The Interaction of Ultraintense Laser Pulses with Solid Targets and Preformed Plasmas PDF Download

Author: M. Borghesi
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Languages : en
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Author: Romain Philippe Gaillard
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Languages : en
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Recent advances in laser and optical technologies have now enabled the current generation of high intensity, ultrashort-pulse lasers to achieve focal intensities of 102°-1021 W/cm2 in pulse durations of 100-500fs. These ultraintense laser pulses are capable of producing highly relativistic plasma states with densities, temperatures, and pressures rivaling those found in the interiors of stars and nuclear weapons. Utilizing the ultraintense 100TW JanUSP laser at LLNL we have explored the possibility of ion shock heating small micron-sized plasmas to extremely high energy densities approaching 1GJ/g on timescales of a few hundred femtoseconds. The JanUSP laser delivers 10 Joules of energy in a 100fs pulse in a near diffraction-limited beam, producing intensities on target of up to 1021W/cm2. The electric field of the laser at this intensity ionizes and accelerates electrons to relativistic MeV energies. The sudden ejection of electrons from the focal region produces tremendous electrostatic forces which in turn accelerate heavier ions to MeV energies. The predicted ion flux of 1 MJ/cm2 is sufficient to achieve thermal equilibrium conditions at high temperature in solid density targets. Our initial experiments were carried out at the available laser contrast of 10−7 (i.e. the contrast of the amplified spontaneous emission (ASE), and of the pre-pules produced in the regenerative amplifier). We used the nuclear photoactivation of Au-197 samples to measure the gamma production above 12MeV-corresponding to the threshold for the Au-197(y, n) reaction. Since the predominant mechanism for gamma production is through the bremsstrahlung emission of energetic electrons as they pass through the solid target we were able to infer a conversion yield of several percent of the incident laser energy into electrons with energies>12MeV. This result is consistent with the interaction of the main pulse with a large pre-formed plasma. The contrast of the laser was improved to the 10−1° level by the insertion of two additional pockel cells to reduce the pre-pulse intensities, and by the implementation of a pulse clean up technique based on adding an additional pre-amplifier and saturable absorber which resulted in a reduction in the ASE level by a factor of approximately 1000. In FY00/01 we performed a series of experiments to investigate the mechanisms for ion generation and acceleration in thin foil targets irradiated at incident laser intensities above 102° W/cm2, and with the laser contrast at 10−1°. Full details of this work can be found in the two accompanying papers: Energy spectrum and angular distribution of multi-MeV protons produced from ultraintense laser interactions, UCRL-JC-143112, P.K. Pate1 et al., and Enhancement of proton acceleration by hot electron re-circulation in thin foils irradiated by ultra-intense laser pulses, A.J. Mackinnon et al. UCRL-JC-145540. To obtain a more complete picture of the ion emission a range of detectors were developed and fielded including radiachromic films (measuring ion, electron, and x-ray dose), nuclear activation detectors (high energy protons), and single particle nuclear track detectors (protons and heavy ions). Significantly we found that a large fraction of the incident laser energy (greater than 1%) is coupled to highly energetic protons forming a well-collimated beam. The proton spectrum can be fit by an exponential distribution containing 1011 particles with a mean energy of 3 MeV and a high energy cutoff of 25 MeV. However, these particles appear to originate not from the interaction region at the front of the target but rather from a thin adsorption layer on the rear surface.

Author: National Research Council
Publisher: National Academies Press
ISBN: 030908637X
Category : Science
Languages : en
Pages : 177

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Recent scientific and technical advances have made it possible to create matter in the laboratory under conditions relevant to astrophysical systems such as supernovae and black holes. These advances will also benefit inertial confinement fusion research and the nation's nuclear weapon's program. The report describes the major research facilities on which such high energy density conditions can be achieved and lists a number of key scientific questions about high energy density physics that can be addressed by this research. Several recommendations are presented that would facilitate the development of a comprehensive strategy for realizing these research opportunities.

Author: Dimitri Batani
Publisher: Springer Science & Business Media
ISBN: 9780306466151
Category : Science
Languages : en
Pages : 434

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Proceedings of the 30th Course of the International School of Quantum Electronics on Atoms, Solids and Plasmas in Super-Intense Laser Fields, held 8-14 July, in Erice, Sicily

Author: Dimitri Batani
Publisher: Springer Science & Business Media
ISBN: 1461513510
Category : Science
Languages : en
Pages : 409

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The recent developement of high power lasers, delivering femtosecond pulses of 20 2 intensities up to 10 W/cm , has led to the discovery of new phenomena in laser interactions with matter. At these enormous laser intensities, atoms, and molecules are exposed to extreme conditions and new phenomena occur, such as the very rapid multi photon ionization of atomic systems, the emission by these systems of very high order harmonics of the exciting laser light, the Coulomb explosion of molecules, and the acceleration of electrons close to the velocity of light. These phenomena generate new behaviour of bulk matter in intense laser fields, with great potential for wide ranging applications which include the study of ultra-fast processes, the development of high-frequency lasers, and the investigation of the properties of plasmas and condensed matter under extreme conditions of temperature and pressure. In particular, the concept of the "fast ignitor" approach to inertial confinement fusion (ICF) has been proposed, which is based on the separation of the compression and the ignition phases in laser-driven ICF. The aim of this course on "Atom, Solids and Plasmas in Super-Intense Laser fields" was to bring together senior researchers and students in atomic and molecular physics, laser physics, condensed matter and plasma physics, in order to review recent developments in high-intensity laser-matter interactions. The course was held at the Ettore Majorana International Centre for Scientific Culture in Erice from July 8 to July 14,2000.

Author: Shalom Eliezer
Publisher: CRC Press
ISBN: 1420033387
Category : Science
Languages : en
Pages : 324

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The Interaction of High-Power Lasers with Plasmas provides a thorough self-contained discussion of the physical processes occurring in laser-plasma interactions, including a detailed review of the relevant plasma and laser physics. The book analyzes laser absorption and propagation, electron transport, and the relevant plasma waves in detail. It al

Author: Dino A. Jaroszynski
Publisher: CRC Press
ISBN: 1584887796
Category : Science
Languages : en
Pages : 454

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A Solid Compendium of Advanced Diagnostic and Simulation ToolsExploring the most exciting and topical areas in this field, Laser-Plasma Interactions focuses on the interaction of intense laser radiation with plasma. After discussing the basic theory of the interaction of intense electromagnetic radiation fields with matter, the book covers three ap

Author: Shalom Eliezer
Publisher: CRC Press
ISBN: 084937605X
Category : Science
Languages : en
Pages : 293

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Recent advances in the development of lasers with more energy, power, and brightness have opened up new possibilities for exciting applications. Applications of Laser-Plasma Interactions reviews the current status of high power laser applications. The book first explores the science and technology behind the ignition and burn of imploded fusion fue

Author: Thomas Sokollik
Publisher: Springer Science & Business Media
ISBN: 3642150403
Category : Science
Languages : en
Pages : 126

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Laser-driven proton beams are still in their infancy but already have some outstanding attributes compared to those produced in conventional accelerators. One such attribute is the typically low beam emittance. This allows excellent resolution in imaging applications like proton radiography. This thesis describes a novel imaging technique - the proton streak camera - that the author developed and first used to measure both the spatial and temporal evolution of ultra-strong electrical fields in laser-driven plasmas. Such investigations are of paramount importance for the understanding of laser-plasma interactions and, thus, for optimization of laser-driven particle acceleration. In particular, the present work investigated micrometer-sized spherical targets after laser irradiation. The confined geometry of plasmas and fields was found to influence the kinetic energy and spatial distribution of accelerated ions. This could be shown both in experimental radiography images and and in numerical simulations, one of which was selected for the cover page of Physical Review Letters.