Investigation of recombination front region in detached plasmas in a linear divertor plasma simulator

Ohno, Noriyasu; Seki, Mayuko; Ohshima, Hiroshi; Tanaka, Hirohiko; Kajita, Shin; Hayashi, Y.; Natsume, Hiroki; Takano, Hiroki; Yoshikawa, M.; Meiden, H.J. van der

doi:10.1016/j.nme.2019.03.010

Cited by 25 publications

(30 citation statements)

References 10 publications

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“…Stronger oscillations in the ionization zone and/or recombination front region were observed in hydrogen plasmas in Pilot-PSI in earlier studies of linear divertor plasmas [6,7]. In an area that was axially localized and where pure He plasmas in NAGDIS-II experienced high volume recombination, the cross-field transport was enhanced [9][10][11]. The cross-field transport appeared to be enhanced in the region between the TS axial location and the target plate (Z tgt = 200 mm) at 1.4 Pa gas pressure [15].…”

Section: Introductionmentioning

confidence: 85%

“…At Z tgt = 150 mm, the reflectometry was used to measure the radial positions of approximately r ∼ 0.01 m. The reflectometry, photodiode, and high-speed camera all recorded peak fluctuation frequencies of about 3.4 kHz. By assuming T e = T i [9,10], the plasma potential could be derived using: V p ∼ V f + 3.7T e and the radial electric field strength (E r = −dV p /dr) was determined. The radial profile of the electric field strength E r at Z tgt = 150 mm is shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The radiation zone, ionization region, recombination region, and momentum loss region are thought to make up the plasma conditions along the magnetic field to the diverter plate [1][2][3][4]. In addition, in some linear plasma simulators, including NAGDIS-II, Pilot-PSI, and Magnum-PSI [5][6][7][8][9][10][11][12][13][14][15], and the SOL of the tokamak plasma of ASDEX Upgrade [16], low-frequency fluctuations around the recombination front region have been observed in the detached plasma conditions. These fluctuations result in radial particle losses across the magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Effects from the Target Plate Geometry on Fluctuations of Helium Plasma in the Linear Divertor Simulator Magnum-PSI

Yoshikawa

Tanaka

Hayashi

et al. 2022

Plasma and Fusion Research

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With the help of the linear divertor simulation device Magnum-PSI, a fluctuation investigation of the impact of the target plate geometry was conducted. We simultaneously quantify coherent low-frequency fluctuations with a newly built 70-GHz microwave reflectometry system, a reciprocating probe, a light emission detector system, and a fast-framing camera system. The strong low-frequency fluctuations were observed at both the electron density and the plasma radiations by moving the target plate along the magnetic field line. Furthermore, a strong peak in fluctuation intensity and the influence of the target plate tilt angle on the fluctuation intensity were noted. c

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Section: Introductionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects from the Target Plate Geometry on Fluctuations of Helium Plasma in the Linear Divertor Simulator Magnum-PSI

Yoshikawa

Tanaka

Hayashi

et al. 2022

Plasma and Fusion Research

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“…The effects of magnetic field strength (MFS) and the distance between the poles for argon discharge current (DC) electrical discharges on the Paschen's curves are studied for magnetic field strengths (0, 400, 855) Gauss and distances (2,4,6,8)cm (Khalaf, 2016). (Ohno, 2019), have made a detailed description of discharge structure around the recombination front region (RFR).In the present work, investigation and characterization of argon glow discharge plasma exerted by axial magnetic is concerned. The principle aim is to explain the variation of plasma parameters due to the application of external axial magnetic field, and eventually gas pressure.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Some Argon Plasma Parameters Glow Discharge Under Axial Magnetic Field

Karim

Mayi

Al-Hakary

2019

SJUOZ

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This paper investigates the characteristics some of argon plasma parameters of glow discharge under axial magnetic field. The DC power supply of range (0-6000) V is used as a breakdown voltage to obtain the discharge of argon gas. The discharge voltagecurrent (V-I) characteristic curves and Paschen's curves as well as the electrical conductivity were studied with the presents of magnetic field confinement at different gas pressures. The magnetic field up to 25 mT was obtained using four coils of radius 6 cm and 320 turn by passing A.C current up to 5 Amperes. Spectroscopic measurements are employed for purpose of estimating two main plasma parameters electron temperature (Te) and electron density (ne). Emission spectra from positive column (PC) zone of the discharge have been studies at different values of magnetic field and pressures at constant discharge currents of 1.5 mA. Electron temperature (Te) and its density are calculated from the ratio of the intensity of two emission lines of the same lower energy levels. Experimental results show the abnormal glow region characteristics (positive resistance). Breakdown voltage versus pressure curves near the curves of paschen and decrease as magnetic field increases due to magnetic field confinement of plasma charged particles. Also the electrical conductivity increases due to enhancing magnetic field at different gas pressures. Both temperature density of electron and the intensities of two selected emission lines decrease with increasing pressure due decreasing of mean free path of electron. Electron density increase according to enhancing magnetic field, while the intensity of emitting lines tends to decrease.

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“…In the detached divertor condition, an enhancement of the cross-field plasma transport is observed in several magnetic confinement devices including torus [1,2,3,4,5] and linear plasma devices [6,7,8,9,10,11]. In linear device NAGDIS-II, the enhanced transport was found to be generated locally along the magnetic field lines [12,9], and the region was identified to be near the highly volume-recombining region, called the "recombination front" [13]. Enhanced radial transport around the recombination front was also observed in the Magnum-PSI linear device, where gas pressure was varied to change the divertor condition between attached and detached states [11].…”

Section: Introductionmentioning

confidence: 99%

Study of the intermittent plasma structure around the divertor simulation experimental module in GAMMA 10/PDX

et al. 2023

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We have investigated the generation region of intermittent plasma structures, which could be due to the blob-like cross field transport around the divertor simulation experimental module (D-module) in the tandem mirror device GAMMA 10/PDX. A positive skewness of the ion saturation current was clearly seen when the electrode of the movable probe was located at the radial edge and just in front of the entrance limiter of the D-module. Fourier analysis and conditional averaging clarified that positive spikes intermittently appeared in the same region. This is the first indication that the phenomenon producing the high-density isolated plasma structures occurred in the upstream of the D-module. A negative skewness was also found, and large amplitude fluctuation was detected between regions showing positive and negative skewness. Furthermore, this and light emission fluctuations become stronger during the transient state from attached to detached state on the V-shaped target.

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Investigation of recombination front region in detached plasmas in a linear divertor plasma simulator

Cited by 25 publications

References 10 publications

Effects from the Target Plate Geometry on Fluctuations of Helium Plasma in the Linear Divertor Simulator Magnum-PSI

Effects from the Target Plate Geometry on Fluctuations of Helium Plasma in the Linear Divertor Simulator Magnum-PSI

Measurement of Some Argon Plasma Parameters Glow Discharge Under Axial Magnetic Field

Study of the intermittent plasma structure around the divertor simulation experimental module in GAMMA 10/PDX

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