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Sources Of Hot Electrons In Laser Plasma Interaction With Emphasis On Raman And Turbulence Absorption
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Book Synopsis Sources of Hot Electrons in Laser-plasma Interaction with Emphasis on Raman and Turbulence Absorption by :
Download or read book Sources of Hot Electrons in Laser-plasma Interaction with Emphasis on Raman and Turbulence Absorption written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heating targets with high power lasers results in a sizable fraction of the absorbed energy going into electrons of temperature much greater than thermal which can pre-heat the pellet core and accelerate fast ion blowoff which results in poor momentum transfer and hence poor compression efficiency. The present emphasis is to build lasers of higher frequency, .omega.0, which at the same W/cm2 results in more absorption into cooler electrons. Two physical reasons are that the laser can propagate to a higher electron density, n, infinity.omega.02 resulting in more collisional inverse bremsstrahlung absorption proportional to n, and because the hot temperatures from some plasma absorption processes increase as the oscillatory velocity of an electron in the laser electric field v0/c = eE/(m/sub e/.omega.0). The heated electron temperatures from other plasma processes (Raman for example approx.(m/sub e//2)v2/sub phase/ and the higher laser frequency helps by increasing the competing collisional absorption and decreasing the Raman gain.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Exact Analysis of Hot Electrons Produced by Resonant Absorption in Laser-plasma Interaction by : Ravi Chandrasekar Venkatesan
Download or read book Exact Analysis of Hot Electrons Produced by Resonant Absorption in Laser-plasma Interaction written by Ravi Chandrasekar Venkatesan and published by . This book was released on 1988 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser-plasma Interactions and Hot Electron Generation in Inertial Confinement Fusion by : Jun Li
Download or read book Laser-plasma Interactions and Hot Electron Generation in Inertial Confinement Fusion written by Jun Li and published by . This book was released on 2016 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies several problems related to hot (energetic) electron generation in laser-plasma interactions in inertial confinement fusion (ICF). We study laserplasma instabilities (LPI) that can generate hot electrons in direct drive ICF under a range of laser intensities relevant to both the conventional hot-spot ignition and shock ignition. We study the in uence of LPI and hot electrons on the hydrodynamic evolution of ICF targets. We study hot electron generation in intense laser-plasma interactions in fast ignition cone targets. We also study how to implement particle collisions, which are important to hot electron generation in LPI, in Particle-in-Cell (PIC) codes on Graphic Process Units (GPU's). We find that ion density modulations can turn convective two-plasmon decay (TPD) and stimulated Raman scattering (SRS) instabilities to absolute ones in the region below the quarter critical density (nc=4). In this region, our uid simulations show that when a sinusoidal density modulation is superimposed on a linear density profile, convective two-plasmon decay (TPD) and stimulated Raman scattering (SRS) instabilities can become absolutely unstable under realistic direct-drive ICF conditions. Analysis of a three-wave model with a two-slope density profile shows that a sufficiently large change of the density gradient in a linear density profile can turn convective instabilities into absolute ones. An analytical expression is given for the threshold of the gradient change, which depends on the convective gain only. Growth rates for the absolute modes are also obtained. The threshold and growth rates from the two-slope profile are found to approximate those under sinusoidal modulations. These results explain the origin of the TPD modes below the nc=4 surface that in previous research were found to be critical to hot electron generation. Combining PIC and hydrodynamics simulations, we study the LPI and hydro evolution of coronal plasmas in an OMEGA EP[J.H. Kelly et al., 2006] long-scalelength experiment[Hu et al., 2013; Haberberger et al., 2014] with planar targets. Plasma and laser conditions are first obtained in a DRACO hydro simulation with only inverse-bremsstrahlung absorption. Using these conditions, an OSIRIS PIC simulation is performed to study laser absorption and hot-electron generation caused by LPI near the nc=4 region. The obtained information from the PIC simulation is subsequently coupled back to another DRACO simulation to examine how the LPI affect the overall hydrodynamics. The results show that the LPIinduced laser absorption can increase the electron temperature due to local heating by plasma waves. But it does not significantly change the density scale length in the corona because the high heat conductivity can spread the higher energy deposited near the nc=4 region in a wider region, and the portion of the energy carried by the hot electrons going towards high density region is still deposited beyond the nc=4 region. The collisional effects can affect the hot electron generation by damping the coupling waves of TPD and SRS instabilities. We have benchmarked the collision package in OSIRIS and adapted this package to a PIC code on graphics processors (GPU) with CUDA. The collision package is based on the cumulative collision theory, which treats a succession of small-angle binary collisions as a unique binary collision with a large scattering angle. It uses the computing cell in the GPUPIC code as the collision cell, and randomly pairs the particles in each collision cell for collision. In this process, it takes advantage of the fast on-chip shared memory and gets a remarkable performance. The benchmarks show that this collision package only needs to be called every 100 steps, and has a performance of 0:07 - 0:09ns=particle - step, only a 1:4% increase over the 5:36ns=particle - step without collisions on a Nvidia GTX 680 GPU. Test problems of beam-plasma scattering and electron plasma wave damping show that the collision frequencies calculated from the simulation results are consistent with theory. Hot electron generation is also important in fast ignition where typical laser intensities are higher than the hot-spot ignition or shock ignition. We perform PIC simulations for a cone-in-shell integrated fast-ignition experiment at the Omega Laser Facility[Boehly et al., 1997] with the initial plasma density profile taken from hydrodynamic simulations of the prepulse interaction with the gold cone. Hotelectron generation from laser-pre-plasma interactions and transport up to 100nc are studied. The simulations show a mean divergence half-angle of 68 degrees and 50% absorption for the hot electrons. The results show that the hot electrons are dominated in number by low-energy electrons but in energy by multi-MeV electrons. Electron transport between 5 and 100 nc is ballistic. In the late stage of the simulation, hot electron generation is largely independent of polarization, indicating a stochastic hot-electron-generation mechanism.
Download or read book Fusion Energy Update written by and published by . This book was released on 1980 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Proceedings of the Japan-U.S. Seminar on Theory and Application of Multiply-Ionized Plasmas Produced by Laser and Particle Beams, Nara Hotel, Nara, Japan, May 3-7, 1982 by : Chiyoe Yamanaka
Download or read book Proceedings of the Japan-U.S. Seminar on Theory and Application of Multiply-Ionized Plasmas Produced by Laser and Particle Beams, Nara Hotel, Nara, Japan, May 3-7, 1982 written by Chiyoe Yamanaka and published by . This book was released on 1982 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser Interaction and Related Plasma Phenomena by : Helmut J. Schwarz
Download or read book Laser Interaction and Related Plasma Phenomena written by Helmut J. Schwarz and published by Springer. This book was released on 2014-01-13 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book INIS Atomindex written by and published by . This book was released on 1985 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Plasma Wave Turbulence and Particle Heating Caused by Electron Beams, Radiation and Pinches by : Martin V. Goldman
Download or read book Plasma Wave Turbulence and Particle Heating Caused by Electron Beams, Radiation and Pinches written by Martin V. Goldman and published by . This book was released on 1979 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: For electron beams, a theory of the dynamics of driven Langmuir wave turbulence was developed. In low density beams, Langmuir wave evolution was found to be governed by nonlinear index of refraction effects, and associated self-focusing, rather than by wave reaction back on the beam. In laser-plasma interactions, the nonlinear theoretical work was verified experimentally in collaboration with Dr. N. Peacock of Culham Laboratories. In an experiment on nonlinear interactions of a carbon dioxide laser with a dense plasma focus device, almost 100 percent anomalous absorption of the radiation was observed along with intense Langmuir turbulence. The results were published in Physical Review Letters. A classical theory of the Raman-induced Kerr effect was developed. A computer code was developed to help determine plasma temperatures, radiation, impurity distributions, and overall plasma evolution in Z-pinch plasmas. (Author).
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1982 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Book Synopsis Study of Relativistic Electrons Generated from Ultra-intense Laser-plasma Interaction Relevant to Laser Wakefield Acceleration and Fast Ignition Laser Fusion by : Mianzhen Mo
Download or read book Study of Relativistic Electrons Generated from Ultra-intense Laser-plasma Interaction Relevant to Laser Wakefield Acceleration and Fast Ignition Laser Fusion written by Mianzhen Mo and published by . This book was released on 2015 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra-intense (> 10^18 W/cm^2) laser interaction with matter is capable of producing relativistic electrons which have a variety of applications in scientific and medical research. Knowledge of various aspects of these hot electrons is important in harnessing them for various applications. Of particular interest for this thesis is the investigation of hot electrons generated in the areas of Laser Wakefield Acceleration (LWFA) and Fast Ignition (FI). LWFA is a physical process in which electrons are accelerated by the strong longitudinal electrostatic fields that are formed inside the plasma cavities or wakes produced by the propagation of an ultra-intense laser pulse through an under-dense plasma. The accelerating E-fields inside the cavities are 1000 times higher than those of conventional particle accelerators and can accelerate electrons to the relativistic regime in a very short distance, on the order of a few millimeters. In addition, Betatron X-ray radiation can be produced from LWFA as a result of the transverse oscillations of the relativistic electrons inside the laser wakefield driven cavity. The pulse duration of Betatron radiation can be as short as a few femtoseconds, making it an ideal probe for measuring physical phenomena taking place on the time scale of femtoseconds. Experimental research on the electron acceleration of the LWFA has been conducted in this thesis and has led to the generation of mono-energetic electron bunches with peak energies ranging from a few hundreds of MeV to 1 GeV. In addition, the Betatron radiation emitted from LWFA was successfully characterized based on a technique of reflection off a grazing incidence mirror. Furthermore, we have developed a Betatron X-ray probe beamline based on the technique of K-shell absorption spectroscopy to directly measure the temporal evolution of the ionization states of warm dense aluminum. With this, we have achieved for the first time direct measurements of the ionization states of warm dense aluminum using Betatron X-ray radiation probing. Fast Ignition (FI) is an advanced scheme for inertial confinement fusion (ICF), in which the fuel ignition process is decoupled from its compression. Comparing with the conventional central hot-spot scheme for ICF, FI has the advantages of lower ignition threshold and higher gain. The success of FI relies on efficient energy coupling from the heating laser pulse to the hot electrons and subsequent transport of their energy to the compressed fuel. As a secondary part of this thesis, the transport of hot electrons in overdense plasma relevant to FI was studied. In particular, the effect of resistive layers within the target on the hot electron divergence and absorption was investigated. Experimental measurements were carried out and compared to simulations indicating minimal effect on the beam divergence but some attenuation through higher atomic number intermediate layers was observed.
Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Annual Index: Keyword A-L by :
Download or read book Government Reports Annual Index: Keyword A-L written by and published by . This book was released on 1985 with total page 976 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 1396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser-Driven Sources of High Energy Particles and Radiation by : Leonida Antonio Gizzi
Download or read book Laser-Driven Sources of High Energy Particles and Radiation written by Leonida Antonio Gizzi and published by Springer Nature. This book was released on 2019-09-05 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents a selection of articles based on inspiring lectures held at the “Capri” Advanced Summer School, an original event conceived and promoted by Leonida Antonio Gizzi and Ralph Assmann that focuses on novel schemes for plasma-based particle acceleration and radiation sources, and which brings together researchers from the conventional accelerator community and from the high-intensity laser-matter interaction research fields. Training in these fields is highly relevant for ultra-intense lasers and applications, which have enjoyed dramatic growth following the development of major European infrastructures like the Extreme Light Infrastructure (ELI) and the EuPRAXIA project. The articles preserve the tutorial character of the lectures and reflect the latest advances in their respective fields. The volume is mainly intended for PhD students and young researchers getting started in this area, but also for scientists from other fields who are interested in the latest developments. The content will also appeal to radiobiologists and medical physicists, as it includes contributions on potential applications of laser-based particle accelerators.
Book Synopsis On the Origin of Super-hot Electrons in Intense Laser-plasma Interactions by : Andrew G. Krygier
Download or read book On the Origin of Super-hot Electrons in Intense Laser-plasma Interactions written by Andrew G. Krygier and published by . This book was released on 2013 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis investigates the ultraintense laser-plasma interaction. An experiment to measure the generation of relativistic electrons and positrons was performed at the Texas Petawatt laser which resulted in the observation of the highest known positron energies ever recorded. The positrons are created by the Bethe-Heitler process where an electron scatters and emits bremsstrahlung radiation which then interacts with an atomic nucleus and creates an electron-positron pair. The positron bunch is a useful diagnostic for understanding the laser-plasma interaction. Modeling results are also presented that describe the acceleration mechanism for the highest energy electrons which drive many important applications. A simple mechanism we call loop-injected direct acceleration that is found to be overwhelmingly dominant in the acceleration of super-hot electrons is discussed in detail.
