In this paper we consider how the dynamical characteristics of streamers are determined by their multidimensional structure. Results from two-dimensional (three-dimensional, cylindrically symmetric) simulations presented at atmospheric pressure for ${\mathrm{N}}_{2}$ and plane-parallel electrodes. Our high-spatial-resolution based on a numerical model which is able to treat wide range electrode configurations (including point-to-plane other complex configurations). This has allowed us make...

A key need for the development and testing of models suitable chemically active, low pressure plasmas is detailed comparisons between model predictions experimental measurements. In this paper, a two-dimensional, axisymmetric fluid an inductively coupled plasma described, are compared to measurements P. A. Miller, G. Hebner, K. E. Greenberg, D. Pochan, B. Aragon [J. Res. Natl. Inst. Stand. Technol. 100, 427 (1995)] electron density, temperature, potential. Comparisons were made in argon...

A two-dimensional (r,z) fluid model has been developed to study plasma transport in inductively coupled plasmas (ICP). Electron heating is treated by assuming a fixed, spatially varying power deposition profile the electron energy balance equation. high aspect ratio ICP reactor geometry studied, with two assumed profiles: uniform and localized within several skin depths of radial wall. The effect neutral gas pressure on uniformity presented for an argon discharge over range 1–20 mTorr....

A two-dimensional (r, z) fluid model is used to study plasma transport in inductively coupled plasmas (ICPS). Electron heating from external RF coil driven at 2 MHz calculated self-consistently by solving for the time-averaged electric field. Radial uniformity has been studied both high (R/L=2.5) and low (R/L=1) aspect ratio ICP reactors with planar or cylindrical coils. The effect of neutral gas pressure on presented Ar discharges 5 20 mTorr. location coils corresponding power deposition...

The scaling laws that control the efficiency of converting ground‐based HF power to ELF by using modulation polar electrojet current is discussed. analysis based on kinetic calculations modification ionospheric conductivity waves in conjunction with experimental results reported from Tromso Max Planck and Alaska high auroral simulation (HIPAS) facilities. It shown can be increased more than a factor 10 4 (1) phasing sweep antenna beam over an area spanned maximum tilt 35°, time scale faster...

Abstract Composite explosives contain pores that collapse under shock wave interaction generating localized regions of heat known to be important in the initiation high explosives. Understanding pore loading is essential create predictive reactive flow models simulate process. While spherical has been thoroughly simulated, other geometries have relatively neglected. Simulating microoscale hot spot nucleation, we analyze effect morphology on post‐shock temperature. Several morphologies yield...

JWL++ is a simple Reactive Flow model that includes time-dependent reaction in prompt detonation. It consists of Murnahan unreacted equation state, JWL reacted EOS, mixer for the two EOS's and single-time-constant exponential rate. The mixing can be done by four ways, using either pressure or plus artificial viscosity rate, also an analytic function equilibrator. reproduces Size Effect detonation front curvature. Detonation failure induced. propagates through arbitrary geometry 3-D without...

view Abstract Citations (86) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Winds from Accretion Disks: Ultraviolet Line Formation in Cataclysmic Variables Shlosman, Isaac ; Vitello, Peter accretion disks cataclysmic variable stars are ubiquitous. Observations by IUE reveal P Cygni-shaped profiles of high-ionization lines which attributed to these winds. We have studied the formation UV emission variables constructing kinematical models...

view Abstract Citations (80) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Active galactic nuclei - Internal dynamics and formation of emission clouds Shlosman, I. ; Vitello, P. A. Shaviv, G. It is shown that cool UV accretion disks, if present in active nuclei, can be sources line-driven winds. Subcritical disks are to capable producing winds optically thin the continuum, which accelerated by radiation pressure lines (i.e., absorption...

The simulation of ion extraction from a quasineutral plasma is described using two-dimensional time-dependent numerical fluid equation code, flow. Ion motion treated the cold continuity and momentum conservation equations in potential field complex structures. An upwind differencing scheme Cartesian coordinates used to solve these equations. electrons are modeled as having Maxwell–Boltzmann distribution, which allows for acoustic effects inside plasma. growth evolution sheaths while...

The efficiency of the mth harmonic electron cyclotron maser interaction for a TE/sub mn1/ gyrotron oscillator is compared with (m-1)th peniotron-like interaction. Identical cavities and beams are used. Start oscillation conditions from weak-field linear theory given, as well optimized nonlinear efficiencies. leads to efficiencies /spl lsim/= 65 percent, while those limited lsim/=25 percent in cases studied.

Abstract A Gurney‐type equation was previously corrected for wall thinning and angle of tilt, now we have added shock wave attenuation in the copper air gap energy loss. Extensive calculations were undertaken to calibrate two new loss mechanisms across all explosives. The Gurney is recommended cylinder use over original 1943 form. effect these corrections add more adiabat values from a relative volume 2 7, with low explosives having largest correction. data pushed up about 15 JWL parameter ω...

High explosive performance and sensitivity is strongly related to the mesoscale defect densities. Bracketing population of hot spots that are active in shocked ignition explosives important for development predictive reactive flow models. By coupling a multiphysics-capable hydrodynamics code (ale3d) with chemical kinetics solver (cheetah), we can parametrically analyze different pore sizes undergoing collapse high pressure shock conditions evolving physical parameter fields. Implementing...

We are investigating a novel insulator concept that involves the use of alternating layers conductors and insulators with periods on order <1 mm. These structures perform many times better (/spl sim/1.5 to >4/spl times/ higher breakdown electric field strength) than conventional in long pulse, short polarity applications. A previously defined scaling law d/sup 0:5/, where d is length, appears apply these new when parameter replaced by layer period d/sub 1/. This observation implies each...

A comprehensive analysis of the ionization rates air by RF fields is presented. The relies on a time‐dependent code which treats electron energization with Fokker‐Planck type model and inelastic energy losses multiple time scale technique. Derivation for parameters interest To D region ionospheric ground‐based transmitters frequency much higher than neutral collision emphasized. study provides physical understanding proces its associated efficiency combining computational results analytic...

The operation of a high harmonic gyro-traveling-wave-tube amplifier which is based on the synchronous interaction rotating beam large orbit, axis-encircling electrons with ${\mathrm{TE}}_{\mathrm{n}1}$ cylindrical waveguide mode described. Principal results include amplification ${\mathrm{TE}}_{81}$ at eighth cyclotron frequency small signal gain 10 dB, an instantaneous bandwidth 4.3%, and saturated power transfer 0.5 kW.

view Abstract Citations (49) References (57) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ultraviolet Line Diagnostics of Accretion Disk Winds in Cataclysmic Variables Vitello, Peter ; Shlosman, Isaac The IUE data base is used to analyze the UV line shapes cataclysmic variables RW Sex, Tri, and V Sge. Observed lines are compared synthetic profiles computed using a model rotating biconical winds from accretion disks. wind calculates ionization structure...

The cylinder test for deriving detonation energies is fully described and analyzed, including the relation between streak camera Fabry-Perot interferometer data. 6, 12.5 19 mm scaled displacements are modified to represent average relative volumes of 2.2, 4.4 7.2. CHEETAH V3.0 introduced with its new all-Hugoniot calibration, which produces most accurate date. Using at three volumes, we find that 107 shots show full burn. Of these, 52 taken as standards an error ±2.6 %. Another 26 higher...

The electron-cyclotron maser interaction provides an extremely efficient means of generating high-power radiation in the millimeter and submillimeter regimes. For devices where both high frequencies low magnetic fields are required, cyclotron-harmonic interactions must be considered. We present here a finear nonlinear analysis TE/sub m11/ whispering-gallery-mode gyrotron. Resonances at mth (m +- 1)th cyclotron harmonic found. start oscillation condition is calculated from linear theory for...

A hydrodynamical treatment of the free expansion into vacuum by a relativistic plasma with an embedded magnetic field is presented. Both linear and spherical geometry are considered. For times when system has expanded to sizes much larger than initial size energy density, number velocity, profiles given. The general features discussed compared those nonrelativistic expansion.

A self-consistent two-dimensional radio frequency inductively coupled glow discharge model has been developed in cylindrical coordinates using a fluid model. The objective of the study is to provide insight into charged species dynamics and investigate their effects on plasma process for methane discharge. includes continuity energy equations electrons continuity, momentum positive negative ions. An electromagnetic that considers electric field due space charge within inductive power...

Abstract Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70 μs −1 . Six unconfined/steel sets of original ANFO and dynamite data are presented. A means comparing confinement effects both at constant radius detonation velocity is Calculations show two qualitatively different modes behavior. For U s / C o ≥1.2, where the zero‐pressure sound speed in steel, we find a sharp shock wave metal. The passes through steel outer wall has jump‐off....

The high-harmonics gyro-traveling-wave tube (gyro-TWT) is a high-power (>or=1-kW) millimeter wave amplifier based on the synchronous interaction of beam large-orbit axis-encircling electrons with high-order cylindrical waveguide mode. Since occurs at high harmonic cyclotron frequency, intense magnetic fields required for conventional fundamental-mode gyro-TWT are not required. A proof-of-principle experiment designed to demonstrate 150-mA, 350-keV electron TE/sub 81/ mode described....

"Ignition & Growth" (I&G) and JWL++ models are compared for a variety of problems. The detonation velocity becomes nearly constant with zoning at the edge convergence, which TATB, is 8 zones/mm I&G 4 JWL++. use pressure in rate makes rapidly decrease as zones coarsened. Using plus artificial viscosity to some power allows correction coarsening zones. In coarse zones, burn fraction turn on independently this feature dominates model behavior. If lags fraction, then maximum will be lower than...