Laser Plasma Interactions And Hot Electron Generation In Inertial Confinement Fusion
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Laser Plasma Interactions And Hot Electron Generation In Inertial Confinement Fusion
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Author : Jun Li
language : en
Publisher:
Release Date : 2016
Laser Plasma Interactions And Hot Electron Generation In Inertial Confinement Fusion written by Jun Li and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
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.
Laser Interaction And Related Plasma Phenomena
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Author : Helmut J. Schwarz
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Laser Interaction And Related Plasma Phenomena written by Helmut J. Schwarz and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Technology & Engineering categories.
The 7th International Workshop in the series LASER INTERACTION AND RELATED PLASMA PHENOMENA continued the high standards established by the earlier meetings in this series. It was organized under the directorship of Heinrich Hora and George H. Miley at the Naval Postgraduate School in Monterey, California, with Fred Schwirzke as the local organizer. These workshops have presented many "firsts" in laser plasma interactions and especially in laser fusion. Some presentations provided continuity with the past, most represented advancements; however, in some workshops, progress did not appear to be occurring as rapidly as in others. Therefore, it was a special pleasure that in the present workshop when, on October 30, 1985, Chiyoe Yamanaka disclosed a breakthrough in the generation of fusion neutrons with laser fusion targets. The 7th Workshop also continued to represent other new fields of laser-plasma interaction. The progress reported was most pronounced in the fields of X-ray lasers, laser acceleration of particles by electrostatic double layers in plasmas, and a particle beam technique to solve the geometric problem of muon-catalyzed fusion. The development of laser-plasma interactions at medium to high laser intensities may be seen in its whole complexity from a brief review of prior conferences. At the first Workshop in 1969, a comprehensive review of the field was presented by the speakers with the opening address by N.
Electron Generation And Transport In Intense Relativistic Laser Plasma Interactions Relevant To Fast Ignition Icf
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Author : Tammy Yee Wing Ma
language : en
Publisher:
Release Date : 2010
Electron Generation And Transport In Intense Relativistic Laser Plasma Interactions Relevant To Fast Ignition Icf written by Tammy Yee Wing Ma and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J.A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.
Electron Generation And Transport In Intense Relativistic Laser Plasma Interactions Relevant To Fast Ignition Icf
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Author :
language : en
Publisher:
Release Date : 2010
Electron Generation And Transport In Intense Relativistic Laser Plasma Interactions Relevant To Fast Ignition Icf written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J.A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.
Impact Of Pre Plasma On Electron Generation And Transport In Laser Plasma Interactions
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Author : Jonathan Lee Peebles
language : en
Publisher:
Release Date : 2017
Impact Of Pre Plasma On Electron Generation And Transport In Laser Plasma Interactions written by Jonathan Lee Peebles and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Relativistic laser plasma interactions in conjunction with an underdense pre-plasma have been shown to generate a two temperature component electron spectrum. The lower temperature component described by "ponderomotive scaling" is relatively well known and understood and is useful for applications such as the fast ignition inertial confinement fusion scheme. The higher energy electrons generated due to pre-plasma are denoted as "super-ponderomotive" electrons and facilitate interesting and useful applications. These include but are not limited to table top particle acceleration and generating high energy protons, x-rays and neutrons from secondary interactions. This dissertation describes experimental and particle-in-cell computational studies of the electron spectra produced from interactions between short pulse high intensity lasers and controlled pre-plasma conditions. Experiments were conducted at 3 laser labs: Texas Petawatt (University of Texas at Austin), Titan (Lawrence Livermore National Laboratory) and OMEGA-EP (University of Rochester). These lasers have different capabilities, and multiple experiments were carried out in order to fully understand super-ponderomotive electron generation and transport in the high intensity laser regime (I > 10^18 W/cm^2). In these experiments, an additional secondary long pulse beam was used to generate different scale lengths of "injected" pre-plasma while the pulse length and intensity of the short pulse beam were varied. The temperature and quantity of super-ponderomotive electrons were monitored with magnetic spectrometers and inferred via bremsstrahlung spectrometers while trajectory was estimated via Cu-K[alpha] imaging. The experimental and simulation data show that super-ponderomotive electrons require pulse lengths of at least 450 fs to be accelerated and that higher intensity interactions generate large magnetic fields which cause severe deflection of the super-ponderomotive electrons. Laser incidence angle is shown to be extremely important in determining hot electron trajectory. Longer pulse length data taken on OMEGA-EP and Titan showed that super-ponderomotive electrons could be created without the need for an initial pre-plasma due to the underdense plasma created during the high intensity interaction alone.
The Physics Of Inertial Fusion
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Author : Stefano Atzeni
language : en
Publisher: OUP Oxford
Release Date : 2004-06-03
The Physics Of Inertial Fusion written by Stefano Atzeni and has been published by OUP Oxford this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004-06-03 with Science categories.
This book is on inertial confinement fusion, an alternative way to produce electrical power from hydrogen fuel by using powerful lasers or particle beams. It involves the compression of tiny amounts (micrograms) of fuel to thousand times solid density and pressures otherwise existing only in the centre of stars. Thanks to advances in laser technology, it is now possible to produce such extreme states of matter in the laboratory. Recent developments have boosted laser intensities again with new possibilities for laser particle accelerators, laser nuclear physics, and fast ignition of fusion targets. This is a reference book for those working on beam plasma physics, be it in the context of fundamental research or applications to fusion energy or novel ultra-bright laser sources. The book combines quite different areas of physics: beam target interaction, dense plasmas, hydrodynamic implosion and instabilities, radiative energy transfer as well as fusion reactions. Particular attention is given to simple and useful modelling, including dimensional analysis and similarity solutions. Both authors have worked in this field for more than 20 years. They want to address in particular those teaching this topic to students and all those interested in understanding the technical basis.
Laser Interaction And Related Plasma Phenomena
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Author : Helmut J. Schwarz
language : en
Publisher: Springer
Release Date : 1971
Laser Interaction And Related Plasma Phenomena written by Helmut J. Schwarz and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with Science categories.
The 7th International Workshop in the series LASER INTERACTION AND RELATED PLASMA PHENOMENA continued the high standards established by the earlier meetings in this series. It was organized under the directorship of Heinrich Hora and George H. Miley at the Naval Postgraduate School in Monterey, California, with Fred Schwirzke as the local organizer. These workshops have presented many "firsts" in laser plasma interactions and especially in laser fusion. Some presentations provided continuity with the past, most represented advancements; however, in some workshops, progress did not appear to be occurring as rapidly as in others. Therefore, it was a special pleasure that in the present workshop when, on October 30, 1985, Chiyoe Yamanaka disclosed a breakthrough in the generation of fusion neutrons with laser fusion targets. The 7th Workshop also continued to represent other new fields of laser-plasma interaction. The progress reported was most pronounced in the fields of X-ray lasers, laser acceleration of particles by electrostatic double layers in plasmas, and a particle beam technique to solve the geometric problem of muon-catalyzed fusion. The development of laser-plasma interactions at medium to high laser intensities may be seen in its whole complexity from a brief review of prior conferences. At the first Workshop in 1969, a comprehensive review of the field was presented by the speakers with the opening address by N.
Laser Plasma Interactions 5
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Author : M. B. Hooper
language : en
Publisher: CRC Press
Release Date : 2019-10-01
Laser Plasma Interactions 5 written by M. B. Hooper and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-10-01 with Science categories.
This volume provides a broad overview in the increasingly important field of laser-plasma interactions. With the growth of research into fusion much international effort is being devoted to the problems of inertial confinement. This collection of lectures provides the novice researcher with the context in which current research papers can be understood. Laser Plasma Interactions 5 is one of the first publications to include recently declassified results from the United States inertial confinement fusion research program and as such is an indispensable reference for those wishing to find out about this previously inaccessible research. Presented by 14 speakers of international repute, the emphasis throughout the volume is on inertial confinement fusion. Topics also covered include plasma radiation and transport processes, diagnostic measurements, dense plasmas, high power lasers and X-ray lasers.
Laser Interaction And Related Plasma Phenomena
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Author : George H. Miley
language : en
Publisher: American Inst. of Physics
Release Date : 1998-04-15
Laser Interaction And Related Plasma Phenomena written by George H. Miley and has been published by American Inst. of Physics this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998-04-15 with Science categories.
The topics covered in the October 1993 Workshop are, as in the previous workshops, high-power and high-intensity laser generation and laser light interaction with matter; new fields opening up in laser-produced high-densit plasma research; unique new applications for such plasmas; and inertial confi
Two Plasmon Decay Mitigation In Direct Drive Inertial Confinement Fusion Experiments Using Multilayer Targets
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Author :
language : en
Publisher:
Release Date : 2016
Two Plasmon Decay Mitigation In Direct Drive Inertial Confinement Fusion Experiments Using Multilayer Targets written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Multilayer direct-drive inertial-confinement-fusion (ICF) targets are shown to significantly reduce two-plasmon-decay (TPD) driven hot-electron production while maintaining high hydrodynamic efficiency. Implosion experiments on the OMEGA Laser used targets with silicon layered between an inner beryllium and outer silicon-doped plastic ablator. A factor of five reduction in hot-electron generation (> 50 keV) was observed in the multilayer targets relative to pure CH targets. Three-dimensional simulations of the TPD driven hot-electron production using a laser-plasma interaction code (LPSE) that includes nonlinear and kinetic effects show excellent agreement with the measurements. As a result, the simulations suggest that the reduction in hot-electron production observed in the multilayer targets is primarily due to increased electron-ion collisional damping.