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Showing 1 to 20 of 26 for “"Plasma sheath"”.
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The Effects of Collisions on Plasma-Sheath Transition
The plasma sheath is essential for understanding the plasma-material interaction (PMI) since it regulates the plasma particle and energy fluxes to the wall. The key concept in sheath theory is the Bohm criterion that gives the lower bound of the plasma exit flow speed, also known as the Bohm speed. …
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The effect of a plasma sheath on hypersonic flight communications
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1990.
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Impact of ion-neutral collisions in fluid models of plasma sheath
… self-consistent fluid modeling of argon plasmas in DC discharges, including the sheath regions, is presented. Comparison of the charged species density, electron mean energy, plasma potential and ion velocity profiles with the profiles obtained by other fluid models and the profiles …
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Observation of plasma sheath modulation in the plasma bipolar junction transistor
Modulation of the plasma sheath in a plasma bipolar junction transistor (PBJT) is observed for base inputs of less than one volt. Using the recorded data, along with a collisional, high-voltage sheath model developed herein, a 359% increase in the secondary electron emission coefficient of the …
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Multiscale numerical simulations of the magnetized plasma sheath with massively parallel electrostatic particle-in-cell code
Understanding the physics of the plasma boundary and plasma-surface interactions is one of the key scientific challenges in fusion science and engineering. Large-scale integrated simulations and high-performance computing can provide valuable insights on the dynamic phenomena involved at the …
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Emitting Wall Boundary Conditions in Continuum Kinetic Simulations: Unlocking the Effects of Energy-Dependent Material Emission on the Plasma Sheath
… Hall thruster and the tokamak, understanding the plasma-material interactions which take place at the wall is important for improving performance and preventing failure due to material degradation. In the region near a surface, the plasma sheath forms and regulates the electron and ion fluxes into …
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Plasma simulation with a dielectric object in the presence of an ion flow
Recent dusty plasma experiments have investigated the crystallization of dust grains near the edge of a plasma sheath. Some theories were proposed to explain the crystallization mechanisms. The purpose of this simulation work is to study the electrostatics of a dielectric object immersed in a …
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The study of overlapping sheath and dust particle structures in dusty plasma.
Complex (dusty) plasma consists of plasma and dust particles which vary in size from nanometer to millimeter in diameter. Complex plasma exists across many different environments, and can be found in environments from the cosmos to industry. Due to plasma fluxes to its surface, a dust particle …
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Batch-microfabricated miniaturized planar arrays of Langmuir probes for reentry plasma diagnostics and nanosatellites
… atmosphere, a high-density and low-temperature plasma sheath forms around it due to shock heating of the surrounding air and ablation of the heat shield material, which leads to the dissociation and ionization of the background atmosphere. The plasma sheath that surrounds the spacecraft affects …
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The effects of moving electron density fluctuations on time domain reflectometry in plasmas
… reflectometry response of a one-dimensional cold plasma sheath are considered. Numerical solutions of the Helmholtz wave equation, which describes the electric field of a normally incident plane wave in a specified static electron density profile, are used. Included in this work is a study of the …
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Supersonic Constricted Plasma Flows
… in space. A weakly ionised capacitively coupled plasma is ignited in the flowing Ar gas propellant within a constricted discharge chamber at 1 Torr using less than 10 W of radiofrequency power. The discharge can operate either continuously or in rapid pulsed mode since plasma breakdown initiates …
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Supersonic Constricted Plasma Flows
… in space. A weakly ionised capacitively coupled plasma is ignited in the flowing Ar gas propellant within a constricted discharge chamber at 1 Torr using less than 10 W of radiofrequency power. The discharge can operate either continuously or in rapid pulsed mode since plasma breakdown initiates …
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Fully kinetic particle-in-cell simulations of plasma-surface-dust interactions for lunar exploration
… exposed to solar radiation and solar wind plasma, is electrically charged by the bombardment of solar wind plasma and emission/collection of photoelectrons. Additionally, lunar dust grains can also get charged and levitated from the surface under the influence of the electric field as well …
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Continuum Kinetic Simulations of Plasma Sheaths and Instabilities
A careful study of plasma-material interactions is essential to understand and improve the operation of devices where plasma contacts a wall such as plasma thrusters, fusion devices, spacecraft-environment interactions, to name a few. This work aims to advance our understanding of fundamental …
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Radio frequency driven direct current electron beam source
… for feature charge neutralization during plasma etching. A low pressure (approximately 2 – 20 mTorr) inductively coupled plasma provides ions which impinge on a high secondary electron emission coefficient anodized aluminum (Al2O3) cathode surface. A separate 13.56 MHz radio frequency bias …
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Experimental probe-induced complex RF plasma phenomena.
Plasma has long been studied in its own right as a state of matter, but the addition of particles large compared to its basic constituents yields a host of complicated behavior that was not predicted theoretically. Levitated micrometer-sized particles in the sheath of a RF plasma have previously …
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Removal of organic contaminants from lithographic materials
… traditional methods. Preliminary research into a plasma-based method to clean organic contaminants from lithographic materials constructed an experimental device that demonstrated the removal of both polystyrene latex nanoparticles (representing hydrocarbon contamination) in the range of 30 nm to …
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Diagnostics for ionized physical vapor deposition chambers
… the wafer plane due to the electric field of the plasma sheath. However from simulation results the ion flux from a magnetron discharge has a narrow angular distribution and this distribution is becoming more significant as the aspect ratio increases. In order to confirm and adjust this predicted …
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Application of Ab-initio Quantum Chemistry Techniques to Hypersonic Flows for Plasma Blackout Alleviation
Plasma blackout in hypersonic flows produced by weakly-ionized air plasma sheaths is a phenomenon that attenuates or completely blocks communications with vehicles flying in a high-enthalpy flow environment. The ability to mitigate this issue can be useful from various re-entry vehicles to …
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Improved performance of the hPIC particle-in-cell code by incorporating a new non-uniform implicit mesh based on the PUMI infrastructure
… meshes are inefficient at capturing the high plasma gradients in a Scrape-Off-Layer (SOL). Especially in the magnetic and electrostatic sheaths forming in front of the material surfaces. The hPIC Particle In Cell code developed previously at UIUC has been modified to incorporate a new …
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