Download or read book Thomson Scattering for Determining Electron Concentrations and Temperatures in an Inductively Coupled Plasma 1 Assessment of the Technique for a Lo Flow Low Power Plasma written by Kim A. Marshall and published by . This book was released on 1988 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron number densities and electron temperatures have been measured by multichannel Thomson scattering in a low-flow low-power inductively coupled plasma. Preliminary electron-concentration values agree well with those previously determined, and spatial variation in both electron concentration and temperature are largely consistent with existing models of the ICP. One difference is that aqueous aerosol was found here to depress the electron number density throughout the plasma. Unfortunately, the intensities measured in the wings of the Thomson-scattering spectrum large uncertainties, making data analysis difficult and the measured electron temperatures less reliable than desired.

Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1988-06 with total page 616 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 1987 with total page 1124 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 1988 with total page 1132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thomson Scattering for Determining Electron Concentrations and Temperatures in an Inductively Coupled Plasma 2 Description and Evaluation of a Multichannel Instrument written by Kim A. Marshall and published by . This book was released on 1988 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new instrument has been assembled to measure Thomson scattering from an inductively coupled plasma. Unlike previous designs, the new system employs a fiber-optic array to measure simultaneously up to 12 channels on a Thomson-scattering spectrum. Shutters enable either side of the nominally symmetrical Thomson spectrum to be examined, or permit summing equally spaced channels on opposite sides of the spectrum from the incident laser wavelength. A central channel, use to monitor Rayleigh scattering, enables a simultaneous determination of true gas-kinetic temperatures. Photodetector fatigue is avoided through a rotating mirror that serves as an optical shutter while individual gated integrators attached to each detector minimize the detection of background radiation from the plasma. The new instrument offers high stray-light rejection capability and provides measurements whose precision is photon-limited. Results obtained with the new instrument are presented in a companion paper.

Download or read book A New Procedure for Determination of Electron Temperatures and Electron Concentrations by Thomson Scattering and Analytical Plasmas written by Huang Mao and published by . This book was released on 1988 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new data-treatment procedure allows for more accurate determination of electron temperatures and electron concentrations in analytical plasmas. A Thomson scattering spectrum, useful for these determinations, is often not purely Gaussian in shape, even when the probed electrons possess a Maxwellian velocity distribution. Nonetheless, an unambiguous relationship exists between electron temperatures and concentrations that truly exist in a plasma and those calculated from a distorted Thompson scattering spectrum. Understanding this relationship permits a look-up table to be constructed, from which observed values can be corrected. Theory concerning this procedure is described and details for using it with both a ruby laser and frequency doubled Nd: YAG laser are discussed. Examples of electron temperature and electron concentration determined with this procedure in an ICP are given. The possibility of using the new procedure to study electron energy distributions is also assessed. Keywords: Thomson scattering; Inductively coupled plasma; Multielement analysis; Electron temperatures; Electron concentrations. (jhd).

Download or read book Government Reports Annual Index written by and published by . This book was released on 1988 with total page 1424 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 1988 with total page 1128 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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

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.

Download or read book Development of a Thomson Scattering Diagnostic on a Pulsed Power Machine and Its Use in Studying Laboratory Plasma Jets Focusing on the Effect of Current Polarity written by Jacob Thomas Banasek and published by . This book was released on 2019 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research primarily focused on the development of a collective Thomson scattering system for experiments on a 1~MA 100~ns pulsed power generator at Cornell University (COBRA). This diagnostic is capable of determining, at a minimum, the electron temperature, electron density and the flow velocity in the plasma. It was used in experiments on plasma jets created using a radial Al foil (thin disk of foil) load on COBRA. These jets served as a good load as they were long-lasting and at the center of the experimental chamber. The first set of experiments explored the rotation of the jet when an external magnetic field is applied and found the jet to be rotating at about 20~km/s. During these experiments, it was discovered that the Thomson scatter laser energy (10~J) was sufficient to heat the 20~eV jet plasma by inverse bremsstrahlung. While this did not affect the velocity measurements, it did significantly affect the measured temperature of the plasma. To better study this perturbation, a streak camera was set up to measure the changing temperature during the laser pulse. The plasma was found to be heated from about 20 to 80~eV in the first half of the laser pulse, before cooling down due to the expansion of the plasma. We also started developing a system to record the high-frequency Thomson scattering spectral feature to measure the density of the plasma. This showed some initial promising results and suggested densities of at least $5\times10^$~cm$^{-3}$. Finally, using low enough laser energy to avoid laser heating of the plasma, the effect of current polarity on the plasma jets was studied experimentally. It was found that while jets with a radial outward current flow were denser and wider than jets with a radial inward current, both jets had a similar electron temperature. These experiments were also compared to extended magnetohydrodynamic (XMHD) simulations. While experimental jets had about the same width as those in the simulation, they were found to be slightly colder and significantly less dense than the simulations.

Download or read book Thomson Scattering at FLASH Status Report written by and published by . This book was released on 2007 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The basic idea is to implement Thomson scattering with free electron laser (FEL) radiation at near-solid density plasmas as a diagnostic method which allows the determination of plasma temperatures and densities in the warm dense matter (WDM) regime (free electron density of n{sub e} = 1021-1026 cm−3 with temperatures of several eV). The WDM regime [1] at near-solid density (n{sub e} = 1021-1022 cm−3) is of special interest because, it is where the transition from an ideal plasma to a degenerate, strongly coupled plasma occurs. A systematic understanding of this largely unknown WDM domain is crucial for the modeling and understanding of contemporary plasma experiments, like laser shock-wave or Z-pinch experiments as well as for inertial confinement fusion (ICF) experiments as the plasma evolution follows its path through this domain.

Download or read book Handbook of Inductively Coupled Plasma Spectrometry written by Michael Thompson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first edition of our Handbook was written in 1983. In the preface to the first edition we noted the rapid development of inductively coupled plasma atomic emission spectrometry and its considerable potential for elemental analysis. The intervening five years have seen a substantial growth in ICP applications; much has happened and this is an appropriate time to present a revised edition. The basic approach of the book remains the same. This is a handbook, addressed to the user of the technique who seeks direct, practical advice. A concise summary of the technique is attempted. Detailed, theoretical treatment of the background to the method is not covered. We have, however, thoroughly revised much of the text, and new chapters have been added. These reflect the changes and progress in recent years. We are grateful to Mr Stephen Walton, Dr Gwendy Hall and London and Scandinavian Metallurgical Co. Ltd for their contributions. Chapter 3 (Instrumentation) has been rewritten by Mr Walton, the new Chapter on ICP-mass spectrometry has been written by Dr Hall, and London and Scandinavian provided much of the information for the chapter on metals analysis by ICP-AES. These chapters have been integrated into the book, and a conscious effort has been made to retain the unity of style within the book. New material has been added elsewhere in the book, archaeological materials are considered, pre concentration methods and chemometrics covered more fully.

Download or read book Investigation of Thomson Scattering from the Free Electrons in a Plasma written by Edward Rolfe and published by . This book was released on 1966 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: A plasma diagnostic technique is presented which utilizes the Thomson scattering of a laser beam from free electrons. By this means a measurement may be made of both electron concentration and temperature. An extensive analysis of background radiation (noise) is given, and of the photoionization effects of the laser beam. Details of a plasma source which continuously simulates conditions in a reentry plasma, of a giant pulse laser, and of detection apparatus are described. By taking advantage of the broad Doppler spectrum of the Thomson-scattered light, measurements of the spectral wings to the exclusion of the laser wavelength permits the elimination of background radiation to a substantial degree. The investigation is specialized to conditions encountered in reentry plasmas, but would be applicable to measurements in rocket exhausts and explosion generated plasmas. (Author).

Download or read book Electron Velocity Distribution Functions and Thomson Scattering written by Avram L. Milder and published by . This book was released on 2021 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Statistical mechanics governs the fundamental properties of many body systems and the corresponding velocity distributions dictates most material properties. In plasmas, a description through statistical mechanics is challenged by the fact that the movement of one electron effects many others through their Coulomb interactions, leading to collective motion. Although most of the research in plasma physics assumes equilibrium electron distribution functions, or small departures from a Maxwell-Boltzmann (Maxwellian) distribution, this is not a valid assumption in many situations. Deviations from a Maxwellian distribution can have significant ramifications on the interpretation of diagnostic signatures, and more importantly in our ability to understand the basic nature of plasmas. Optical collective Thomson scattering provides precise density and temperature measurements in numerous plasma-physics experiments. A statistically based, quantitative analysis of the errors in the measured electron density and temperature is presented when synthetic data calculated using a non-Maxwellian electron distribution function is fit assuming a Maxwellian electron distribution [A. L. Milder et al., Phys. Plasmas 26, 022711 (2019)]. In the specific case of super-Gaussian distributions, such analysis lead to errors of up to 50% in temperature and 30% in density. Including the proper family of non-Maxwellian electron distribution functions, as a fitting parameter, in Thomson-scattering analysis removes the model-dependent errors in the inferred parameters at minimal cost to the statistical uncertainty. This technique was used to determine the picosecond evolution of non-Maxwellian electron distribution functions in a laser-produced plasma using utrafast Thomson scattering [A. L. Milder et al., Phys. Rev. Lett. 124, 025001 (2020)]. During the laser heating, the distribution was measured to be approximately super-Gaussian due to inverse bremsstrahlung heating. After the heating laser turned off, collisional ionization caused further modification to the distribution function while increasing electron density and decreasing temperature. Electron distribution functions were determined using Vlasov-Fokker-Planck simulations including atomic kinetics. A novel technique that encodes the electron motion to the frequency of scattered light while using collective scattering to improve the scattering efficiency at velocities where the number of electrons are limited was invented to measure non-Maxwellian electron distributions [A. L. Milder et al., in review Phys. Rev. Lett. (2021)]. This angularly resolved Thomson-scattering technique is a novel extension of Thomson scattering, enabling the measurement of the electron velocity distribution function over many orders of magnitude. Electron velocity distribution functions driven by inverse bremsstrahlung heating were measured to be super-Gaussian in the bulk (v/vth 3) and Maxwellian in the tail (v/vth 3) when the laser heating rate dominated over the electron-electron thermalization rate. Simulations with the particle code Quartz showed the shape of the tail was dictated by the uniformity of the laser heating. The reduction of electrons at slow velocities resulted in a ? 40% measured reduction in inverse bremsstrahlung absorption. A reduced model describing the distribution function is given and used to perform a Monte Carlo analysis of the uncertainty in the measurements [A. L. Milder et al., in review Phys. Plasmas (2021)]. The electron density and temperature were determined to a precision of 12% and 21%, respectively, on average while all other parameters defining the distribution function were generally determined to better than 20%. It was found that these uncertainties were primarily due to limited signal to noise and instrumental effects. Distribution function measurements with this level of precision were sufficient to distinguish between Maxwellian and non-Maxwellian distribution functions"--Pages viii-x.

Download or read book On the Theory of Thomson Scattering and Reflectometry in a Relativistic Magnetized Plasma written by Henrik Bindslev and published by . This book was released on 1992 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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