Effects of electrode gap on radio-frequency discharge characteristics with a hollow electrode

He, Lin; He, Feng; Ouyang, Jiting; Dou, Wenna

doi:10.1063/5.0022019

Cited by 11 publications

(7 citation statements)

References 49 publications

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“…the energy is transferred from ambient turbulence to GAM zonal flows. Similar experimental results have been reported in other devices, such as AUG, DIII-D, JFT-2M, HL-2A and TEXTOR [37][38][39][40][41][42]. On the other hand, figures 6(b) and (d) show that the stretch of the Lissajous cycle is stronger in D plasmas than that in H plasmas, reflecting stronger correlations between GAM zonal flows and ambient turbulence in D plasmas.…”

Section: Interaction Between Gam Zonal Flows and Turbulence In D And ...supporting

confidence: 87%

Isotope effects on turbulence and zonal flows in HL-2A edge plasmas

He¹,

Cheng²,

Xu³

et al. 2022

Nucl. Fusion

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The effect of isotope mass on the interaction between turbulence and geodesic acoustic mode (GAM) zonal flows has been investigated in HL-2A ohmically heated deuterium (D) and hydrogen (H) plasmas using a double-step Langmuir probe array. The experimental results indicate that the level of GAM zonal flows and the turbulence eddy size together with the eddy tilting angle are all increased in the edge region in D plasmas compared to those in H plasmas under similar discharge parameters involving plasma current, magnetic field and line-averaged density. Evidence shows that in D plasmas, the nonlinear energy transfer is the main cause of the stronger excitation of GAM zonal flows, which extract more energy from ambient turbulence and, consequently, lead to lower turbulent transport and better confinement in D plasmas. The experimental findings may contribute to the understanding of the isotopic physics and associated turbulent transport in tokamak plasmas.

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Section: Interaction Between Gam Zonal Flows and Turbulence In D And ...supporting

confidence: 87%

Isotope effects on turbulence and zonal flows in HL-2A edge plasmas

He¹,

Cheng²,

Xu³

et al. 2022

Nucl. Fusion

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“…The XOOPIC code is utilized in the simulation, which is an object-oriented 2d3v (two-dimensional coordinate space and three-dimensional velocity space) PIC-MCC code. [32][33][34][35] A detailed description of this model can be found in our previous work, [36] hence in this work the model is described only briefly . Electron and argon ion (Ar + ) are the main particles in the simulation.…”

Section: Description Of Modelmentioning

confidence: 99%

“…[27,41] It has been confirmed that both the sheath oscillation heating and secondary electron heating are important in maintaining the discharges under the simulated conditions in this work. [36] In the following, the variation of the HCE in one RF period is analyzed in detail.…”

Section: Hce Variation Lawmentioning

confidence: 99%

Hollow cathode effect in radio frequency hollow electrode discharge in argon

He 贺,

He 何,

Ouyang 欧

2024

Chinese Phys. B

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Radio frequency capacitively coupled plasma sources (RF-CCPs) with hollow electrodes can increase the electron density through the hollow cathode effect (HCE), which offers a method to modify the spatial profiles of the plasma density. In this paper, the variations of the HCE within one RF period were investigated by a two-dimensional particle-in-cell/Monte-Carlo collision (PIC/MCC) model. The results show that the sheath electric field, the sheath potential drop, the sheath thickness, the radial plasma bulk width, the EEDF, and the average electron energy in the cavity vary within one RF period. During the hollow electrode sheaths expansion phase, the secondary electron heating and sheath oscillation heating in the cavity are gradually enhanced, and the frequency of the electron pendular motion in the cavity gradually increases, hence the HCE is gradually enhanced. However, during the hollow electrode sheaths collapse phase, the secondary electron heating is gradually attenuated. In addition, when interacting with the gradually collapsed hollow electrode sheaths, high-energy plasma bulk electrons in the cavity will lose some energy. Furthermore, the frequency of the electron pendular motion in the cavity gradually decreases. Therefore, during the hollow electrode sheaths collapse phase, the HCE is gradually attenuated.

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“…The 2D particle-in-cell/Monte Carlo collision (PIC-MCC) simulation of a hollow cathode slot [2] showed that the secondary electron acceleration within the sheath can play an important role. PIC-MCC simulation for HCDs at different electrode gaps [12] showed that a small electrode gap is not beneficial for obtaining large area plasma with high plasma density outside the hole.…”

Section: Introductionmentioning

confidence: 99%

A neural-network-based model of radio-frequency hollow cathode discharge characterized using particle-in-cell/Monte Carlo collision simulation

Bera,

Verma,

Ganta

et al. 2024

J. Phys. D: Appl. Phys.

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Understanding of plasma dynamics of radio-frequency (RF) hollow cathode discharges (HCD) at low to moderate pressures is important due to their wide range of applications. A hollow cathode discharge (HCD) consists of a hollow cylindrical cavity in the radio-frequency (RF) powered cathode separated from a grounded electrode by a dielectric. In RF HCDs, RF sheath heating can play a significant role in plasma production in addition to secondary electrons. In this study, a single hollow cathode hole is modeled using the Particle-in-Cell/Monte Carlo Collision (PIC-MCC) technique at low pressure where kinetic effects are important. Characterizing a single hollow cathode using PIC-MCC simulation is, however, computationally expensive. For improved computational efficiency, a neural network modeling framework has been developed using the temporal variations of applied RF voltages as input and electrode current as output. A space-filling design of computational experiments is used where the variables include the RF voltage at the fundamental frequency, RF voltage at the second harmonic, and their phase difference. The predictions of the electrode current using the trained neural network model compare well with the results of the PIC/MCC simulations but at a significantly lower computational cost. The neural network model predicts the current very well inside the training domain, and reasonably well even outside the training domain considered in this study.

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Effects of electrode gap on radio-frequency discharge characteristics with a hollow electrode

Cited by 11 publications

References 49 publications

Isotope effects on turbulence and zonal flows in HL-2A edge plasmas

Isotope effects on turbulence and zonal flows in HL-2A edge plasmas

Hollow cathode effect in radio frequency hollow electrode discharge in argon

A neural-network-based model of radio-frequency hollow cathode discharge characterized using particle-in-cell/Monte Carlo collision simulation

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