Raju Khanal

Self-consistent one dimension in space and three dimension in velocity kinetic trajectory simulation model of magnetized plasma-wall transition

We have developed a self-consistent 1d3v (one dimension in space and three dimension in velocity) Kinetic Trajectory Simulation (KTS) model, which can be used for modeling various situations of interest and yields results of high accuracy. Exact ion trajectories are followed, to calculate along them the ion distribution function, assuming an arbitrary injection ion distribution. The electrons, on the other hand, are assumed to have a cut-off Maxwellian velocity distribution at injection and their density distribution is obtained analytically. Starting from an initial guess, the potential profile is iterated towards the final time-independent self-consistent state. We have used it to study plasma sheath region formed in presence of an oblique magnetic field. Our results agree well with previous works from other models, and hence, we expect our 1d3v KTS model to provide a basis for the studying of all types of magnetized plasmas, yielding more accurate results.

Improvement of wettability and absorbancy of textile using atmospheric pressure dielectric barrier discharge

In this study, cotton textile samples, commonly used in making quilt covers were subjected to atmospheric pressure dielectric barrier discharge treatment to study their surface wettability and absorbancy. Samples were treated in the discharge using a rotatory mechanism and the effects of plasma treatment were examined by contact angle measurement and weight measurement. Air plasma treatment was successful in incorporating hydrophilic functional groups on the textile surface due to which wettability as well as absorbancy immediately after the treatment were highly improved. Effects of plasma treatment started to appear only after 20 cycles (9 mins) and got saturated after 24 cycles (10.8 mins) of treatment. The contact angle reduced from 137 ° (untreated sample) to a value less than 30 ° while absorbancy increased by more than two times as compared to untreated sample. Also, the aging behavior of the plasma treated samples were studied for about a week after plasma treatment. It was observed that the induc...

Response of carbon and tungsten surfaces to hydrogen plasma of different temperatures

The basic understanding of the interaction between energetic hydrogen plasma with carbon and tungsten based surfaces is crucially important for analyzing plasma-wall interaction in divertors of fusion devices and other plasma applications. The ion reflection coefficient, ion absorption coefficient, total ion charge density, and ion density distribution have been studied using a kinetic trajectory simulation model at different ion temperatures. It has been observed that the ion reflection coefficient and the ion absorption coefficient of the incident particles depend on kinetic energy: higher energy ions are less likely to be reflected as they have enough energy to bury themselves within the solid.

Measurement of Plasma Density in Brass Arc Plasma at Atmospheric Pressure Using a Langmuir Single Probe

In this work, we construct electrodes of brass to produce plasma by arc discharge and is characterized by using a movable Langmuir single probe. It is a simple way to measure plasma parameters such as electron temperature, electron density and ion density. A movable Langmuir single probe technique has a reference point since it is biased with reference to any one electrode of the plasma producing system. The values obtained are at atmospheric pressure. The plasma thus produced in laboratory has various applications which include gaseous discharge, plasma torch, sputtering, laser produced plasma as well as tokamak plasma.

Effects of collision and ion Mach number on magnetized plasma sheath with two species of positive ions

We study the effect of collision and ion Mach number in a magnetized plasma sheath having two species of positive ions using fluid model. It is assumed that both the ions are singly ionized and in thermal equilibrium, and the electrons obey Boltzmann distribution. Our work signifies that the collision greatly affects the ion densities, which explicitly affect space charge density, net current density and the transverse drift of ions. On increasing the collisional frequency, ions accumulation point and current saturation point shift towards the sheath entrance (away from the wall). The ion Mach number affects potential profile and velocity profiles of both ion species. The magnitude of wall potential increases from 34 V to 45 V with the increase in ion Mach number from 0.3 to 0.9. Furthermore, it is shown that the effect of collisional force and Lorentz force is reduced at the sheath entrance by increasing the ion Mach number, which helps to control the flux of particles, momentum flow and energy flow towards the wall.We study the effect of collision and ion Mach number in a magnetized plasma sheath having two species of positive ions using fluid model. It is assumed that both the ions are singly ionized and in thermal equilibrium, and the electrons obey Boltzmann distribution. Our work signifies that the collision greatly affects the ion densities, which explicitly affect space charge density, net current density and the transverse drift of ions. On increasing the collisional frequency, ions accumulation point and current saturation point shift towards the sheath entrance (away from the wall). The ion Mach number affects potential profile and velocity profiles of both ion species. The magnitude of wall potential increases from 34 V to 45 V with the increase in ion Mach number from 0.3 to 0.9. Furthermore, it is shown that the effect of collisional force and Lorentz force is reduced at the sheath entrance by increasing the ion Mach number, which helps to control the flux of particles, momentum flow and energy flow towa...

Effect of Ion Temperature Variation in Two-Ion Species Magnetized Plasma Sheath

For all practical applications of plasma, it has to be confined and in all such cases a sheath is formed at the material wall, which plays an important role in the properties of overall plasma wall transition region. The effect of ion temperature in a magnetized plasma sheath, which consists of two species of positive ions, has been studied using kinetic theory. The profile of ion densities, electron density, total charge density, potential is obtained by self-consistent solution to a non-neutral, collisionless, time independent plasma sheath. The physical parameters change slowly near the sheath entrance but exhibit steep gradient near the wall. The effect of applied magnetic field is more on ions whereas the electrons are almost non responsive and they are not influenced directly. In presence of magnetic field, the ion density is slightly lower compared to the case without magnetic field. The ion density increases on increasing ion temperature due to increase in their thermal velocity. On increasing the ion temperature, the total charge density at the wall increases and hence the potential decreases in magnitude. The result is useful in understanding and hence controlling the particles in plasma wall transition region especially in cases of two-ion species magnetized plasma sheath.