Laser-plasma Interaction Generated Proton Isochoric Heating and Focusing PDF Download
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Author: Bingbing Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 282
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Book Description
Author: Bingbing Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 282
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
A new technique is described for the isochoric heating (i.e., heating at constant volume) of matter to high energy-density plasma states (>105 J/g) on a picosecond timescale (10−12 sec). An intense, collimated, ultrashort-pulse beam of protons--generated by a high-intensity laser pulse--is used to isochorically heat a solid density material to a temperature of several eV. The duration of heating is shorter than the timescale for significant hydrodynamic expansion to occur, hence the material is heated to a solid density warm dense plasma state. Using spherically-shaped laser targets a focused proton beam is produced and used to heat a smaller volume to over 20 eV. The technique described of ultrafast proton heating provides a unique method for creating isochorically heated high-energy density plasma states.
Author: J. King
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
It has recently been demonstrated that femtosecond-laser generated proton beams may be focused. These protons, following expansion of the Debye sheath, emit off the inner concave surface of hemispherical shell targets irradiated at their outer convex pole. The sheath normal expansion produces a rapidly converging proton beam. Such focused proton beams provide a new and powerful means to achieve isochoric heating to high temperatures. They are potentially important for measuring the equation of state of materials at high energy density and may provide an alternative route to fast ignition. We present the first results of proton focusing and heating experiments performed at the Petawatt power level at the Gekko XII Laser Facility at ILE Osaka Japan. Solid density Aluminum slabs are placed in the proton focal region at various lengths. The degree of proton focusing is measured via XUV imaging of Planckian emission of the heated zone. Simultaneous with the XUV measurement a streaked optical imaging technique, HISAK, gave temporal optical emission images of the focal region. Results indicate excellent coupling between the laser-proton conversion and subsequent heating.
Author: Shalom Eliezer
Publisher: CRC Press
ISBN: 084937605X
Category : Science
Languages : en
Pages : 293
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Book Description
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: J. Green
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) proposal to use this technique to initiate burn in a fusion capsule. Experiments designed to investigate electron isochoric heating have measured heating in two limiting cases of interest to fast ignition, small planar foils and hollow cones. Data from Cu K{alpha} fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256 eV are used to test PIC and Hybrid PIC modeling of the interaction. Isochoric heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a cone have been studied with the same diagnostic methods plus imaging of proton induced K{alpha}. Conversion efficiency to protons has also been measured and modeled. Conclusions from the proton and electron heating experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed.
Author: Dino A. Jaroszynski
Publisher: CRC Press
ISBN: 1584887796
Category : Science
Languages : en
Pages : 454
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Book Description
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: Herbie Lamar Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Particle acceleration from laser-plasma interactions has been a vibrant area of research since the discovery of electron and proton beams emitted from high intensity laser-plasma interactions in the 1980s. Since then, a large body of work has developed in pursuit of understanding and controlling the mechanisms that generate these particle beams, as well as the beams themselves. In particular, proton beams have a rich set of applications in the fields of medicine, fusion energy, and fundamental physics that motivates their study. In this thesis, we first discuss the laser technology that has enabled this research. We follow this with detailed information on the design and development of a 100 TW power upgrade to the graduate student-run GHOST laser system for the purposes of conducting repetition-rated laser-plasma experiments. We then outline the physics that drives particle acceleration during the interactions of high intensity lasers and solid targets with a particular focus on target normal sheath acceleration, the most widely studied laser-plasma particle acceleration mechanism. Finally, we describe experiments conducted on the Texas Petawatt Laser system to test an approach to enhance the yield, peak energy, and beam characteristics of proton beams generated by laser-plasma interactions with the use of focusing targets
Author: Thomas Sokollik
Publisher: Springer Science & Business Media
ISBN: 3642150403
Category : Science
Languages : en
Pages : 126
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Book Description
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.
Author: Helmut J. Schwarz
Publisher: Springer
ISBN: 1468409018
Category : Science
Languages : en
Pages : 510
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Book Description
Author: Teresa Jean Bartal
Publisher:
ISBN: 9781267288097
Category :
Languages : en
Pages : 133
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Book Description
Recent advances in generating high energy (> 50 MeV) protons from intense laser-matter interactions has opened up new areas of research, with applications in radiography, high energy density physics, and ion-proton beam fast ignition (FI). The ability to focus the proton beam has made these applications more attractive. Fast ignition (FI) is an evolved concept of conventional inertial confinement fusion (ICF). In proton FI, a collimated beam of protons is used to deliver the necessary ignition energy to the compressed Deuterium-Tritium (DT) fuel capsule instead of the original concept of a beam composed of relativistic electrons. In cone-guided FI, a cone is embedded into the side of the fuel capsule where the proton source foil is placed within the cone. The cone provides a clear path to the dense core and protects the proton source foil from radiation during the compression of the capsule. The proton source foil is a segment of a hemispherical shell target used to help focus the proton beam to the core to spark ignition. The viability of proton FI requires focusing of the generated proton beam to a 40 [mu]m spot at the compressed fuel and a laser to proton conversion efficiency of ~15%. Here, proton focusing and the laser to proton conversion efficiency are investigated using flat foils and hemispherical shell targets. Experiments were conducted on the 200 TW short pulse laser at Los Alamos Laboratory. The 1053 nm laser pulse delivered 70-80 J on target in 500-600 fs focused by an f/8 parabolic mirror. The generated proton beam from the target was examined by placing a mesh downstream of the target, which the proton beam would pass though and then imaged with a pack of radiochromic film (RCF). A 3D ray-tracing technique was developed to determine the focal position and focal spot size of the generated proton beam by tracing the proton trajectories from the image of the mesh collected by the RCF back through the mesh to the central axis. The focal position calculated from the ray-tracing technique for the flat foils resulted in a real focus, contrasting the convention wisdom of a virtual focus. Investigation of the proton expansion from flat foils established that initially the protons are accelerated normal to the surface, due to the fact that the electrostatic sheath field generated by the escaping hot electrons is only a few microns beyond the rear surface of the foil. As time progresses and more electrons are accelerated into the target by the laser irradiation, the sheath expands away from the rear surface of the foil, developing a bell-shaped curvature. The protons are then accelerated normal to the sheath field, which is at the leading edge of the expansion. Due to the bell-shaped curvature, protons that are accelerated further away from the central axis of the laser interaction experience gradients within the expansion causing the protons to gain radial velocity, which changes the angle of divergence of the protons. The radial velocity gained by the protons affects the trajectory of the protons, resulting in a calculated real focal position when trajectories are calculated the ray-tracing technique. The trajectories of the protons are further affected by the mounting technique. When the foils are mounted to washers for stability, electrons accelerated in the foil escaped into the washer creating a field along the interior wall of washer. The field affects the proton trajectories near the wall and decreases the laser to proton conversion efficiency. With the understanding gained from the flat foil targets, proton focusing is further investigated using freestanding hemispherical shell targets. Using the 3D ray-tracing technique, the calculated focal position is determined to be located inside the radius of curvature of the hemisphere, which is less than the distance of 1.7 R (where R is the radius of curvature of the hemispherical shell) determined from proton heating experiments. With the aid of particle-in-cell (PIC) simulations, using the code LSP (large-scale-plasma), it was determined that proton trajectories are not straight, but actually bend near the focal region. A hot electron pressure gradient in the expansion beam sets up a radial electric field, Er ~ kTehot/R, where here R is the radial scale length of the beam and kTehot is the hot electron temperature. When the radial electric field surpasses the radial acceleration force, the proton trajectories are bent away from the focal axis. The first demonstration of the generation and focusing of a proton beam from a hemispherical shell in a FI geometry is presented, where the beam is generated from a curved focusing surface, which propagates and is channeled via surface fields through an enclosed cone structure. A segment of a hemispherical shell is placed within a novel cone-shaped target. The proton focusing and conversion efficiency are calculated for the structured targets and are compared to the freestanding hemispherical shells. Particle-in-cell (PIC) simulations are presented for further understanding. It is clearly shown that the focusing is strongly affected by the electric fields in the beam in both open and enclosed (cone) geometries, bending the trajectories near the axis. It is also reported that in the cone geometry, a sheath electric field effectively channels the proton beam through the cone tip, substantially improving the focusing properties. The sheath electric field on the wall of the cone is generated by electrons that escape the hemispherical shell and travel into the surrounding structure. Focusing of the proton beam is improved by the sheath electric field on the wall of the cone; however, the laser to proton conversion efficiency is decreased due to the hot electrons escaping the shell reducing the amount of energy available to accelerate the protons.
