Download or read book Numerical Modeling of Suprathermal Electron Transport in Laser produced Plasmas Report Number 36 written by and published by . This book was released on 1976 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supra-thermal electrons can radically alter the dynamics of imploding laser fusion targets by preheating the target material, by transforming energy to a rapid ion blowoff or, due to mean free path effects, decoupling the core from the corona. In order to correctly simulate the dynamics of a laser driven target, it is necessary to develop an accurate physical and computational model of these electrons. The difficulties inherent in this problem can be appreciated by noting that the supra-thermal velocities can vary by over an order of magnitude while the density of the background thermal electron fluid through which they propagate can vary by over four orders of magnitude. Since the supra-thermal mean free-path is proportional to v4/n{sub e}, there can be an eight order of magnitude variation in this scaling parameter. Since the transport of supra-thermal electrons must be followed in both the diffusive and free streaming limits, neither flux limited diffusion models nor truncated moment methods are adequate. A three component model of transport of supra-thermal electrons is developed here to satisfy all requirements discussed in this paper.

Download or read book Suprathermal Electron Transport in Laser produced Plasmas written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A self-consistent, collisional, particle-in-cell scheme has been developed to model the one dimensional transport of suprathermal electrons in laser produced plasmas. This full Monte Carlo approach was taken, since earlier, simpler models have failed to explain an experimentally almost universal anomalous inhibition of thermal transport. The Monte Carlo scheme allows for free-streaming, ion scatter, and self thermalization of the electrons, which are moved in self-consistent E-fields computed with the aid of implicit fluid moments. PIC hydrodynamics for the ions, ponderomotive forces, and resonance and inverse-bremsstrahlung absorption of the light are all accommodated. In application to the anomalous inhibition problem, use of the scheme demonstrates that intrinsic differences in the Monte Carlo, and conventional flux-limited diffusion modelling of the transport results in apparent and real inhibition, explaining the need for strong flux-limiting in the simpler diffusion modelling of experiments.

Download or read book Numerical simulations of suprathermal electron ionisation dynamics and spectral line radiation transfer in short pulse laser produced plasmas written by Asif Khan and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Test of Models for Electron Transport in Laser Produced Plasmas written by and published by . This book was released on 2005 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper examines five different models of electron thermal transport in laser produced spherical implosions. These are classical, classical with a flux limit f, delocalization, beam deposition model, and Fokker-Planck solutions. In small targets, the results are strongly dependent of f for flux limit models, with small f's generating very steep temperature gradients. Delocalization models are characterized by large preheat in the center of the target. The beam deposition model agrees reasonably well with the Fokker-Planck simulation results. For large, high gain fusion targets, the delocalization model shows the gain substantially reduced by the preheat. However flux limitation models show gain largely independent of f, with the beam deposition model also showing the same high gain.

Download or read book Journal de physique written by and published by . This book was released on 2006 with total page 1310 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electron Transport Ion Acoustic Dynamics in Laser produced Plasmas written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis laser-plasma processes are studied at transport and ion time scales. In order to study these processes the particle-in-cell code QNPIC with one spatial dimension and three dimensions in velocity space was developed. Collisional effects are included by a Monte Carlo procedure, and an electric field solver based on the quasineutrality condition has been implemented. This allows long time scale simulations without having to resolve the electron plasma frequency. Collisional heating of the electrons in the laser electric field is one of the major restrictions on the time step in particle-in-cell codes. We have developed a collisional heating procedure that is based on a Langevin equation. It utilizes a Fokker-Planck equation that describes heating time averaged over the laser frequency. This procedure, in conjunction with the fast field solver and procedures to represent collisions, allows simulation of long time scale in laser-plasma interactions without the need to resolve the short time scales to ensure numerical stability and suppress numerical artifacts. We have studied in detail homogeneously heated plasmas and the effects of electron-electron collisions and collisional heating on the electron distribution function. We have suggested a nonlocal, nonlinear heat transport model based on a earlier self consistent nonlocal transport theory that is formally restricted to small (linearized) temperature perturbations. Our model extends this model to the case of finite temperature perturbations. The model is tested successfully in simulations of hot spot relaxation of an initial temperature distribution that corresponds to the instantaneous release of heat into a spatially Gaussian temperature profile and Maxwellian velocity distributions of the electrons. In simulations of collisionally heated hot spots we qualitatively describe the effects of non-Maxwellian velocity distributions on the heat flux and the change of the distribution function due to transpor.

Download or read book Laser plasma Interactions written by R. A. Cairns and published by . This book was released on 1980 with total page 874 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 900 pages. Available in PDF, EPUB and Kindle. Book excerpt: NSA is a comprehensive collection of international nuclear science and technology literature for the period 1948 through 1976, pre-dating the prestigious INIS database, which began in 1970. NSA existed as a printed product (Volumes 1-33) initially, created by DOE's predecessor, the U.S. Atomic Energy Commission (AEC). NSA includes citations to scientific and technical reports from the AEC, the U.S. Energy Research and Development Administration and its contractors, plus other agencies and international organizations, universities, and industrial and research organizations. References to books, conference proceedings, papers, patents, dissertations, engineering drawings, and journal articles from worldwide sources are also included. Abstracts and full text are provided if available.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1987 with total page 1294 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1983 with total page 1144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Documentation of Plasma Physics Pt 1 Experimental Plasma Physics and Theoretical Plasma Physics written by and published by . This book was released on 1981 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inertial Fusion Sciences and Applications 2005 written by Jean-Claude Gauthier and published by . This book was released on 2006 with total page 1288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1983 with total page 962 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1987 with total page 1122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inertial Confinement Fusion written by James J. Duderstadt and published by John Wiley & Sons. This book was released on 1982 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Use of Services for Family Planning and Infertility United States 1982 written by Gerry E. Hendershot and published by . This book was released on 1988 with total page 982 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 1982 statistics on the use of family planning and infertility services presented in this report are preliminary results from Cycle III of the National Survey of Family Growth (NSFG), conducted by the National Center for Health Statistics. Data were collected through personal interviews with a multistage area probability sample of 7969 women aged 15-44. A detailed series of questions was asked to obtain relatively complete estimates of the extent and type of family planning services received. Statistics on family planning services are limited to women who were able to conceive 3 years before the interview date. Overall, 79% of currently mrried nonsterile women reported using some type of family planning service during the previous 3 years. There were no statistically significant differences between white (79%), black (75%) or Hispanic (77%) wives, or between the 2 income groups. The 1982 survey questions were more comprehensive than those of earlier cycles of the survey. The annual rate of visits for family planning services in 1982 was 1077 visits /1000 women. Teenagers had the highest annual visit rate (1581/1000) of any age group for all sources of family planning services combined. Visit rates declined sharply with age from 1447 at ages 15-24 to 479 at ages 35-44. Similar declines with age also were found in the visit rates for white and black women separately. Nevertheless, the annual visit rate for black women (1334/1000) was significantly higher than that for white women (1033). The highest overall visit rate was for black women 15-19 years of age (1867/1000). Nearly 2/3 of all family planning visits were to private medical sources. Teenagers of all races had higher family planning service visit rates to clinics than to private medical sources, as did black women age 15-24. White women age 20 and older had higher visit rates to private medical services than to clinics. Never married women had higher visit rates to clinics than currently or formerly married women. Data were also collected in 1982 on use of medical services for infertility by women who had difficulty in conceiving or carrying a pregnancy to term. About 1 million ever married women had 1 or more infertility visits in the 12 months before the interview. During the 3 years before interview, about 1.9 million women had infertility visits. For all ever married women, as well as for white and black women separately, infertility services were more likely to be secured from private medical sources than from clinics. The survey design, reliability of the estimates and the terms used are explained in the technical notes.