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Direct Measurements Of Nonlocal Heat Flux In Laser Produced Coronal Plasmas Using Thomson Scattering From Electron Plasma Waves
Download Direct Measurements Of Nonlocal Heat Flux In Laser Produced Coronal Plasmas Using Thomson Scattering From Electron Plasma Waves full books in PDF, epub, and Kindle. Read online Direct Measurements Of Nonlocal Heat Flux In Laser Produced Coronal Plasmas Using Thomson Scattering From Electron Plasma Waves ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Direct Measurements of Nonlocal Heat Flux in Laser-produced Coronal Plasmas Using Thomson Scattering from Electron-plasma Waves by : Robert James Henchen
Download or read book Direct Measurements of Nonlocal Heat Flux in Laser-produced Coronal Plasmas Using Thomson Scattering from Electron-plasma Waves written by Robert James Henchen and published by . This book was released on 2018 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Thermal transport is a fundamental process in plasma physics that is not well understood. Historically, local models have been used to describe the heat flux in plasmas but artificially limit the flux at even modest temperature gradients. This Thesis studies electron thermal transport in laser-produced coronal plasmas using a novel Thomson scattering technique. Thomson scattering is sensitive to changes in the electron distribution function caused by heat flux. The experiments show that nonlocal effects must be included in regions where the plasma was not collisional enough for classical theory to be valid. Vlasov-Fokker-Planck simulations self consistently calculated the electron distribution functions used to reproduce the measured Thomson scattering spectra and to determine the heat flux. Measured heat flux values were up to 40% smaller than classical values inferred from the measured plasma conditions in this region. This is the first direct measurement of nonlocal heat flux in plasmas. In the opposite limit, classical theory matched the observed Thomson scattering data. Multigroup nonlocal simulations overestimated the measured heat flux."--Page xi.
Book Synopsis Measurement of Heat Propagation in a Laser Produced Plasma by : J. Edwards
Download or read book Measurement of Heat Propagation in a Laser Produced Plasma written by J. Edwards and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the observation of a nonlocal heat wave by measuring spatially and temporally resolved electron temperature profiles in a laser produced nitrogen plasma. Absolutely calibrated measurements have been performed by resolving the ion-acoustic wave spectra across the plasma volume with Thomson scattering. We find that the experimental electron temperature profiles disagree with flux-limited models, but are consistent with transport models that account for the nonlocal effects in heat conduction by fast electrons.
Book Synopsis Spatially and Temporally Resolved Temperature and Density Measurements in a Laser Produced Plasma by : Jason William Knight
Download or read book Spatially and Temporally Resolved Temperature and Density Measurements in a Laser Produced Plasma written by Jason William Knight and published by . This book was released on 2004 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thomson Scattering in the Corona of Laser-produced Gold Plasmas by :
Download or read book Thomson Scattering in the Corona of Laser-produced Gold Plasmas written by and published by . This book was released on 1996 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thomson scattering measurements of the electron temperature in laser- produced gold plasmas are presented. We irradiated a flat gold disk target with one laser beam of the Nova laser facility. A second laser beam probed the plasma at a distance of 500[mu]m with temporally resolved Thomson scattering. The electron temperature measurements are compared with hydrodynamic simulations using the code LASNEX for experiments applying smoothed and unsmoothed heater beams. In case of an unsmoothed heater beam the simulations predict temperatures which are about 40% higher than our measured data. Although the agreement is improved for a smoothed heater beam, discrepancies exist in the decay phase of the plasma. We discuss possible explanations for these observations.
Book Synopsis Thomson Scattering Techniques in Laser Produced Plasmas by : J. S. Ross
Download or read book Thomson Scattering Techniques in Laser Produced Plasmas written by J. S. Ross and published by . This book was released on 2006 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thomson scattering has been shown to be a valuable technique for measuring the plasma conditions in laser produced plasmas. Measurement techniques are discussed that use the ion-acoustic frequency measured from the collective Thomson-scattering spectrum to extract the electron temperature, ion temperature, plasma flow, and electron density in a laser produced plasma. In a recent study, they demonstrated a novel Thomson-scattering technique to measure the dispersion of ion-acoustic fluctuations that employing multiple color Thomson-scattering diagnostics. They obtained frequency-resolved Thomson-scattering spectra of the two separate thermal ion-acoustic fluctuations with significantly different wave vectors. This new technique allows a simultaneous time resolved local measurement of electron density and temperature. The plasma fluctuations are shown to become dispersive with increasing electron temperature. Furthermore, a Thomson-scattering technique to measure the electron temperature profile is presented where recent experiments have measured a large electron temperature gradient (Te = 1.4 keV to Te = 3.2 keV over 1.5-mm) along the axis of a 2-mm long hohlraum when heated asymmetrically.
Book Synopsis Measurements of Relativistic Effects in Collective Thomson Scattering at Electron Temperatures Less Than 1 KeV by : James Steven Ross
Download or read book Measurements of Relativistic Effects in Collective Thomson Scattering at Electron Temperatures Less Than 1 KeV written by James Steven Ross and published by . This book was released on 2010 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simultaneous scattering from electron-plasma waves and ion-acoustic waves is used to measure local laser-produced plasma parameters with high spatiotemporal resolution including electron temperature and density, average charge state, plasma flow velocity, and ion temperature. In addition, the first measurements of relativistic modifications in the collective Thomson scattering spectrum from thermal electron-plasma fluctuations are presented [1]. Due to the high phase velocity of electron-plasma fluctuations, relativistic effects are important even at low electron temperatures (T/e
Book Synopsis Thomson Scattering from Inertial Confinement Fusion Plasmas by :
Download or read book Thomson Scattering from Inertial Confinement Fusion Plasmas written by and published by . This book was released on 1997 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thomson scattering has been developed at the Nova laser facility as a direct and accurate diagnostic to characterize inertial confinement fusion plasmas. Flat disks coated with thin multilayers of gold and beryllium were with one laser beam to produce a two ion species plasma with a controlled amount of both species. Thomson scattering spectra from these plasmas showed two ion acoustic waves belonging to gold and beryllium. The phase velocities of the ion acoustic waves are shown to be a sensitive function of the relative concentrations of the two ion species and are in good agreement with theoretical calculations. These open geometry experiments further show that an accurate measurement of the ion temperature can be derived from the relative damping of the two ion acoustic waves. Subsequent Thomson scattering measurements from methane-filled, ignition-relevant hohlraums apply the theory for two ion species plasmas to obtain the electron and ion temperatures with high accuracy. The experimental data provide a benchmark for two-dimensional hydrodynamic simulations using LASNEX, which is presently in use to predict the performance of future megajoule laser driven hohlraums of the National Ignition Facility (NIF). The data are consistent with modeling using significantly inhibited heat transport at the peak of the drive. Applied to NIF targets, this flux limitation has little effect on x- ray production. The spatial distribution of x-rays is slightly modified but optimal symmetry can be re-established by small changes in power balance or pointing. Furthermore, we find that stagnating plasma regions on the hohlraum axis are well described by the calculations. This result implies that stagnation in gas-filled hohlraums occurs too late to directly affect the capsule implosion in ignition experiments.
Book Synopsis Characterization of High-Temperature Laser-Produced Plasmas Using Thomson Scattering by : S. Ross
Download or read book Characterization of High-Temperature Laser-Produced Plasmas Using Thomson Scattering written by S. Ross and published by . This book was released on 2005 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultraviolet Thomson scattering has been fielded at the Omega Laser Facility to achieve accurate measurements of the plasma conditions in laser-produced high-temperature plasmas. Recent applications to hohlraum targets that have been filled with CH gas or SiO{sub 2} foams have demonstrated a new high temperature plasma regime of importance to laser-plasma interaction studies in a strongly damped regime such as those occurring in indirect drive inertial confinement fusion experiments. The Thomson scattering spectra show the collective ion acoustic features that fit the theory for two ion species plasmas and from which we infer the electron and ion temperature. We find that the electron temperature scales from 2-4 keV when increasing the heater beam energy into the hohlraum from 8-17 kJ, respectively. Simultaneous measurements of the stimulated Raman scattering from a green 527 nm interaction beam show that the reflectivity decreases from 20% to 1% indicating that this instability is strongly damped at high temperatures. These findings support green laser beams as possible driver option for laser-driven fusion experiments.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Book Synopsis Picosecond Thomson-scattering Spectroscopy Investigation of Thermodynamics in Laser-plasma Amplifiers by : Andrew S. Davies
Download or read book Picosecond Thomson-scattering Spectroscopy Investigation of Thermodynamics in Laser-plasma Amplifiers written by Andrew S. Davies and published by . This book was released on 2019 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Ultrafast electron plasma wave dynamics, Thermodynamics, and collisions are fundamental processes in laser-plasma physics that is not well understood. Historically, models have used simple approximations to describe the Thermodynamics in laser-plasma devices or artificially assumed constant plasma conditions. This thesis studies the picosecond ionization and Thermodynamics in laser-produced underdense plasmas using a novel Thomson scattering technique. The unprecedented temporal resolution of the Thomson spectra provided a measurement of collisional electron plasma waves that were modeled to extract the picosecond evolution of the electron temperature and density. This revealed a transition in the plasma-wave dynamics from an initially cold, collisional state to a quasi-stationary, collisionless state. The Thomson-scattering spectra were compared with theoretical calculations of the fluctuation spectrum using either a conventional Bhatnagar Gross Krook (BGK) collision operator or the rigorous Landau collision terms: the BGK model overestimates the electron temperature by 50% in the most-collisional conditions. These picosecond electron temperature and density measurements can be applied to laser-plasma devices that require knowledge of the rapidly evolving plasma conditions, such as a Raman plasma amplifier. These results indicate that the rapidly evolving conditions would result in a strong detuning that would limit the performance of laser-plasma amplifiers"--Page xii.
Book Synopsis Thomson Scattering Measurements of Heat Flow in a Laser Produced Plasma by : James Alan Hawreliak
Download or read book Thomson Scattering Measurements of Heat Flow in a Laser Produced Plasma written by James Alan Hawreliak and published by . This book was released on 2004 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thomson Scattering Measurements of Mast Plasmas by : R. M. Patrick
Download or read book Thomson Scattering Measurements of Mast Plasmas written by R. M. Patrick and published by . This book was released on 1965 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of Thomson scattering from the plasma electrons were created by high speed shock waves in a magnetic annular shock tube (MAST) used to determine the electron density behind the shock waves, and some preliminary measurements of the electron velocity distribution. A Q-switch ruby laser furnished the light beam which was scattered by the plasma electrons. A rotating quartz prism furnished the Q-switching of the optical cavity for the ruby laser, and rather long Q-switched pulses were obtained (between 10 to the -7th power and 10 to the -6th power sec duration). The power level during the Q-switched pulse was between 30 and 100 megawatts. Rayleigh scattering from an air sample at various pressures was used to calibrate the power output of the laser and gave a simultaneous measure of the laser output power for all of the tests, while the Thomson scattering was being measured. The measurements of the electron density using the Thomson scattering and the plasma continuum intensities agreed within the scatter of the data. The electron temperature measurements obtained with the Thomson scattering showed that the electron temperature increased with increasing shock speed for a given initial condition. (Author).
Download or read book Science Abstracts written by and published by . This book was released on 1992 with total page 1228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thomson-Scattering Measurements in the Collective and Non-collective Regimes in Laser Produced Plasmas by :
Download or read book Thomson-Scattering Measurements in the Collective and Non-collective Regimes in Laser Produced Plasmas written by and published by . This book was released on 2010 with total page 10 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 1986 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurements of Relativistic Effects in Collective Thomson Scattering at Electron Temperatures Less Than 1 KeV. by :
Download or read book Measurements of Relativistic Effects in Collective Thomson Scattering at Electron Temperatures Less Than 1 KeV. written by and published by . This book was released on 2010 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simultaneous scattering from electron-plasma waves and ion-acoustic waves is used to measure local laser-produced plasma parameters with high spatiotemporal resolution including electron temperature and density, average charge state, plasma flow velocity, and ion temperature. In addition, the first measurements of relativistic modifications in the collective Thomson scattering spectrum from thermal electron-plasma fluctuations are presented [1]. Due to the high phase velocity of electron-plasma fluctuations, relativistic effects are important even at low electron temperatures (Te
Book Synopsis Temperature Determination in X-Ray Laser Plasmas by Thomson Scattering by : D. M. Villeneuve
Download or read book Temperature Determination in X-Ray Laser Plasmas by Thomson Scattering written by D. M. Villeneuve and published by . This book was released on 1992 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thomson scattering diagnostics were used to measure electron and ion temperatures in plasmas similar to those used for x-ray lasers. These measurements were compared with predictions of a hydrodynamic simulation. Experimental measurements which can test the accuracy of the codes' predictions can be used to 'calibrate' the codes, and hence lead to either code improvements or an increased confidence in the codes' accuracy. Experiments were performed with plasmas produced from a laser spot focused on solid targets of carbon, germanium and tantalum. The electron temperature could be measured as a function of time at different locations in the plasma, for various laser intensities.
