Effect of neutral pressure on the He plasma flow measurement in a linear device

Park, E.-K.; Woo, Hyun-Jong; Chung, Kyu‐Sun; Tanaka, Hirohiko; Kajita, Shin; Ohno, Noriyasu

doi:10.1016/j.cap.2012.04.024

Cited by 11 publications

(10 citation statements)

References 23 publications

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“…About 50000 particles were traced until almost all the particles disappeared, and the density profiles were obtained by accumulating the positions of particles until they disappeared. There exists a plasma flow from the upstream to downstream at least for ions in NAGDIS-II as was measured previously [28]. The range of the Mach number was 0.1-0.6 in the central region; when increasing the gas pressure, the flow decreased and the flow reversal occurred in the peripheral region.…”

Section: B Modelingsupporting

confidence: 63%

Behavior of 23S metastable state He atoms in low-temperature recombining plasmas

et al. 2017

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We measured the electron density and temperature using laser Thomson scattering and metastable state (2 3 S) of He atoms using laser absorption spectroscopy in the detached recombining plasmas in the divertor simulator NAGDIS-II. Using the measured electron density and temperature combined with the particle trajectory trace simulation, we discussed the behavior of the metastable state He atoms based on comparisons with the experimental results. It is shown that the metastable states atoms are mainly produced at the peripheral region of the plasma column, where the temperature is lower than the central part, and diffused in the vacuum vessel. It was shown that the 0D model is not valid and the transport of the metastable states is to be taken into account for the population distribution of He atoms valid in the detached plasmas.

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Section: B Modelingsupporting

confidence: 63%

Behavior of 23S metastable state He atoms in low-temperature recombining plasmas

et al. 2017

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“…19 In addition, plasma flow was also measured by varying the neutral gas pressure, P, in a range of 2-35 mTorr in NAGDIS-II. 20 The flow reversal in the axial direction was observed in the edge region when the neutral pressure was high (35 mTorr). The mechanism of reverse plasma flow is not fully understood yet.…”

Section: Introductionmentioning

confidence: 99%

Plasma flow in peripheral region of detached plasma in linear plasma device

et al. 2016

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A plasma flow structure is investigated using a Mach probe under detached plasma condition in a linear plasma device NAGDIS-II. A reverse flow along the magnetic field is observed in a steadystate at far-peripheral region of the plasma column in the upstream side from the recombination front. These experimental results indicate that plasma near the recombination front should strongly diffuse across the magnetic field, and it should be transported along the magnetic field in the reverse flow direction. Furthermore, bursty plasma density fluctuations associated with intermittent convective plasma transport are observed in the far-peripheral region of the plasma column in both upstream and downstream sides from the recombination front. Such a nondiffusive transport can contribute to the intermittent reverse plasma flow, and the experimental results indicate that intermittent transports are frequently produced near the recombination front. V

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“…The calibration factor does not seem to be a constant parameter at 40 <

< 130 and highly dependent on the collision parameters. In addition, the calculated calibration factor for collisional plasma conditions is much higher than that for collisionless models [ 15 ], which have similar results for the overestimation of plasma flow velocity in collisional plasmas by an MP [ 23 , 24 ].…”

Section: Resultsmentioning

confidence: 84%

“…Using the 2D simulation results of

at the center of the z-axis with pressure variation, as shown in Figure 6 , the calibration factor was calculated using Equation (10) as

. Figure 7 shows the results for the relation between the calibration factor and normalized ionization collision frequency (

) as a dimensionless parameter to deduce the effect of the collision parameter on the calibration factor, where

and

are the ionization collision frequency and the probe radius [ 15 , 23 , 24 ]. The calibration factor does not seem to be a constant parameter at 40 <

< 130 and highly dependent on the collision parameters.…”

Section: Resultsmentioning

confidence: 99%

“…The calibration factors for collisionless conditions have been studied using various kinetic and fluid models [ 19 , 20 , 21 ]. However, the overestimation of plasma flow velocity in collisional plasmas measured by an MP has been reported because of the effect of ion-neutral collision [ 22 , 23 , 24 ]. In collisional plasma, the overall flow behavior can be described by the conventional gas dynamic theory, because the major constituent of the plasma is still neutral atoms due to the low degree of ionization in typical plasma sources in collisional conditions [ 25 , 26 ].…”

Section: Measurement Of Plasma Flowmentioning

confidence: 99%

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Characteristics of Plasma Flow for Microwave Plasma Assisted Aerosol Deposition

et al. 2021

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To validate the possibility of the developed microwave plasma source with a novel structure for plasma aerosol deposition, the characteristics of the plasma flow velocity generated from the microwave plasma source were investigated by a Mach probe with pressure variation. Simulation with the turbulent model was introduced to deduce calibration factor of the Mach probe and to compare experimental measurements for analyses of collisional plasma conditions. The results show calibration factor does not seem to be a constant parameter and highly dependent on the collision parameter. The measured plasma flow velocity, which witnessed fluctuations produced by a shock flow, was between 400 and 700 m/s. The optimized conditions for microwave plasma assisted aerosol deposition were derived by the results obtained from analyses of the parameters of microwave plasma jet. Under the optimized conditions, Y2O3 coatings deposited on an aluminum substrate were investigated using scanning electron microscope. The results presented in this study show the microwave plasma assisted aerosol deposition with the developed microwave plasma source is highly feasible for thick films with >50 μm.

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Effect of neutral pressure on the He plasma flow measurement in a linear device

Cited by 11 publications

References 23 publications

Behavior of 23S metastable state He atoms in low-temperature recombining plasmas

Behavior of 23S metastable state He atoms in low-temperature recombining plasmas

Plasma flow in peripheral region of detached plasma in linear plasma device

Characteristics of Plasma Flow for Microwave Plasma Assisted Aerosol Deposition

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