Experimental study in the edge plasma of the HL-1 tokamak with a Mach probe and a directional probe

Zhang, J.; Shang, Z.Y.; Wang, E.Y.; Wang, Z.H.; Ran, Lingbing; Yang, H.R.; Huang, K.Q.; Liu, X.M.; Shangjie, Qian

doi:10.1016/0022-3115(94)00572-9

Cited by 4 publications

(2 citation statements)

References 10 publications

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“…The directional probe usually consists of two collectors located on the two sides of a central insulator. Directional probe has been applied on the measurements of parallel ion flow and floating potential in the magnetically controlled plasmas [29][30][31][32][33][34][35]. Herein we propose a new type of directional probe which has the capability to measure parallel electron current, and consequently this new probe is named directional electron probe (DEP).…”

Section: Introductionmentioning

confidence: 99%

Modelling and application of a new method to measure the non-thermal electron current in the edge of magnetically confined plasma

Liu¹,

Liang²,

Zhang³

et al. 2021

Nucl. Fusion

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The non-thermal electrons could form considerable current in the edge plasma of tokamak and stellarator. A new method, named directional electron probe (DEP), is proposed to measure the edge non-thermal electron current in magnetically confined plasma. The DEP consists of two opposite channels whose connection line aligns with the local magnetic field line. Each channel has a hole with small radial width and enough thickness to block high energy ions due to their large Larmor radii, and at the end of the hole the collector is biased to positive voltage to repel low energy ions. In this way, the collected current of DEP is mainly contributed by electrons. A particle orbit simulation is performed based on the Boris algorithm, which demonstrates the validity and rationality of the DEP. According to the simulation, the ion collection probability is quite small if compared with the electron collection probability, consequently the collected current is mainly contributed by electrons. The collected currents of thermal electrons under Maxwell–Boltzmann distribution from both channels are almost equal, and the net current is driven by non-thermal electrons. A radial array of DEP has been successfully applied to the scrape-off layer (SOL) non-thermal electron current measurement in EAST. The amplitude and structure of the non-thermal electron current are observed during the lower hybrid wave heating phase. The experimental SOL net current is compared with the simulated net current from a rough estimation, revealing the same radial structure of SOL current and demonstrating the validity of DEP.

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Section: Introductionmentioning

confidence: 99%

Modelling and application of a new method to measure the non-thermal electron current in the edge of magnetically confined plasma

Liu¹,

Liang²,

Zhang³

et al. 2021

Nucl. Fusion

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show abstract

“…Flow measurements in the edge and scrape-off layer (SOL) are important to understand the edge physics in fusion devices, to control impurities and in advanced confinement. To measure the plasma flow, a Mach probe has been used in various fusion devices such as Tore Supra [1], DIII-D [2] , ASDEX-U [3], Alcator C-Mod [4], HL-1 [5], CDX-U [6] and CASTOR [7]. A typical Mach probe is composed of two directional electric probes located on opposite sides of an insulator.…”

Section: Introductionmentioning

confidence: 99%

Effect of ion–neutral collision on the deduction of Mach number in collisional plasmas

Choi

Chung

Woo

et al. 2009

J. Phys. D: Appl. Phys.

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A new unmagnetized collisional Mach probe theory is developed in order to resolve the collisional effect on Mach probe analysis by including ionization, charge and momentum transfer of ions in the perturbation region of a Mach probe. A fluid model is established by assuming Boltzmann electrons and taking the moments of the one-dimensional Boltzmann transport equation, which contains the two-dimensional transport information as a source, after adding a collisional term. A new relation between the flow velocity and the ratio of the ion sheath current densities is obtained, and is compared with those by a collisionless kinetic theory and a particle-in-cell simulation in the applicable range of these theories. A new relation between flow velocity and the ratio of the ion sheath current densities shows that ion–neutral collisions have a very strong effect to produce much smaller Mach numbers from the same ratio than those by collisionless models.

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

Park

Woo

Chung

et al. 2012

Current Applied Physics

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Experimental study in the edge plasma of the HL-1 tokamak with a Mach probe and a directional probe

Cited by 4 publications

References 10 publications

Modelling and application of a new method to measure the non-thermal electron current in the edge of magnetically confined plasma

Modelling and application of a new method to measure the non-thermal electron current in the edge of magnetically confined plasma

Effect of ion–neutral collision on the deduction of Mach number in collisional plasmas

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

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