequency fluctuations up to $10 \,{\rm kHz}$ and the introduction of a temperature gradient leads to an unexpected ${\sim }{\rm \pi}$ shift of the density–potential cross-phase at ${\sim }10\,{\rm kHz}$ , while maintaining the typical resistive drift-wave cross-phase at lower frequencies. These experiments partly confirm existing knowledge on resistive drift-wave turbulence, but also introduce new observations that indicate a need for dedicated nonlinear three-dimensional turbulence simulations that include neutrals.

show abstract

Transition between continuous and discrete spectra of high-wavenumber turbulence in neutral gas pressure scan experiments on a linear magnetized plasma

Kawachi,

Sasaki,

Nishizawa

et al. 2023

Plasma Phys. Control. Fusion

Self Cite

View full text Add to dashboard Cite

Spectral transition between continuous and discrete spectra has been observed in high-wavenumber turbulence excitation experiments. The transition appeared in neutral gas scanning, which shows that continuous spectra dominate at low gas pressures and discrete spectra dominate at high gas pressures. Both spectra have well smaller spatial scale than the ion effective Larmor radius. The discrete spectra have 6-11 peaks and maximum peak values at 4th or 5th peak. Correlation length analysis reveals that the continuous component is turbulent and the discrete component is coherent. The bicoherence analysis shows that the turbulent spectra have finite nonlinear coupling, whereas the discrete spectra have no corresponding coupling.

show abstract

Impact of helium neutral gas puff on plasma turbulence in linear magnetized argon plasmas

Cited by 4 publications

References 38 publications

Neutral particle drag on parallel flow shear driven instability

Neutral particle drag on parallel flow shear driven instability

Impact of the electron density and temperature gradient on drift-wave turbulence in the Large Plasma Device

Transition between continuous and discrete spectra of high-wavenumber turbulence in neutral gas pressure scan experiments on a linear magnetized plasma

Contact Info

Product

Resources

About