scholarly journals Variation of Velocity of Ions in a Magnetized Plasma Sheath for Different Magnetic Field

2020 ◽  
Vol 6 (1) ◽  
pp. 25-29
Author(s):  
B.R. Adhikari ◽  
S. Basnet ◽  
H.P. Lamichhane ◽  
R. Khanal
Keyword(s):  
Magnetic Field ◽  
Space Charge ◽  
Space Charge Region ◽  
Normal Component ◽  
Maximum Amplitude ◽  
Plasma Sheath ◽  
Magnetized Plasma ◽  
Positive Space Charge ◽  
The Magnetic Field ◽  
Positive Space

The kinetic trajectory simulation method has been used to study ion velocity profile in a plasma sheath for varying magnetic field at fixed obliqueness. As the electrons have higher velocity compared to that of ions the wall is charged up negatively with respect to the core plasma. The negative potential then attracts the ions and repels electrons forming a thin positive space charge region in front of the wall. This positive space charge region, known as the ‘sheath’ separates the negatively charged wall from the quasineutral ‘presheath’ plasma. The ions moving towards the wall have to satisfy the Bohm criterion to ensure the stability of the overall plasma. The mean value as well as oscillation frequency of velocity of ions change as the magnetic field is varied from 1.5 to 10.5 mT. The maximum amplitude of normal component of velocity is almost independent of the magnetic field but the maximum amplitude of other components of velocity change and shows oscillating nature as the magnetic field changes.

scholarly journals Modulation frequency and velocity variation of ions in a magnetized plasma sheath for different obliqueness of the field

BIBECHANA ◽  
2021 ◽  
Vol 18 (1) ◽  
pp. 134-139
Author(s):  
Bhesha Raj Adhikari ◽  
Hari Prasad Lamichhane ◽  
Raju Khanal
Keyword(s):  
Magnetic Field ◽  
Modulation Frequency ◽  
Maximum Amplitude ◽  
Plasma Sheath ◽  
Magnetized Plasma ◽  
Velocity Variation ◽  
Damping Factor ◽  
Force Equation ◽  
The Given ◽  
The Magnetic Field

The understanding of ion dynamics in magnetized plasma sheath is crucial for all applications of plasma. The velocity variation as well as modulation frequency of ions in a magnetized plasma sheath has been studied for different obliqueness of the magnetic field. The governing Lorentz force equation has been solved numerically for the given boundary conditions as applicable in the kinetic simulation of the sheath. For different obliqueness of the magnetic field, the average values, maximum amplitude, damping factor as well as frequency of oscillation are studied. The oscillating velocity components change at different rates depending on their orientation with respect to the field direction. Significant changes in the damping factor and modulation frequency has been observed for all components of velocity; however, the frequency of oscillation remains the same. As the obliqueness increases, shoulder natures in the components of velocity are observed. BIBECHANA 18 (2021) 134-139

Thermally Stimulated Currents in the Range of Unity Gain Factor

1971 ◽  
Vol 26 (5) ◽  
pp. 819-823
Author(s):  
J. A. Bragagnolo ◽  
G. Dussel ◽  
K. W. Böer ◽  
G. A. Dussel
Keyword(s):  
Space Charge ◽  
Space Charge Region ◽  
Thermal Quenching ◽  
Gain Factor ◽  
Thermally Stimulated Current ◽  
Thermally Stimulated Currents ◽  
Positive Space Charge ◽  
Unity Gain ◽  
Positive Space

Abstract Thermally stimulated current-curves in CdS platelets with slit electrodes change their character when the photoelectric gain-factor increases above one. Here the photocurrent remains essentially frozen-in up to temperatures at which marked thermal quenching sets in. A positive space charge region is assumed to be responsible for the frozen-in photocurrent. A reliable TSC-analysis of the trap distribution can be conducted only for gain factors considerably below one.

scholarly journals BEAT FREQUENCY AND VELOCITY VARIATION OF IONS IN A MAGNETIZED PLASMA SHEATH FOR DIFFERENT OBLIQUENESS OF THE MAGNETIC FIELD

2019 ◽  
Vol 23 (1) ◽  
pp. 88-92
Author(s):  
B. R. Adhikari ◽  
S. Basnet ◽  
H. P. Lamichhane ◽  
R. Khanal
Keyword(s):  
Magnetic Field ◽  
Beat Frequency ◽  
Maximum Amplitude ◽  
Mean Value ◽  
Plasma Sheath ◽  
Magnetized Plasma ◽  
Velocity Variation ◽  
Constant Frequency ◽  
Mean Values ◽  
The Mean

 Beat frequency and velocity variation of ions in a magnetized plasma sheath has been numerically investigated by using a kinetic trajectory simulation (KTS) model for varying obliqueness of the external magnetic field in presence of an electric field. Angular dependence of mean value, maximum amplitude, damping constant, frequency of oscillation and beat frequency have been studied. As the obliqueness of the field changes the mean values, beat frequency as well as the maximum amplitude of the velocity components also change but frequency of oscillation remains almost the same.

scholarly journals Variation of velocity component of ions in a magnetized plasma sheath for different obliqueness of the magnetic field

2019 ◽  
Vol 8 ◽  
pp. 71-78
Author(s):  
Bhesha Raj Adhikari ◽  
Suresh Basnet ◽  
Hari Prasad Lamichhane ◽  
Raju Khanal
Keyword(s):  
Magnetic Field ◽  
Velocity Component ◽  
Full Text ◽  
Plasma Sheath ◽  
Magnetized Plasma ◽  
The Magnetic Field

available with full text.

scholarly journals FLUID ANALYSIS OF MAGNETIZED PLASMA SHEATH IN A CYLINDRICAL GEOMETRY

2018 ◽  
Vol 23 (1) ◽  
pp. 26-29
Author(s):  
P. K. Thakur ◽  
R. R. Pokhrel ◽  
R. Khanal
Keyword(s):  
Magnetic Field ◽  
Initial Conditions ◽  
Fluid Model ◽  
Plasma Jets ◽  
Plasma Sheath ◽  
Magnetized Plasma ◽  
Light Sources ◽  
Plasma Properties ◽  
Ion Density ◽  
The Magnetic Field

 Plasma sheath formed in front of a material wall plays an important role in overall plasma properties. Magnetized plasma sheath for both collisional and collisionless cases in a cylindrical co-ordinate system was studied using a fluid model. The fluid equations were compiled for the considered geometry and were solved numerically, using the fourth-order Runge-Kutta method for prescribed boundary and initial conditions. The ion velocity along the axis of the cylinder and the ion density profiles were studied for collisionless and collisional cases and at different obliqueness of the magnetic field. The ion velocities acquired its maximum value at the wall with monotonic increment in collisionless cases, whereas the ion density profile was not monotonic in collisionless case as well as when the obliqueness of the magnetic field starts increasing. In such cases, the ion density increases close to the entrance and then decreases monotonically towards the wall. The study provides insight to plasma properties in cylindrical plasmas which are common in discharge tubes, light sources and plasma jets.

The structure of the impulse corona in a rod/plane gap I. The positive corona

1970 ◽  
Vol 315 (1520) ◽  
pp. 1-25 ◽  
Keyword(s):  
Spatial Distribution ◽  
Electric Field ◽  
Space Charge ◽  
Negative Ions ◽  
Corona Discharges ◽  
Theoretical Derivation ◽  
Plane Electrode ◽  
Positive Space Charge ◽  
Positive Ion ◽  
Positive Space

The dissipation of space charge following the growth of impulse corona discharges in positive rod/earthed plane gaps has been measured with an electrostatic fluxmeter. A method is described to determine the spatial distribution and magnitude of the space charge together with the associated electric field. Initial positive ion densities of up to 100 μC m -3 have been found. The total positive space charge deposited in a 40 cm gap at 160 kV is 500 nC. Electrons emitted from the plane electrode as a result of corona channels crossing the gap are shown to be trapped in the discharge space as negative ions. The recovery of the gap over several seconds is largely due to ionic drift to the electrodes. A theoretical derivation of the rate of deionization agrees with observed values.

scholarly journals Lepton-driven Nonresonant Streaming Instability

2021 ◽  
Vol 923 (2) ◽  
pp. 208
Author(s):  
Siddhartha Gupta ◽  
Damiano Caprioli ◽  
Colby C. Haggerty
Keyword(s):  
Magnetic Field ◽  
Laboratory Experiments ◽  
Magnetized Plasma ◽  
Ion Current ◽  
Pulsar Wind Nebulae ◽  
Particle In Cell ◽  
Streaming Instability ◽  
Electrons And Positrons ◽  
Pulsar Wind ◽  
The Magnetic Field

Abstract A strong super-Alfvénic drift of energetic particles (or cosmic rays) in a magnetized plasma can amplify the magnetic field significantly through nonresonant streaming instability (NRSI). While the traditional analysis is done for an ion current, here we use kinetic particle-in-cell simulations to study how the NRSI behaves when it is driven by electrons or by a mixture of electrons and positrons. In particular, we characterize the growth rate, spectrum, and helicity of the unstable modes, as well the level of the magnetic field at saturation. Our results are potentially relevant for several space/astrophysical environments (e.g., electron strahl in the solar wind, at oblique nonrelativistic shocks, around pulsar wind nebulae), and also in laboratory experiments.

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