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A detailed study of the x-ray spectra of gold has been inspired by the necessities of the National Ignition Campaign to learn more about the M-band contribution to the total energy balance inside the NIF's hohlraum. For this purpose a survey x-ray spectrometer covering a spectral range from 0.5 to 19.5 angstroms has been added to the the Nike diagnostic suite. This instrument allows simultaneous observation...
X-ray laser-based imaging backlighting was developed at the 1-MA Zebra generator at UNR. Al and Ti star and cylindrical wire arrays were studied using backlighting at the wavelength of 6.65 Å and UV laser diagnostics at 266 nm. X-ray imaging allows for the viewing of the dense core of plasma column during the ablation stages with a resolution of 20 um. X-ray backlighting was provided by hitting a...
Computational models for DC and oscillatory (RF-driven) sheath potentials, arising at metal or dielectric-coated surfaces in contact with plasma, are developed from first principles using particle-in-cell modeling in the VSim FDTD code. These results are used to formulate lumped-element boundary conditions1, applicable in both fluid2 and particle VSim modeling scenarios, wherein sub-grid models for...
The nanosecond electrical explosion of aluminum (Al) wire in vacuum is investigated using a one-dimensional magnetohydrodynamic model with the “cold start” conditions, which describes the severe phase transition from solid state into exploding plasma. Thomas-Fermi equation of state with quantum and exchange corrections, which allows the phase transition from solid to plasma state to be approximately...
Field emission current from single walled carbon nanotubes (SWCNTs) is simulated via the OCTOPUS code implementation of time-dependent density functional theory (TD-DFT), a quantum many electron algorithm capable of solving problems with hundreds to thousands of electrons in the presence of time varying external potentials on massively parallel computer architecture. Simulations were performed in...
High-power diodes that generate intense electron beams are useful in many applications such as generating intense microwave radiation, pumping lasers for driving inertial fusion targets, and producing bremsstrahlung x-rays for flash radiography and nuclear weapon effects simulations. The core component of a high-power diode consists of a two-electrode acceleration gap in which a high voltage pulse...
Wave processes in pre-modulated electron stream interacted with electromagnetic field has been considered in the framework of 2-dim linear theory. Influences of space charge (thin beam model [1]) and finite focusing magnetic field have been taken into account. For describing the interaction the system included excitation equation of rf electric field and equations of rf electron displacements has...
During reentry into the atmosphere, aerospace vehicles are subjected to severe aerothermal heating that causes the surrounding gas to ionize and form a plasma. The analysis of the plasma around the vehicle is useful in developing new strategies and mitigation devices to minimize blackout related issues. Modeling aspects and the simulation results of aerothermal heating, plasma generation and EM wave...
UV illumination switch is often utilized for pulse sharpening in large pulsed power devices. A lot of work has been done for UV illumination switch under nanosecond pulse1 while the switch under microsecond pulse may show different performance2. The purpose of this study is to figure out the breakdown characteristics of UV illumination switch under microsecond pulse. To analyse the development of...
Radio frequency (RF) generators are one of the critical components for RF delivery systems in plasma applications. The main components of a typical RF power delivery system are RF generator, matching network, and plasma power and impedance monitoring device1. The interaction between specifically RF generator and the plasma chamber carries great importance due to dynamic structure of the plasma impedance...
The auxiliary heating systems have already been built in HL-2A nuclear fusion experimental device. The DC high voltage (HV) pulse power supplies are the important components of the auxiliary heating systems. There are two existing HV power supplies which are based on thyristor voltage regulating and star-point controlling technology, respectively. In order to do some research in H-mode, it is necessary...
The complex scenario of extended energy deposition in the solar polar coronal hole and the acceleration of fast solar wind flowing out of this region have been investigated. The transition point from collisional to collisionless plasma in the polar coronal hole may be taken at about one solar radius above the photosphere, and a three-fluid Maxwell model comprising electrons, protons, and alpha-particles...
In geometrically symmetric capacitive radio-frequency plasmas driven by two consecutive harmonics a dc self-bias can be generated as a function of the phase shift between the driving frequencies via the Electrical Asymmetry Effect (EAE) [1]. Recently the Secondary Electron Asymmetry Effect (SEAE) was discovered (T. Lafleur, P. Chabert and J.P. Booth J. Phys. D: Appl. Phys. 46 135201 (2013)): unequal...
At very low gas pressures around 1 Pa the electron heating in capacitive radio frequency discharges is dominated by stochastic heating. In this regime electrons are accelerated by the oscillating sheaths, traverse through the plasma bulk and interact with the opposite sheath. Depending on the driving frequency the energetic electrons can enter the sheaths at different phases. These are i) the collapsing...
An eleven stage flat top type output Marx utilizing sparkgap switches is operated to produce a desired 500 kV output at 10 Hz rep-rate with > 500 J pulse energy to drive a ∼ 20 Ohm load. While this Marx generator utilizes custom-designed spark gaps, the significant progress in semi-conductor pulsed switching technology is evaluated through PSICE modeling of the semiconductor switches integrated...
Intensive development and biomedical application of non-equilibrium atmospheric plasma jet (NEAPJ) facilitates rapid growth of the plasma medicine field. Non-equilibrium atmospheric plasmas are utilized for sterilization, disinfection, cancer treatment, drug delivery, dermatology, wound healing, etc. The NEAPJ facility utilized at the George Washington University (GWU) demonstrated efficacy for treatment...
Some researchers have researched the high-intensity discharge (HID) lamp which is one of the arc lamp with metal vapor, and the line spectrum emitted from the metal vapor is used for improvement of color rendering spectrum. The broad spectrum emitted from continuous spectrum is needed for improvement of color rendering spectrum. Previous research has investigated the spectrum control for the color...
An exact solution of the fluid momentum equation for the incompressible steady-state flow is obtained for the gas streams inside the jet-tube and outside the tube of open air-space. In the solutions the fluid channels of gases as well as the plasmas are described with respect to the reaching distance and the expansion of gases and plasmas with the effects of particle-diffusion and gravity. In the...
In 1889, Friedrich Paschen published a law that describes the voltage at which a gas breaks down into plasma. It describes the dependence of the breakdown voltage on the gas pressure, distance between the electrodes, the secondary electron emission coefficient, and some proportionality constants [1]. A study by V. A. Lisovskiy et al [2] concluded that the original Paschen's law and the modification...
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