Breakdown Process of Pseudospark Discharge Using the Various Discharge Module

2014 ◽  
Vol 670-671 ◽  
pp. 1012-1015
Author(s):  
Xiao Wei Gu
Keyword(s):  
Gas Phase ◽  
Theoretical Foundation ◽  
Secondary Electron Emission ◽  
Design Parameters ◽  
Physical Processes ◽  
Particle In Cell ◽  
Breakdown Process ◽  
Neutral Gas ◽  
Pseudospark Discharge ◽  
Electrons And Ions

A argon Pseudospark discharge is studied and modelled with our developed simulation program. The structure of our code is flexible and transparent. The modular structure is divided into three main parts: electromagnetics module which forms the heart of the model, the neutral gas module, and the chemical reaction module. The above three parts with the plasma module are controlled by the user. The strong modularity makes the code easy to handle and easy to adjust or expand. This project will do in-depth numerical simulation for the study of the inception of breakdown characteristics via a electrostatic particle-in-cell plus Monte-Carlo collision method. The model tracks the trajectories of both electrons and ions, including ionizing collisions in the gas phase by electrons and ions, and secondary electron emission by ions on surfaces. The result indicated the pseudospark discharge breakdown process mainly induced by field emission.The peak discharge current is found to be dependent on gas pressure,electrode borehole diameter. The effect of these design parameters on the peak anode current has been analysed. Simulate the discharge breakdown physical processes for the Pseudospark in order to lay the theoretical foundation for the optimize and improve the pulse power electron beam.

scholarly journals Electron-Promoted Desorption from Water Ice Surfaces: Neutral Gas-Phase Products

2017 ◽  
Vol 1 (4) ◽  
pp. 209-215 ◽  
Author(s):  
Ali G. M. Abdulgalil ◽  
Alexander Rosu-Finsen ◽  
Demian Marchione ◽  
John D. Thrower ◽  
Mark P. Collings ◽  
...  
Keyword(s):  
Gas Phase ◽  
Water Ice ◽  
Neutral Gas ◽  
Ice Surfaces

scholarly journals Observation and Modeling of Optical Emission Patterns and Their Transitions in a Penning Discharge

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
C. C. Klepper ◽  
R. C. Hazelton ◽  
F. Barakat ◽  
M. D. Keitz ◽  
J. P. Verboncoeur
Keyword(s):  
Fusion Energy ◽  
Optical Emission ◽  
Nonlinear Dependence ◽  
Sensor Technology ◽  
Gaseous Species ◽  
Optical Signals ◽  
Particle In Cell ◽  
Neutral Gas ◽  
Minority Species ◽  
Mode Transitions

A Penning discharge tube has been used as the excitation source for optical detection of gaseous species concentrations in a neutral gas. This type of diagnostic has been primarily used in magnetic fusion energy experiments for the detection of minority species in the effluent gas (e.g., for helium detection in a deuterium background). Recent innovations (US Patent no. 6351131, granted February 26, 2002) have allowed for extension of the operation range from <1 Pa to as high as 100 Pa and possibly beyond. This is done by dynamically varying the gauge magnetic field and voltage to keep the optical signals nearly constant (or at least away from a nonlinear dependence on the pressure). However, there are limitations to this approach, because the Penning discharge can manifest itself in a number of modes, each exhibiting a different spatial emission pattern. As a result, varying the discharge parameters can cause the gauge to undergo transitions between these modes, disrupting any intended monotonic dependence of the overall emission on the varied parameter and hence any predicable impact on the emission. This paper discusses some of the modes observed experimentally using video imaging of the discharge. It also presents a first successful application, a particle-in-cell (PIC) code, to simulate these modes and a mode transition. The hope is that a good understanding of the physics involved in the mode transitions may allow for methods of either avoiding or suppressing such transitions. This would aid in broadening the use of this plasma-based sensor technology.

Development of a Latching Valve for Micro-Chem-Lab™

1999 ◽  
Author(s):  
C. Channy Wong ◽  
Douglas R. Adkins ◽  
Ronald P. Manginell ◽  
Gregory C. Frye-Mason ◽  
Peter J. Hesketh ◽  
...  
Keyword(s):  
Power Consumption ◽  
Gas Phase ◽  
Flow Rate ◽  
Integrated System ◽  
Dead Volume ◽  
Design Parameters ◽  
Working Fluid ◽  
Driving Voltage ◽  
Magnetic Actuation ◽  
Phase Detection

Abstract An integrated microsystem to detect traces of chemical agents (μChemLab™) is being developed at Sandia for counter-terrorism and nonproliferation applications. This microsystem has two modes of operation: liquid and gas phase detection. For the gas phase detection, we are integrating these critical components: a preconcentrator for sample collection, a gas chromatographic (GC) separator, a chemically selective flexural plate wave (FPW) array mass detector, and a latching valve onto a single chip. By fabricating these components onto a single integrated system (μChemLab™ on a chip), the advantages of reduced dead volume, lower power consumption, and smaller physical size can be realized. In this paper, the development of a latching valve will be presented. The key design parameters for this latching valve are: a volumetric flow rate of 1 mL/min, a maximum hold-off pressure of 40 kPa (6 psi), a relatively low power, and a fast response time. These requirements have led to the design of a magnetically actuated latching relay diaphragm valve. Magnetic actuation is chosen because it can achieve sufficient force to effectively seal against back pressure and its power consumption is relatively low. The actuation time is rapid, and valve can latch in either an open or closed state. A corrugated parylene membrane is used to separate the working fluid from internal components of the valve. Corrugations in the parylene ensure that the diaphragm presents minimum resistance to the actuator for a relativley large deflection. Two different designs and their performance of the magnetic actuation have been evaluated. The first uses a linear magnetic drive mechanism, and the second uses a relay mechanism. Preliminary results of the valve performance indicates that the required driving voltage is about 10 volts, the measured flow rate is about 50 mL/min, and it can hold off pressure of about 5 psi (34 kPa). Latest modifications of the design show excellent performance improvements.

Neutral Gas Phase Metallicities Associated with Dwarf Galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 309-312
Author(s):  
Sandhya M. Rao ◽  
David A. Turnshek ◽  
Eric M. Monier
Keyword(s):  
Gas Phase ◽  
Absorption Line ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Neutral Gas ◽  
Quasar Spectra ◽  
Clear Cases

AbstractAbsorption line spectroscopy of foreground gas in the spectra of background quasars has revealed some clear cases where neutral gas is present and associated with dwarf galaxies. Spectroscopy of Lyα and low-ionization metal lines can be combined to derive neutral gas phase metallicities. The damped Lyα absorbers (DLAs) in quasar spectra are the clearest cases of absorption by predominantly neutral gas regions. Here we present some results on neutral gas phase metallicities for cases where the DLA is clearly associated with a dwarf galaxy. We find that the neutral gas phase metallicities in these systems are similar to those in other DLAs. We argue that there may be many unrecognized cases where a DLA is actually associated with a dwarf galaxy even though there is a luminous galaxy within 100 kpc of the quasar sightline.

scholarly journals Photospheric Sources of Magnetic Field Aligned Currents

1983 ◽  
Vol 71 ◽  
pp. 601-603
Author(s):  
Ake Nordlund
Keyword(s):  
Magnetic Field ◽  
Momentum Transfer ◽  
Coronal Magnetic Field ◽  
Small Scale ◽  
Solar Photosphere ◽  
Electron Component ◽  
Neutral Gas ◽  
Electrons And Ions ◽  
Density Of Electrons ◽  
Gas Component

Possible (small-scale) photospheric sources of coronal magnetic field aligned currents are discussed. Such currents are equivalent to local (small-scale) twists of the coronal magnetic field, and may cause field topologies that are (MHD or resistively) unstable, and thus contribute to the (small-scale) coronal activity.One electro-motive force associated with photospheric magnetic fields is due to the asymmetry between ions and electrons as agents of conductivity and as agents of momentum transfer to the (dominant) neutral gas component. In the solar photosphere, where only some of the easily ionized heavier elements (Mg, Si, Fe, ...) are significantly ionized, the ratio of number density of electrons and ions to neutrals is very small, of the order of the total abundance of these elements, which is of the order 10-4, by number. Due to the larger electron than ion mobility, electric currents are mainly carried by the electron component of the plasma whereas, because of the ions greater momentum transfer to the neutrals in collisions, the friction between the charged and the neutral components of the plasma is mainly due to the ions. Thus, the Lorenz force i x B acts mainly on the electron component of the plasma, whereas the balancing gas pressure gradient and gravity terms act mainly on the neutral component.

scholarly journals Ion-acoustic shocks with reflected ions: modelling and particle-in-cell simulations

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
T. V. Liseykina ◽  
G. I. Dudnikova ◽  
V. A. Vshivkov ◽  
M. A. Malkov
Keyword(s):  
Particle Accelerators ◽  
Collisionless Shock ◽  
Astrophysical Plasmas ◽  
Particle In Cell ◽  
Electrons And Ions ◽  
Ion Acoustic ◽  
Main Driver ◽  
Real Mass ◽  
Astrophysical Shocks ◽  
The One

Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms whereby they accelerate particles, remains incomplete. We present here the results of numerical modelling of an ion-acoustic collisionless shock based on the one-dimensional kinetic approximation for both electrons and ions with a real mass ratio. Special emphasis is paid to the shock-reflected ions as the main driver of shock dissipation. The reflection efficiency, the velocity distribution of reflected particles and the shock electrostatic structure are studied in terms of the shock parameters. Applications to particle acceleration in geophysical and astrophysical shocks are discussed.

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