Control of the well-type radial potential profile in the magnetized plasma flow produced by a dc discharge

Matsubara, Atsushi; Tonegawa, Akira; Shibuya, Takehisa; Sato, K.; Kawamura, Kazutaka; Takayama, K.

doi:10.1063/1.1361239

Cited by 4 publications

(2 citation statements)

References 19 publications

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“…See, for example, the data presented in figure 2 of [2], or the schematic drawing in figure 2(b). Double sheaths can form in several circumstances including the presence of ion beams [3], applied magnetic fields [4], or as a result of non-local effects such as global balance of electron and ion currents lost from a plasma [2]. In this paper we report that double sheaths and anode spots can sometimes be present in combination as well.…”

Section: Introductionmentioning

confidence: 75%

Equilibrium states of anodic double layers

Baalrud

Longmier

Hershkowitz

2009

Plasma Sources Sci. Technol.

116

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Equilibrium states of anodic double layers that form near a positively biased disk-shaped electrode immersed in a partially ionized plasma are studied experimentally using electrostatic probes. When the potential drop from the electrode to the plasma is less than a critical value, φ c , an anode glow is observed where a double layer potential drop is within a few millimeters of the electrode surface. For larger biases an anode spot forms where the double layer potential drop is centimeters from the electrode and the intervening region is a plasma more luminous than the bulk plasma. A theoretical model is developed which predicts that φ c ∝ 1/P + C, where P is the neutral pressure and C is a constant, and it predicts hysteresis in the current-voltage characteristic at the electrode; both effects are observed experimentally. The model also provides an estimate for the distance between the electrode and double layer potential drop that agrees with the measurements. Near small electrodes, anode spots are observed to be 'fireballs,' which are spherical in shape. Near larger electrodes 'firerods' are found instead, which have a cylindrical shape. It is shown that firerods are required by global current balance because they have a smaller effective electron collecting area than fireballs. Experiments also confirm that global nonambipolar flow (Baalrud S D et al 2007 Phys. Plasmas 14 042109) accompanies firerods. In this case all electrons are lost through the firerod to the electrode, while all positive ions are lost to the other plasma boundaries.

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Section: Introductionmentioning

confidence: 75%

Equilibrium states of anodic double layers

Baalrud

Longmier

Hershkowitz

2009

Plasma Sources Sci. Technol.

116

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“…Generally, a well-type radial potential profile is formed in magnetized sheet or cylindrical plasmas generated by a dc arc discharge. 22 Since the electric field due to the potential well may force the negative ions to the peripheral region, it is necessary to investigate the transport effect by considering the effect of electric field.…”

Section: Introductionmentioning

confidence: 99%

Effect of cross-field transport on H− density profile in magnetized plasmas: Comparison between measurement and simulation

et al. 2007

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The radial density profile of negative hydrogen ions in magnetized plasma is investigated in the divertor simulator MAP (Material and plasma)-II [S. Kado et al., J. Plasma Fusion Res. 71, 810 (2005)] by measurement and numerical simulation. The laser photodetachment method is used to evaluate the H− density by considering the influence of the magnetic field. The density of H− has a hollow profile and exhibits a peak in the peripheral region, though the electron density and temperature exhibit a peak at the center of the plasma column. The density profile of H− does not agree with the calculation result obtained from the rate equation, in which the local production and extinction rates are balanced, under the present experimental condition. To understand the behavior of negative ions, their trajectories are calculated by numerically solving the equation of motion by considering the effect of collisions. The negative ion density profile calculated from the particle simulation agrees well with the measured negative ion density profile. It is shown that the cross-field H− transport due to the radial electric field with the assistance of the elastic collisions plays an important role in enhancing the negative ion density in the peripheral region.

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Radial control of plasma uniformity and electron temperature by external plate biasing in a back diffused partially magnetized plasma

Das¹,

Karkari²

2021

Plasma Res. Express

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Control of the well-type radial potential profile in the magnetized plasma flow produced by a dc discharge

Cited by 4 publications

References 19 publications

Equilibrium states of anodic double layers

Equilibrium states of anodic double layers

Effect of cross-field transport on H− density profile in magnetized plasmas: Comparison between measurement and simulation

Radial control of plasma uniformity and electron temperature by external plate biasing in a back diffused partially magnetized plasma

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