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 RZ1: Mini-conference on Fast Ignition Status and Prospects III |
Hide Abstracts |
Chair: Riccardo Betti, University of Rochester Room: Adam's Mark Hotel Plaza Ballroom D |
Thursday, October 27, 2005 2:00PM - 2:40PM |
RZ1.00001: Overview of ultra-intense laser interactions with plasmas for fast ignition Kazuo A. Tanaka Ultra-intense laser interactions with plasmas play an important role in fast ignition experiments. The interactions will include stimulated Raman scattering and relativistic self-focusing. The level of SRS was measured to be 3{\%} at laser intensities mid. 10$^{18}$ W/cm$^{2}$ using 0.5 psec laser pulse. The detuning of plasma wave due to the relativistic effect is considered to interpret the level. The sensitivity of the refractive effect is measured using oblique incidence on pre-plasmas of self-focused ultra-intense laser light. Relativistic laser self-focusing has been proven to penetrate up to 10 critical density. This penetration mode could be used to help guiding the rest of the fast heating laser energy and this concept is introduced. Both gold cone and non-gold cone approaches may have several issues to be studied before introducing a 10 psec level pulse duration at a relativistic laser intensity which will be discussed at the talk. [Preview Abstract] |
Thursday, October 27, 2005 2:40PM - 3:00PM |
RZ1.00002: Ionization dynamics and associated heat transport in high power laser-matter interaction Yasuaki Kishimoto, Tomohiro Masaki Energy transport in high-Z solid materials irradiated by high power lasers is important to understand the complex dynamics realized in fast ignition based laser fusion target. So far, an ideal plasma state is usually assumed. However, the interaction and resulting energy transport process may be affected by atomic processes such as ionization and recombination. Here, we investigated the ionization dynamics in solid materials irradiated by intense laser pulse using a kinetic code including atomic and also relaxation processes. We found two types of prominent ionization dynamics, i.e. fast time scale avalanche-like propagation of ionization front due to induced plasma waves and subsequent slow time scale ionization. It is found that the ionization with slow time scale is tightly linked to non-local electron heat conduction process. Namely, high energy tail electrons which induce the heat transport via steep temperature gradient ionize the material to high charge states by electron impacts. We also observe ion accelerations in the solid due to thermal electric fields. [Preview Abstract] |
Thursday, October 27, 2005 3:00PM - 3:20PM |
RZ1.00003: Refraction of intense laser light with relativistic self-focusing in preformed plasma Hideaki Habara, K. Adumi, T. Yabuuchi, T. Tanimoto, J. Suzuki, T. Matsuoka, K. Kondo, R. Kodama, K. Tanaka We have studied propagation of an intense laser light in the preformed plasma. When the laser intensity is high enough, it is expected to change the laser propagation direction from the specular due to relativistic and nonlinear effect of laser light such as relativistic self-focusing. The experiments were performed using GMII 20TW laser system at ILE, Osaka Univ. The intense laser irradiate in the preformed plasma with 60 deg. incidence from the target normal. The incident and reflected light was observed by measuring the spatial distribution of accelerated fast electrons with a stack of imaging plates behind the side of the target. The size of IP is large enough to cover both incident and reflected directions. In the experiments, we observed two peaks on the imaging plate, each of which corresponds to the incident and reflected laser direction at the low energy shot. On the other hand, when the laser intensity increased, the peaks merge into one peak. It can be considered the reduction of the plasma refraction due to increase of gamma number by relativistic self-focusing. To evaluate the reflection angle, we performed a simple ray- trace calculation including relativistic self-focusing effect. The calculation indicates that the laser intensity increase about 8 times of the original laser intensity. The evolution of the refraction will be also discussed. [Preview Abstract] |
Thursday, October 27, 2005 3:20PM - 4:00PM |
RZ1.00004: Integrated Modeling of Short-Pulse Laser-Plasma Experiments R.P.J. Town, M. Chen, H. Chung, L.A. Cottrill, M. Foord, S.P. Hatchett, M.H. Key, A.B. Langdon, B.F. Lasinski, S. Lund, A.J. Mackinnon, B.C. McCandless, H.S. Park, P.K. Patel, B.A. Remington, R.A. Snavely, W.L. Sharp, C.H. Still, M. Tabak, D.R. Welch Modeling high energy density physics applications driven by short-pulse lasers requires the integration of many areas of physics that operate on disparate spatial and temporal scales. To perform such modeling in one integrated code would be computationally prohibitive, therefore we use the python scripting language to couple together independent hydrodynamics, explicit particle-in-cell (PIC) (Z3), implicit hybrid PIC (LSP), and atomic physics codes (FLYCHK) into one virtual code. This paper will briefly review the integration methodology and outline the new physics packages that have recently been added to LSP. We will contrast our simulation approach with those pursued by other researchers. We will present integrated simulation results of recent Petawatt K$\alpha $ radiography, electron transport, and isochoric heating experiments and show predictions of a proof-of-principle NIF fast ignition experiment. 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] |
Thursday, October 27, 2005 4:00PM - 4:20PM |
RZ1.00005: Theory and particle-in-cell modeling of laser acceleration of monoenergetic ion beams from layered targets B.J. Albright, L. Yin, B.M. Hegelich, K.J. Bowers, T.J.T. Kwan, J.C. Fern\'{a}ndez One possibility for achieving fast ignition inertial confinement fusion (ICF) involves the use of ion beams to ignite a compressed plasma to burning conditions, a scenario which is more effective for ion beams with small energy spread [Temporal, Honrubia, and Atzeni, Phys. Plasmas \textbf{9}, 3098 (2002)]. Recent experiments at the LANL Trident facility [Hegelich et al., submitted to Nature (2005)] have demonstrated that quasi-mono-energetic light ion beams with energies of several MeV/nucleon may be produced when a thin layer of light ions is accelerated from a heavy ion substrate in ultra-intense laser-matter experiments. In this presentation, the acceleration mechanism is examined within an analytical model and predictions are validated against particle-in-cell simulations and Trident data. Key dimensionless parameters controlling the beam dynamics are obtained, and implications and requirements for the feasibility of ion-driven fast ignition ICF will be discussed. [Preview Abstract] |
Thursday, October 27, 2005 4:20PM - 4:40PM |
RZ1.00006: Ion-driven fast ignition -- advantages and challenges Bjoern Manuel Hegelich, Brian J. Albright, Lin Yin, Juan C. Fernandez, Kirk A. Flippo Proton-driven fast ignition has been proposed as an alternate FI-scheme shortly after the discovery of high-current, high-energy laser-accelerated protons from the LLNL PW laser [1,2]. The demonstration of other laser-accelerated ion species [2], including mono-energetic light ions, has considerably increased the available parameter space in the search of the optimal FI-driver. The greatest disadvantage of any ion driver over the electron driver is the lower conversion efficiency of laser energy into \textit{beam particle} energy. This disadvantage may however be offset by more favorable stopping and transport characteristics, tipping the ratio of laser energy to \textit{deposited} energy in the fuel in favor of ion fast ignition. We will review these parameters, taking into account new results in laser-accelarated ions, target considerations and ion stopping in dense plasmas. We discuss how further progress can be made to exploit the advantages over electron fast ignition, such as increased stopping and stiffer beam characteristics. [1] M. Roth \textit{et al.}, PRL \textbf{86} (2001) 436 [2] Temporal \textit{et al.}, Phys. Plasmas \textbf{9} (2002) 3098 [3] Hegelich \textit{et al.}, submitted to Nature (2005) [Preview Abstract] |
Thursday, October 27, 2005 4:40PM - 5:00PM |
RZ1.00007: Generation of Ultrafast-Laser-Produced Heavy Ions for Fast Ignition Kirk Flippo, B.M. Hegelich, M.J. Schmitt, J.A. Cobble, D.C. Gautier, R. Gibson, R. Johnson, S. Letzring, J.C. Fern\'{a}ndez It has been pointed out that Fast Ignition (FI) is possible with a range of ion species [Temporal \textit{et. al} Phys. Plasma 2002], and there might be advantages in using ions heavier than protons. In the last few years it has become apparent that the surface contamination on laser-acceleration targets is a major impediment to the acceleration of the actual target ions. To this end we have performed experiments at the Los Alamos Trident Laser facility using a 150 ps pulse to ablatively clean targets before being irradiated by a 30 TW pulse to accelerate the bulk target ions to high energies. This process was used on targets consisting of 15 microns of vanadium. The 150 ps pulse rids the rear of the target of its omnipresent surface contamination layer, consisting mainly of water vapor and hydrocarbons, and allows the Trident TW Short-pulse arm to illuminate the target and accelerate ions via the Target Normal Sheath Acceleration (TNSA) mechanism. Normally, ions with the lightest charge to mass ratio (i.e. protons) would be accelerated preferentially; however with the contamination layer removed, the TNSA mechanism is able to accelerate the heavy target ions to high energies. The experimental achieved parameters, such as laser beam conversion efficiency, ion energy, and beam divergence are reported, and ablation results are compared to the LASNEX code. We also discuss future prospects to scale up this technique for FI. [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