Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEffect of collisions on the plasma sheath in the presence of an inhomogeneous magnetic field
301
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
A low-pressure magnetized plasma is studied to find the dependency of sheath properties on ion-neutral collisions in presence of an inhomogeneous magnetic field. A self-consistent one-dimensional two-fluid hydrodynamic model is considered, and the system of equations is solved numerically. The study reveals that the width of the plasma sheath expands and space charge increases with collisions. The ion-neutral collisions and the inhomogeneous magnetic field restrict the ions to move towards the surface. The movement of the ions towards the wall can be controlled by choosing a suitable configuration of the magnetic field and ion-neutral collision frequency. A comparison between two different magnetic field configurations has been presented alongside to differentiate the commonly found scenarios in the field. The outcome of the study is supposed to help in understanding the complex dynamics of ions in plasma confinement and plasma processing of materials. Furthermore, the present work seeks to create a framework for two-fluid modeling of magnetized plasmas with any arbitrary magnetic field profiles. The analysis provided here is supposed to act as a basis for any future work in the respective field.
rate research
Read More
The sheath formation in a weakly magnetized collisionless electronegative plasma consisting of electrons, negative and positive ions has been numerically investigated using the hydrodynamic equations. The electrons and negative ions are assumed to follow Boltzmann relation. A sheath formation criterion has been analytically derived. The paper focuses on studying the sheath structure by varying the electronegativity. It has been observed that the presence of negative ions has a substantial effect on the sheath structure. The observations made in the present work have profound significance on processing plasmas, especially in the semiconductor industry as well as in fusion studies.
The ionization efficiency of helicon plasma discharge is explored by changing the low axial magnetic field gradients near the helicon antenna. The highest plasma density is found for a most possible diverging field near the antenna by keeping the other operating condition constant. Measurement of axial wave number together with estimated radial wavenumber suggests the oblique mode propagation of helicon wave along the resonance cone boundary. Propagation of helicon wave near the resonance cone angle boundary can excite electrostatic fluctuations which subsequently can deposit energy in the plasma. This process has been shown to be responsible for peaking in density in low field helicon discharges, where the helicon wave propagates at an angle with respect to the applied uniform magnetic field. The increased efficiency can be explained on the basis of multiple resonances for multimode excitation by the helicon antenna due to the availability of a broad range of magnetic field values in the near field of the antenna when a diverging magnetic field is applied in the source.
It is well known that additional ionization in the vicinity of a positively biased electrode immersed into a weakly ionized plasma is responsible for a hysteresis in the electrode current-voltage characteristics and the current self-oscillations rise. Here we show both experimentally and theoretically that under certain conditions these phenomena cannot be correctly interpreted once considered separately from the reference electrode current-voltage characteristics. It is shown that small electrodes can be separated into three groups according to the relation between the electrode and the reference electrode areas. Each group is characterized by its own dependence of the collected current on the bias voltage.
An experimental investigation on the periodic and chaotic oscillations in a reflex plasma source in presence of magnetic field is presented. The experiment is conducted in a reflex plasma source, consisting of two cathodes and a ring anode. A penning type DC glow discharge in an uniform axial magnetic field is initiated in the background of argon gas. The current-voltage characteristics near the breakdown voltage show a hysteresis with two distinct discharge current regimes. The effect of magnetic field on the discharge current and floating potential oscillations is studied when the discharge is operated within this hysteresis loop. At a typical axial magnetic field, the discharge transits from high discharge current regime (beyond 4-5 mA), an oscillation free regime, to a low discharge current regime (less than 1 mA). Depending upon the discharge parameters, low discharge current regime shows either the periodic or chaotic oscillation in the frequency range of 1-50 KHz. The frequency of periodic oscillation increases with the increase in magnetic field up to 90 Gauss and with further increase in magnetic field, the periodic oscillation becomes chaotic in nature.
We study the change of the effect of the current quark mass on the inhomogeneous chiral phase in the QCD phase diagram, and discuss the property of the phase transition by the generalized Ginzburg-Landau expansion. The strong external magnetic field spreads this phase over the low chemical potential region even if the current quark mass is finite. This implies that the existence of this phase can be explored by the lattice QCD simulation.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
