Plasma characteristics of a tapered coaxial gun and its damage effect on tungsten target

Zhao, Chongxiao; Qi, Liangwen; Ma, Chunyu; Hu, Jinjuan; Bai, Xiaodong; Wang, Dezhen

doi:10.1016/j.fusengdes.2020.111870

Cited by 5 publications

(6 citation statements)

References 25 publications

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“…This paper enumerates the parameters for density calculation. The specific method of Stark broadening calculation has been described in detail in other articles of the author [12,28]. The value obtained at this position is the largest density of plasma.…”

Section: Characteristics Of Plasmamentioning

confidence: 99%

“…In this paper, the Stark broadening method is used to calculate the electron density [9,12,23,[25][26][27][28]. The fitted line as shown in figure 6(a) can be obtained by fitting the H β line in figure 5.…”

Section: Characteristics Of Plasmamentioning

confidence: 99%

“…Previous studies have shown that the energy density and electron energy of the plasma ejected from the muzzle of a tapered coaxial gun are higher than those of a cylindrical gun because of the physical compression [13]. On the other hand, the plasmoid ejected from a tapered gun is relatively uniform and can maintain collimation [12].…”

Section: Introductionmentioning

confidence: 98%

“…With the development of ITER, the heat load of ELMs increases gradually, so it is necessary to use a higher parameter plasma source for simulation experiments. In order to get more suitable results for tokamak in the simulation experiments using a coaxial plasma gun, a tapered coaxial gun with negative pulse was used [12]. Previous studies have shown that the energy density and electron energy of the plasma ejected from the muzzle of a tapered coaxial gun are higher than those of a cylindrical gun because of the physical compression [13].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Experimental study on plasma generated by a tapered coaxial accelerator and its damage effects on a tungsten target at different angles

Zhao¹,

Chen²,

Song³

et al. 2022

Plasma Phys. Control. Fusion

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Plasma wall interaction (PWI) will occur inevitably during the operation of Tokamak. The coxial gun device has low operation cost and parameters of plasma produced by the gun are close to those of type I ELM, therefore, the coaxial gun is suitable in simulation experiment as heat-flux sources of transient events such as type I ELM under the condition of H-mode in ITER. In this paper, the plasma generated by the discharge of a tapered coaxial accelerator thermal shock on a tungsten target to simulate the damage effect of the divertor. The plasma parameters are measured in the experiment. The velocity of the plasma is 41.7 km/s, and the kinetic energy of a single hydrogen ion is 9.2 eV. The energy density at the center of the plasma can reach 1.5 MJ/m2, and the density can reach about 2.78×1015 /cm3. The reflection of plasma in the process of exposure at different angles is observed. It is observed that droplets of millimeter size splash from the target. Traces of liquid flow are observed on the surface of the target, which shows that there is a melting process on the surface of target. The mass loss of the target is in the order of mg after 20 pules. The ablation and residual stress of the target surface both decrease with the decrease of the angle. This is because the accumulated energy per unit area of the target surface decreases with the decrease of the angle. These results help us to better understand the damage effect of tungsten target for further research.

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Section: Characteristics Of Plasmamentioning

confidence: 99%

Section: Characteristics Of Plasmamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental study on plasma generated by a tapered coaxial accelerator and its damage effects on a tungsten target at different angles

Zhao¹,

Chen²,

Song³

et al. 2022

Plasma Phys. Control. Fusion

Self Cite

View full text Add to dashboard Cite

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“…Coaxial gun plasma sources have been extensively studied over the recent decades for a variety of applications. These include plasma refueling for fusion machines [1][2][3][4], as thrusters for space propulsion [5,6], simulations of astrophysical phenomena [7][8][9][10], acceleration of dust particles [11,12], type I edge localized mode (ELMs-I) simulation for ITER [13][14][15][16][17] and studies of magnetic field reconnection and instabilities in plasmas [18][19][20]. Based on this wide applicability, there is great interest in understanding the discharge characteristics of coaxial plasma guns and measuring the physical properties (density, ejection velocity, temperature, etc) of plasma.…”

Section: Introductionmentioning

confidence: 99%

Effects of bias magnetic field on plasma ejection and dynamic characteristics of a coaxial gun operated in gas-puffed mode

Qi¹,

Song²,

Zhao³

et al. 2021

Plasma Phys. Control. Fusion

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The effects of bias magnetic field on the discharge characteristics of a coaxial gun and the parameters of ejected plasma are studied. At constant initial conditions (charging voltage, gas-puffed), magnetic probe data at different axial positions reveal the influence of the external bias magnetic field on the current distribution within the annular flow channel. Both photodiode signals and plasma radiation images show the plasma ejection characteristics. It is found that either applying or not applying the bias magnetic field results in two types of plasma with distinct ejection characteristics: spheromak or jet. By comparing the plasma parameters with and without bias magnetic field, it is found that the variation of jets velocity and momentum with discharge conditions are consistent with the snowplow model, whereas the spheromak plasma is subjected to a retarding force −J ϕ B r ⇀ z during the ejection, which decelerates the spheromak. Irrespective of the bias magnetic field, an increase in the discharge current amplitude leads to an elevation in electron density and temperature. The density of the spheromak is lower than that of the jet, but the temperature is higher. This is due to the fact that the electromagnetic focusing mechanism in the jet leads to a further increase in density, while the magnetic field lines stretched during the formation of the spheromak inhibit the focusing effect and expand freely after ejection. In addition, the magnetic field stretching process consumes part of the axial kinetic energy from the plasma and converts it into magnetic energy. The subsequent magnetic reconnection event causes the magnetic energy to be dissipated resistively by heating the plasma and then be converted into thermal energy. These results give us a better understanding in the interaction between plasma and magnetic field.

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Development of a repetitive plasma source for simulation of mitigated edge localized mode transient heat load

Liu

Shi

et al. 2022

Review of Scientific Instruments

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A repetitive plasma source for simulation of mitigated edge localized mode transient heat load is developed. The repetitive plasma source consists of a repetitive pulsed power supply and a pulsed plasma accelerator. The pulsed plasma accelerator is composed of a coaxial cathode, an anode, and an insulator. The inner electrode is the cathode with a diameter of 5 mm, and the outer electrode is the anode with a diameter of 15 mm. An angular magnetic field is generated by the discharge current and acts with the radial current to generate Lorentz force, which drives the plasma ejecting to the outlet. The repetitive pulsed power supply can be divided into three parts, the primary charge circuit, the resonant charge circuit, and the discharge circuit. The time interval between resonant charge and discharge is 4 ms. The repetitive discharge components include ten modules running in parallel. There are four working modes for discharge components, depending on the number of simultaneously discharged modules. For Mode A, the maximum repetitive frequency is 50 Hz, and the transient heat load is 0.06 MJ/m2 when the discharge current is 10.5 kA. For Mode D, the maximum repetitive frequency is 5 Hz, and the transient heat load is 0.45 MJ/m2 when the discharge current is 66 kA. This is of great significance for the study of the interaction between plasma and plasma-facing materials in tokamak.

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Plasma characteristics of a tapered coaxial gun and its damage effect on tungsten target

Cited by 5 publications

References 25 publications

Experimental study on plasma generated by a tapered coaxial accelerator and its damage effects on a tungsten target at different angles

Experimental study on plasma generated by a tapered coaxial accelerator and its damage effects on a tungsten target at different angles

Effects of bias magnetic field on plasma ejection and dynamic characteristics of a coaxial gun operated in gas-puffed mode

Development of a repetitive plasma source for simulation of mitigated edge localized mode transient heat load

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