Bulletin of the American Physical Society
2005 47th Annual Meeting of the Division of Plasma Physics
Monday–Friday, October 24–28, 2005; Denver, Colorado
Session KZ1: Mini-conference on Fast Ignition Status and Prospects I |
Hide Abstracts |
Chair: Kazuo Tanaka, ILE - University of Osaka Room: Adam's Mark Hotel Plaza Ballroom D |
Wednesday, October 26, 2005 9:30AM - 10:10AM |
KZ1.00001: Capsule optimization techniques for Fast Ignition* Max Tabak, Stephen Hatchett, Bruce Langdon, Mark Herrmann The general Fast Ignition scheme is well-known. Here we discuss two optimization techniques. In addition we will discuss strategies to ``sneak up'' on ignition with available drivers.The commonly discussed ignition method for Fast Ignition where heat is directly injected into the hotspot requires $\sim $5 times the hotspot energy as that associated with conventional implosions. This occurs because the fuel explodes during the run-up to ignition, wasting ignition energy on bulk fluid motion while the fuel density drops. We explore ``exploding pusher'' ignition schemes where a second implosion is driven by the injected energy. Early studies have shown that such a reimplosion can reduce the required ignition energy below the Atzeni scaling. Typical short pulse lasers deliver 20-30{\%} of their energy in a spot a few times the diffraction limit with the rest delivered in a spot 5-10 times that diameter. Survival of the final optic in energy applications will lead to large standoff requirements, large f/{\#}'s and hence spots. We describe the design of non-imaging collectors that can concentrate the incident laser light under a variety of scattering assumptions for a variety of incident illumination choices. *This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. [Preview Abstract] |
Wednesday, October 26, 2005 10:10AM - 10:30AM |
KZ1.00002: Potential for Accelerator-Driven Fast Ignition B. Grant Logan Critical issues and ion beam requirements are explored for fast ignition using ion beams to provide fuel compression using indirect drive and to provide separate short pulse ignition heating using direct drive. Several ion species with different hohlraum geometries are considered for both accelerator-produced and laser-produced ion ignition beams. Ion-driven fast ignition targets are projected to have modestly higher gains than with conventional heavy-ion fusion, and may offer some other advantages for target fabrication and for use of advanced fuels. However, much more analysis and experiments are needed before conclusions can be drawn regarding the feasibility for meeting the ion beam transverse and longitudinal emittances, focal spots, pulse lengths, and target stand-off distances required for ion-driven fast ignition. [Preview Abstract] |
Wednesday, October 26, 2005 10:30AM - 10:50AM |
KZ1.00003: Advanced concepts for fast-ignition from 2D ANTHEM modeling R.J. Mason The 2D implicit PIC/hybrid code ANTHEM has recently been used to model foil interactions with both steep and shallow density gradients, and fast-ignition cone-target experiments with super-compressed thermonuclear fuel cores. For these it has employed 1.06 $\mu $m picosecond laser intensities exceeding 4 x 10$^{19}$ W/cm$^{2}$ and core densities $\ge $ 10$^{25}$ electrons/cm$^{3}$. ANTHEM's mesh-following algorithm delivers laser energy to the critical surface, where it emits relativisitic electrons, which can be focused by the prevailing density and intensity profiles to deposit effectively more deeply. We shall show that heating of the core derives from conduction in from the blowoff cloud, ram and joule heating of the return currents, but mostly by the hot electron drag -- the range for which is a subject of present controversy. Core heating may be increased by design changes to bring higher hot electron densities to the core, such as a lightning rod cone tip, nested cone shells for vacuum insulation, and the use of shorter wavelength fast drivers to decrease the hot electron range. [Preview Abstract] |
Wednesday, October 26, 2005 10:50AM - 11:30AM |
KZ1.00004: Transport of Huge Currents of Charged Particles for Fast Ignition Applications Richard R. Freeman The Fast Ignition concept depends upon delivering enough energy to a compressed core of D-T for ignition from a psec-duration laser pulse. Even assuming that one has a peta-Watt class laser of sufficient energy, there is the problem that the laser pulse cannot penetrate the dense plasma surrounding the compressed core. That is, the light from the laser is stopped, with some, 30{\%} of the laser energy converted into fast electrons, at the relativistic critical density. From there, in order for these electrons to travel to the dense core and deposit their energy, they must travel through 4 orders of increasing density in a few tens of microns, while remaining tightly collimated. Recent experimental and theoretical work has demonstrated that the physics surrounding this propagation is both complex and surprisingly frustrating. In turns out that the experiments show that there are many anomalous stopping mechanisms that hinder this transport, and that the computer modeling for realistic targets is quite difficult. This talk outlines the difficulties, advances, and ``work-arounds'' that have been identified in the last several years. [Preview Abstract] |
Wednesday, October 26, 2005 11:30AM - 11:50AM |
KZ1.00005: Simulation of Weibel Electromagnetic Instability of Electron Beams in Plasma Using the Codes LSP and OSIRIS A. Solodov, C. Ren, J. Myatt, R. Betti, W.B. Mori The Weibel electromagnetic instability can prevent an efficient penetration of relativistic electron beams into the dense core of fast-ignition targets. We simulate the Weibel instability of a beam-plasma system\footnote{ R. Lee and M. Lampe, Phys. Rev. Lett. \textbf{31}, 1390 (1973).} with two particle-in-cell (PIC) codes: LSP and OSIRIS. While OSIRIS is an explicit PIC code, LSP, in addition to the explicit mode, also has an implicit mode, allowing simulations with a larger time step. This is particularly useful for very dense plasmas where the details of electron plasma oscillations can be ignored. LSP can also describe plasma electrons using either fluid or kinetic equations. The similarities and differences of the LSP and OSIRIS results will be discussed. This work has been supported by the U.S. DOE under Cooperative Agreements ER54789 and DE-FC03-92SF19460. [Preview Abstract] |
Wednesday, October 26, 2005 11:50AM - 12:10PM |
KZ1.00006: Experimental study on electron transport in high intensity laser solid interaction w/o cone Sophie Baton, P. Guillou, A. Benuzzi-Mounaix, J. Fuchs, M. Koenig, B. Loupias, D. Batani, A. Morace, D. Piazza, C. Rousseaux, R. Kodama, T. Norimatsu, M. Nakatsutsumi, Y. Aglitskiy New electron transport results have been obtained in the interaction of a high intensity laser with planar solid target w/o gold cone. The experiment has been performed at the LULI Laboratory with the 100 TW laser facility. The interaction took place either at 1.057 $\mu $m or at 0.53 $\mu $m wavelength. The targets consist of three layers planar targets molecularly bonded w/o gold cone glued on the front side. The target thickness and the surface size, the target holder, the ASE of the laser and its focalisation point have been varied in order to study their influence on the electron transport. Several diagnostics were implemented: visible rear side imaging, HISAC, X-ray-K$\alpha $ imaging and spectroscopy and the angular distribution of the emitted protons. In our conditions, no significant cone effect was observed. Nevertheless these results seem to indicate that the behaviour of the fast electrons is highly influenced by the target mass. [Preview Abstract] |
Wednesday, October 26, 2005 12:10PM - 12:30PM |
KZ1.00007: Instability of the ionization front during intense electron beam propagation through insulators S.I. Krasheninnikov, A.V. Kim, B.K. Frolov, R.B. Stephens Recent experimental investigations reveal a striking difference in the propagation of intense electron beams through metals and insulators. While in metals electron beam remains spatially uniform even after penetration through rather thick foil, the propagation of the beam through an insulator results in spatial filamentation of initially uniform beam and it happens at rather short distance from the surface of the foil. Both analytical and numerical analysis of intense electron beam propagation through an insulator show that in addition to binary ionization of neutrals, the electric field ionization process plays an important role in the neutralization of beam charge/current. Here we show that 1D ionization front in insulator is unstable. We identify long and short wavelength unstable modes both of which are associated with an impact of the electric field ionization process. We estimate the growth rate of these modes and compare our theoretical prediction with available experimental data. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700