Download or read book 21nm X ray Laser Thomson Scattering of Laser heated Exploding Foil Plasmas written by and published by . This book was released on 2007 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent experiments were carried out on the Prague Asterix Laser System (PALS) towards the demonstration of a soft x-ray laser Thomson scattering diagnostic for a laser-produced exploding foil. The Thomson probe utilized the Ne-like zinc x-ray laser which was double-passed to deliver ≈1 mJ of focused energy at 21.2 nm wavelength and lasting ≈100 ps. The plasma under study was heated single-sided using a Gaussian 300-ps pulse of 438-nm light (3[omega] of the PALS iodine laser) at laser irradiances of 1013-1014 W cm−2. Electron densities of 102°-1022 cm−3 and electron temperatures from 200 to 500 eV were probed at 0.5 or 1 ns after the peak of the heating pulse during the foil plasma expansion. A flat-field 1200 line mm−1 variable-spaced grating spectrometer with a cooled charge-coupled device readout viewed the plasma in the forward direction at 30{sup o} with respect to the x-ray laser probe. We show results from plasmas generated from ≈1 [mu]m thick targets of Al and polypropylene (C3H6). Numerical simulations of the Thomson scattering cross-sections will be presented. These simulations show electron peaks in addition to a narrow ion feature due to collective (incoherent) Thomson scattering. The electron features are shifted from the frequency of the scattered radiation approximately by the electron plasma frequency ±[omega]{sub pe} and scale as n{sub e}12.

Download or read book New Regime of Thomson Scattering Probing Dense Plasmas with X Ray Lasers written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper the authors demonstrate through calculations and theoretical analysis the first application of a x-ray laser for probing hot, high-density plasmas (n[sub e][ge] 10[sup 23] cm[sup -3]) using a Ni-like transient collisional excitation x-ray laser as a probe. Theoretical predictions are used to diagnose the electron temperature in short pulse (500 fs) laser produced plasmas. The threshold power of the x-ray probe is estimated by comparing theoretical scattering levels with plasma thermal emission. The necessary spectral resolution of the instrument sufficient for resolving electron temperature is given.

Download or read book Soft X Ray Thomson Scattering in Warm Dense Hydrogen at FLASH written by and published by . This book was released on 2009 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present collective Thomson scattering with soft x-ray free electron laser radiation as a method to track the evolution of warm dense matter plasmas with ≈200 fs time resolution. In a pump-probe scheme an 800 nm laser heats a 20 [mu]m hydrogen droplet to the plasma state. After a variable time delay in the order of ps the plasma is probed by an x-ray ultra violet (XUV) pulse which scatters from the target and is recorded spectrally. Alternatively, in a self-Thomson scattering experiment, a single XUV pulse heats the target while a portion of its photons are being scattered probing the target. From such inelastic x-ray scattering spectra free electron temperature and density can be inferred giving insight on relaxation time scales in plasmas as well as the equation of state. We prove the feasibility of this method in the XUV range utilizing the free electron laser facility in Hamburg, FLASH. We recorded Thomson scattering spectra for hydrogen plasma, both in the self-scattering and in the pump-probe mode using optical laser heating.

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.

Download or read book Uv Thomson Scattering from X ray Laser Plasmas written by and published by . This book was released on 1991 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Interaction and Related Plasma Phenomena written by Heinrich Hora and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 1145 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 6th International Workshop in the series starting in 1969 was held at the Naval Postgraduate School in Monterey, California from 25-29 October, 1982 under the continuing directorship of Heinrich Hora. The co-directorship of the late Helmut Schwarz who helped found the series was assumed by George Miley. Fred Schwirzke served as the local organizer. Following a commemoration for Helmut Schwarz, Heinrich Hora connnented that the long title of the workshop is originally due to Nicholas Bloembergen, who prophetically envisaged that "related plasma phenomena" such as is involved in particle beam fusion is also of enormous interest to the laser connnunity. The en thusiastic response of the workshop advisors and the 82 participants from 11 countries supports the need for a continuation of this work shop-type meeting where an innnediate discussion and documentation of new results and conceptual formulations occurs, a process not possible through the usual journals. The main sponsor of this year's confer ence was the Fusion Studies Laboratory of the University of Illinois. Thanks are also due to the Naval Postgraduate School, Monterey, and the Department of Theoretical Physics, University of New South Wales. The conference was made feasible by the contributions of the partici pants, and they and their institutions deserve many thanks. Special recognition is due to the Conference Secretary, Chris Stalker (Urbana), as well as to Marie Wesson (Sydney) and to Patricia Vardaro (Monterey).

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 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:

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 Nonlinear Thomson Scattering of Intense Laser Pulse from Beams and Plasmas written by and published by . This book was released on 1993 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Comprehensive theory is developed to describe the nonlinear Thomson scattering of intense laser fields from beams and plasmas. This theory is valid for linearly or circularly polarized incident laser fields of arbitrary intensities and for electrons of arbitrary energies. Explicit expressions for the intensity distributions of the scattered radiation are calculated and numerically evaluated. The space-charge electrostatic potential, which is important in high density plasmas and prevents the axial drift of electrons, is included self-consistently. Various properties of the scattered radiation are examined, including the linewidth, angular distribution, and the behavior of the radiation spectra at ultrahigh intensities. Non-ideal effects, such as electron energy spread and beam emittance, are discussed. A laser synchrotron source (LSS), based on nonlinear Thomson scattering, may provide a practical method for generating tunable, near monochromatic, well collimated, short pulse x-rays in a compact, relatively inexpensive source. Two examples of possible LSS configurations are presented: an electron beam LSS generating hard (30 keV, 0.4 A) x-rays and a plasma LSS generating soft (0.3 keV, 40 A) x-rays. These LSS configurations are capable of generating ultrashort (approx. 1 ps) x-ray pulses with high peak flux (> 10(21) photons/s) and brightness (> 10(19) photons/s-mm2- mrad (2) 0.1% BW). Synchrotron radiation, Thomson scattering, Laser-plasma interactions.

Download or read book Ultra fast X ray Thomson Scattering Measurements of Coalescing Shock heated Matter written by and published by . This book was released on 2008 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The experiment in this work was preformed at the Titan laser facility (S1) where a short pulse beam at a wavelength of 1053nm delivered up to 350J in 0.5 to 20 ps and a long pulse beam at 527nm, 2[omega] frequency provided energies up to 450J in 1 to 6 ns. Long pulse shaping in this experiment, similar to future capabilities at NIF, was primarily a 4ns long foot with an intensity of 1 x 1013 W/cm2, followed by a 2ns long peak with an intensity of 3 x 1013 W/cm2. A ≈ 600 um phase plate was used on the long pulse beam to moderate non-uniformities in the intensity profile. An illustration of the Thomson scattering setup for this experiment is provided in Fig. 1 of the main text. A nearly mono-energetic scattering source of [Delta]E/E ≈ 0.3% in the 4.5 keV Ti K-alpha line was produced via intense short-pulse laser irradiation of 1.9 x 3 x 0.01 mm Ti foils, creating energetic keV electrons in the process (S2, S3). The nearly isotropic source emission (S4) is produced in the cold solid density bulk of the foil from electron K shell ionization of neutral or weakly ionized atoms, with an emission size on the order of the laser focal spot. By optimizing the laser intensity and pulse width to 4.4 x 1016 W cm−2, a total of 2.3 x 1013 x-ray photons have been produced into 4[pi]. This value corresponds to a conversion efficiency of laser energy into Ti K-alpha x-ray energy of 5 x 10−5, see Fig. S1. These sources provide ≈10 ps x-ray pulses as measured experimentally (S5).

Download or read book Thomson Scattering and Diamagnetic Loop Studies of a Relativistic Electron Beam heated Plasma written by John Dasho Sethian and published by . This book was released on 1976 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Use of Ultraviolet Thomson Scattering as a Versatile Diagnostic for Detailed Measurements of a Collisional Laser Produced Plasma written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Collective Thomson scattering from ion-acoustic waves at 266nm is used to obtain spatially resolved, two-dimensional electron density, sound speed, and radial drift profiles of a collisional laser plasma. An ultraviolet diagnostic wavelength minimizes the complicating effects of inverse bremsstrahlung and refractive turning in the coronal region of interest, where the electron densities approach n[sub c]/10. Laser plasmas of this type are important because they model some of the aspects of the plasmas found in high-gain laser-fusion pellets irradiated by long pulse widths where the laser light is absorbed mostly in the corona. The experimental results and LASNEX simulations agree within a percent standard deviation of 40% for the electron density and 50% for the sound speed and radial drift velocity. Thus it is shown that the hydrodynamics equations with classical coefficients and the numerical approximations in LASNEX are valid models of laser-heated, highly collisional plasmas. The versatility of Thomson scattering is expanded upon by extending existing theory with a Fokker-Planck based model to include plasmas that are characterized by (0 [le] k[sub ia][lambda][sub ii] [le] [infinity]) and ZT[sub e]/T[sub i], where k[sub ia] is the ion- acoustic wave number, [lambda][sub ii] is the ion-ion mean free path, Z is the ionization state of the plasma, and T[sub e], T[sub i] are the electron and ion temperatures in electron volts respectively. The model is valid for plasmas in which the electrons are approximately collisionless, (k[sub ia][lambda][sub ei], k[sub ia][lambda][sub ee] [ge] 1), and quasineutrality holds, ([alpha] [much-gt]1), where [alpha] = 1/k[lambda][sub DE] and [lambda][sub DE] is the electron Debye length. This newly developed model predicts the lineshape of the ion-acoustic Thomson spectra and when fit to experimental data provides a direct measurement of the relative thermal flow velocity between the electrons and ions.

Download or read book X ray Thomson Scattering from Dense Plasmas written by and published by . This book was released on 2007 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in the development of laser-produced x-ray sources have enabled a new class of high-energy density physics experiments. Powerful narrow-bandwidth x rays penetrate through short-lived hot dense states of matter and probe the physical properties with spectrally resolved x-ray scattering. Experiments from isochorically-heated plasmas with electron densities in the range of solid density and above have been demonstrated allowing for the first time exploration of the microscopic properties of dense matter regime close to strongly-coupled and Fermi degenerate conditions. Backscatter measurements have accessed the non-collective Compton scattering regime, which provides accurate diagnostic information on the temperature, density and ionization states. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions, quantum effects and detailed balance. In this talk, we will discuss new results important for applications of this technique for novel experiments in a wide range of research areas such as inertial confinement fusion, radiation-hydrodynamics, material science, and laboratory astrophysics.

Download or read book Thomson Scattering from Laser Plasmas written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thomson scattering has recently been introduced as a fundamental diagnostic of plasma conditions and basic physical processes in dense, inertial confinement fusion plasmas. Experiments at the Nova laser facility [E.M. Campbell et al., Laser Part. Beams 9, 209 (1991)] have demonstrated accurate temporally and spatially resolved characterization of densities, electron temperatures, and average ionization levels by simultaneously observing Thomson scattered light from ion acoustic and electron plasma (Langmuir) fluctuations. In addition, observations of fast and slow ion acous- tic waves in two-ion species plasmas have also allowed an independent measurement of the ion temperature. These results have motivated the application of Thomson scattering in closed-geometry inertial confinement fusion hohlraums to benchmark integrated radiation-hydrodynamic modeling of fusion plasmas. For this purpose a high energy 4[omega] probe laser was implemented recently allowing ultraviolet Thomson scattering at various locations in high-density gas-filled hohlraum plasmas. In partic- ular, the observation of steep electron temperature gradients indicates that electron thermal transport is inhibited in these gas-filled hohlraums. Hydrodynamic calcula- tions which include an exact treatment of large-scale magnetic fields are in agreement with these findings. Moreover, the Thomson scattering data clearly indicate axial stagnation in these hohlraums by showing a fast rise of the ion temperature. Its timing is in good agreement with calculations indicating that the stagnating plasma will not deteriorate the implosion of the fusion capsules in ignition experiments.

Download or read book X ray Emission from Colliding Laser Plasmas written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Colliding Au, CD and Ti-Cr plasmas have been generated by illuminating two opposing foils each with a [approximately] 100J, 0.5 nsec, 2[omega] Nd-glass laser beam from the Trident laser facility at Los Alamos. The plasmas are being used to study plasma interactions which span the parameter regime from interpenetrating to collisional stagnation. X-ray emission during the laser target interaction and the subsequent collision is used to diagnose the initial plasma conditions and the colliding plasma properties. X-ray instrumentation consists of a 100 ps gated x-ray pinhole imager, a time-integratcd bremsstrahlung x-ray spectrograph and a gated x-ray spectrograph used to record isoelectronic spectra from the Ti-Cr plasmas. The imager has obtained multi-frame images of the collision and therefore, a measure of the stagnation length which is a function of the ion charge state and density and a strong function of the electron temperature. Other instrumentation includes a Thomson scattering spectrometer with probe beam, neutron detectors used to monitor the CD coated foil collisions and an ion spectrometer. We will describe the current status of the experiments and current results with emphasis on the x-ray emission diagnostics. We will also briefly describe the modeling using Lasnex and ISIS, a particle-in-cell code with massless fluid electrons and inter particle (classical) collisions.

Download or read book Thomson Scattering of Ruby Laser Light by theta pinch Plasma written by H. J. Saleh and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: