Correlation between the plasma parameters and the extracted current density in the volume-production based sources of negative hydrogen ions

2012 ◽  
Vol 83 (2) ◽  
pp. 02A709 ◽  
Author(s):  
St. Lishev ◽  
A. Shivarova ◽  
Kh. Tarnev
Keyword(s):  
Current Density ◽  
Hydrogen Ions ◽  
Plasma Parameters ◽  
Volume Production

scholarly journals On the deviation from Maxwellian of the ion velocity distribution functions in the turbulent magnetosheath

2020 ◽  
Vol 86 (1) ◽  
Author(s):  
S. Perri ◽  
D. Perrone ◽  
E. Yordanova ◽  
L. Sorriso-Valvo ◽  
W. R. Paterson ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Electric Fields ◽  
Current Density ◽  
Distribution Functions ◽  
Poor Correlation ◽  
Ion Temperature ◽  
Plasma Parameters ◽  
Density Peaks ◽  
Velocity Distribution Functions ◽  
Ion Velocity

The deviation from thermodynamic equilibrium of the ion velocity distribution functions (VDFs), as measured by the Magnetospheric Multiscale (MMS) mission in the Earth’s turbulent magnetosheath, is quantitatively investigated. Making use of the unprecedented high-resolution MMS ion data, and together with Vlasov–Maxwell simulations, this analysis aims at investigating the relationship between deviation from Maxwellian equilibrium and typical plasma parameters. Correlations of the non-Maxwellian features with plasma quantities such as electric fields, ion temperature, current density and ion vorticity are found to be similar in magnetosheath data and numerical experiments, with a poor correlation between distortions of ion VDFs and current density, evidence that questions the occurrence of VDF departure from Maxwellian at the current density peaks. Moreover, strong correlation has been observed with the magnitude of the electric field in the turbulent magnetosheath, while a certain degree of correlation has been found in the numerical simulations and during a magnetopause crossing by MMS. This work could help shed light on the influence of electrostatic waves on the distortion of the ion VDFs in space turbulent plasmas.

scholarly journals Inertial Effects on Tearing Instability

2016 ◽  
Vol 3 (3) ◽  
pp. 155-157
Author(s):  
F. E. M. Silveira
Keyword(s):  
Relaxation Time ◽  
Current Density ◽  
Wave Length ◽  
Standard Theory ◽  
Inertial Effects ◽  
Plasma Parameters ◽  
Long Wavelength ◽  
Tearing Modes ◽  
Wavelength Limit ◽  
Tearing Instability

In this work, we explore inertial effects, due to charged species in a resistive plasma, on the tearing instability. The standard theory of tearing modes assumes a long wavelength limit. At shorter wave lengths, inertial effects can become important and the current density flowing in the fluid can acquire a finite relaxation time. The introduction of such a correction into the problem leads to an extension of the standard dispersion relation. In the long wave length limit, we recover the standard scaling of the growth rate γ with the plasma resistivity η, namely γ ≈ η3/5. However, in the short wavelength limit, we find that the scaling of γ with the relevant plasma parameters changes significantly due to the influence of inertia. Notwithstanding, the dependence of γ on the relaxation time of the current density is not determined. In order to achieve such a description, we propose to further rediscuss the problem in the framework of the boundary layer technique.

scholarly journals ELECTROCATALYSIS OF THE HYDROGEN EVOLUTION REACTION ON CoRe, CoWRe SUPERALLOYS DEPOSITED FROM CITRATE ELECTROLYTE

2020 ◽  
Vol 86 (9) ◽  
pp. 28-38
Author(s):  
Yuliya Yapontseva ◽  
Tetiana Maltseva ◽  
Valeriy Kublanovsky
Keyword(s):  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
Current Density ◽  
Hydrogen Reduction ◽  
Ternary Alloys ◽  
Hydrogen Ions ◽  
Citrate Electrolyte ◽  
Order Of Magnitude ◽  
Rhenium Content ◽  
Deposition Current Density

The reaction of electroreduction of hydrogen ions on binary CoRe and ternary CoWRe alloys electrodeposited from a citrate electrolyte with different amount of potassium perrhenate (0.01 and 0.05 mol·L-1) depending on the deposition current density (5–40 A·cm-2) has been investigated by the method of stationary voltammetry. The kinetic parameters of the reaction have been calculated, and it is shown that the use of ternary alloys allows one to increase the value of exchange current density by almost an order of magnitude and significantly reduce the overvoltage of hydrogen reduction in comparison with cobalt. It is shown that the best electrocatalysts for the reduction of hydrogen in alkaline solution can be ternary CoWRe alloys with a rhenium content of 15–20 at. %.

scholarly journals Effect of Presheath Current Density on the Sheath Structure of Plasma

2012 ◽  
Vol 3 ◽  
pp. 10-12
Author(s):  
S. J. B. Gurung ◽  
R. Khanal
Keyword(s):  
Electron Density ◽  
Current Density ◽  
Electron Densities ◽  
Plasma Parameters ◽  
Ion Density ◽  
Sheath Region ◽  
Trajectory Simulation ◽  
Sheath Structure

A Kinetic Trajectory Simulation (KTS) model is used to study the effect of presheath current density on the sheath region. It has been observed that the plasma parameters in the sheath region and at the material wall are highly influenced by the presheath current density. Electron density at the wall is found to increase linearly and sharply, whereas ion density at the wall is found to be increasing nonlinearly and monotonically with respect to the presheath current density. Starting with the same density at the sheath entrance, i.e. 1018 m-3, the ion and electron densities at the wall change from 3.761 × 1017 m-3 to 4.436 × 1017 m-3 and 1.250 × 1016 m-3 to 5.156 × 1016 m-3 when the presheath current density increases from -3.507 × 103 Am-2 to 3.507 × 103 Am-2 respectively. The result obtained is expected to be useful in controlling the flow of particles at the wall.The Himalayan PhysicsVol. 3, No. 32012Page : 10-12

scholarly journals Current status of the compact 2.45 GHz ECR Ion Source at FLNR JINR

2019 ◽  
Vol 201 ◽  
pp. 08002
Author(s):  
Riyaz Fatkullin ◽  
Sergey Bogomolov ◽  
Andrey Efremov ◽  
Vladimir Loginov ◽  
Yuri Kostukhov ◽  
...  
Keyword(s):  
Current Density ◽  
High Frequency ◽  
Test Bench ◽  
Ion Source ◽  
Ion Sources ◽  
Current Status ◽  
Hydrogen Ions ◽  
Ecr Ion Source ◽  
Ultra High Frequency ◽  
Extraction Voltage

This paper describes recent results obtained with a compact 2.45 GHz ECR Ion Source at the ECR ion sources test bench. The source was tested for production of helium and hydrogen ions with different configurations of Ultra High Frequency (UHF) coupler, UHF power and frequency. At the extraction voltage about of 10 kV and UHF power about of 100 W more than 500 µA of He + ions were produced with the extraction hole of 3 mm in diameter that corresponds to the current density of 7.5mA/cm2. The future possible upgrades of the ion source are also discussed.

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