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A two-dimensional particle-in-cell simulation has been developed to study density enhancement of capacitively coupled rf discharges with multi-slit electrodes. The observed density increase is shown to result from a hollow cathode effect that takes place within the multi-slit electrode configuration, which forms as a result of secondary electron emission due to ion bombardment. By investigating the...
Microhollow cathode discharge (MHCD) can provide high density of initial electrons under pulse voltage, which is used to ignite efficiently a gas switch discharge at an atmospheric pressure. The structure of microhollow cathode is two electrodes divided by about 200µm thick dielectric and threaded by about 100µm hollow. Array microhollow cathode discharge (MHCD) was operated at atmospheric with 2...
The discharge efficiency in microdischarge cells strongly depends on the shape of the sustain waveform. Various shapes, such as the ramped-square sustain waveform and the sustain waveform with auxiliary address short pulse, have been studied to improve the discharge efficiency1, 2.
Previous investigations of exploding radial foils have shown the formation of a dense highly-collimated hypersonic axial plasma jet in the early stages of the foil explosion. In this case a thin load foil is pressed at an outer annulus held at ground, and contacted in the center by a small straight rod cathode driven by a 1MA-in-100ns pulse from COBRA. Recent experiments focus on the initial jet development...
A magnetron structure using field emission cathodes has been modeled with the Air Force Research Laboratory particle-in-cell code ICEPIC and the two-dimensional particle trajectory simulation Lorentz2E1. For the particle trajectory modeling the cathode has a distributed structure comprised of field emitters instead of the traditional thermionic cathode. The cathode is designed with facet plates with...
The plasma-surface interaction in the presence of strong thermionic or secondary electron emission has been studied theoretically and experimentally both as a basic phenomenon and in relation to numerous plasma applications such as, for example, cathodes, emissive probes, divertor plasma, surface discharges, dusty plasmas, plasma thrusters and plasma processing. In a typical low-pressure gas discharge,...
Space charge limited current serves as a basic theoretical prediction for application of high current diodes and other vacuum electronics devices in field of non-neutral plasma physics. Classical Child-Langmuir law (CL law) analytically demonstrates maximum steady current density (space-charge-limited current density) transported before virtual cathode formation across a certain distance under a potential...
Given that the development of future plasma energetics depends on the application and control of nonequlibrium, anisotropic electron energy distribution functions (EEDF) in plasmas, the development of methods to measure and control EEDF is of great importance.
A treecode numerical method was first introduced by Barnes and Hut in astrophysics [1] for simulation of many-body particle systems interacting in a gravitational field. Main advantage of this newly developing method is that it is grid-free, i.e. there is no need to define a grid in advance. This means that during a simulation of the motion of particles in external field, particles are grouped in...
Calabazas Creek Research, Inc. (CCR) is continuing research on controlled porosity reservoir (CPR) cathodes1. In addition to thermionic dispenser cathodes, CCR is teamed with the Institute for Research in Electronics and Applied Physics (IREAP) at the University of Maryland to apply this technology to cesiated dispenser photocathodes. CPR technology provides increased emission uniformity with longer...
Recently a new device namely micro-cathode arc thruster (μCAT) based on vacuum arc discharge has been developed for the spacecraft propulsion application1. The μCAT is a micro-Newton level thrust device that employs a magnetic field and is suited for the long-time operation of micro-thruster for the nano-satellite propulsion such as Cubesats2, 3.
The possibility of use cold cathodes as an electron source in vacuum tube device has been already demonstrated [1]. Using cold cathodes instead of thermionic ones could have many advantages [2], in particular it can increase the efficiency of the tube system since the power consumption of the cathode heater is neglected. For the realization of electron gun with cold cathode an extracting grid near...
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