Session 14HE: HEDP Theory and Experiments

Studies of High Energy Density Matter Using Intense Ion Beams: The HEDgeHOB Collaboration

Extensive theoretical work done over the past years that included sophisticated 2D and 3D numerical simulations as well as analytic modeling, has shown that intense heavy ion beams are an excellent tool for creating large samples of High Energy Density (HED) matter with fairly uniform physical conditions~[1]. It has been found that one may employ an ion beam using two very different experimental configurations that are named {\bf HIHEX}~[2,3] and {\bf LAPLAS}~[4,5]. The former scheme involves isochoric and uniform heating of matter by an ion beam that is followed by isentropic expansion of the heated material. Using this technique, one can access the entire phase diagram including those regions which can not be accessed by traditional methods of shock waves. The second scheme considers a multiple shock reflection technique that allows one to achieve a low-entropy compression of a test material like hydrogen or water which generates physical conditions that are expected to exist in the interior of giant planets. Interesting physical problems like Rayleigh-Taylor and Richtmyer-Meshkov instabilities have also been investigated in detail.This work has provided the necessary basis for the {\bf HEDgeHOB} scientific proposal for experiments at the Future Facility for Antiprotons and Ion Research [{\bf FAIR}], at Darmstadt. [1] N.A. Tahir et al., PRE 60 (1999) 4715. [2] D.H.H. Hoffmann et al., PoP 9 (2002) 3652. [3] N.A. Tahir et al., PRL 95 (2005) 035001. [4] N.A. Tahir et al., PRE 62 (2001) 016402. [5] A.R. Piriz et al., PRE 66 (2002) 056403.   

Monoenergetic Proton Radiography of Electromagnetic Fields in Laser-Plasma Interactions and Areal Density in Imploded Capsules$^{a,b}$

An isotropic, monoenergetic proton backlighter source with matched detector has been utilized on the OMEGA laser system to accurately and sensitively study the following: First, MG fields generated by laser plasma interactions $^{(1, 2)}$, both in the growth and decay phase, the latter associated with the development of 2-d symmetry breaking instabilities. Second, the reconnection of MG fields of interacting laser generated magnetic bubbles $^{(3)}$. Third, the fields and areal density evolution for cone-in-shell implosions $^{(4)}$. And fourth, the fields and areal density evolution of spherical implosions. Mottled, complex field structures are sometimes observed during the implosions. Because of the precise energy of the 14.7 (3.0) MeV P and 3.5 MeV alpha backlighter particles, a result of the fusion reaction of D and $^{3}$He (and DD) in an exploding pusher, a quantitative relationship can be established between particle energy loss and areal density (through stopping power) or between deflections and field strength (via the Lorentz force). Results of these experiments, as well as those currently being planned, such as accurate stopping power measurements in warm dense matter, will be presented. \newline a) In collaboration with scientists from MIT, LLNL, and LLE. \newline b) Supported by NLUF Contract DE-FG52-2005NA26011; and UR/FSC Contract 412761-G. \newline 1. C. K. Li et al, PRL \textbf{97} 2006~; 2. C. K. Li et al, PRL \textbf{99} 2007; 3. C. K. Li et al, PRL \textbf{99} 2007; 4. J. R. Rygg , submitted to Science.   

Recent progress of the HEDP research related to the astrophysics in China

The status of the HEDP research in China is reviewed, particularly of those related to the astrophysics studies. One of the two topics will be the confirmation of the atomic data critical when theoretical models are used to analyze the observed absorption spectra for astro-objects. Experiments were performed to measure the opacity of the SiO2 plasma generated by the Planckian radiation in gold hohlraum targets irradiated by high power laser pulses. Details of the contributions from different Si ions to the specific components of the absorption spectra were studied. This work is helpful in analysis of the Chandra observatory spectra. The other topic is related to the source of cosmic particles of high energy. The shock acceleration is believed to be the possible mechanism providing initial velocities of the charged particles around the supernovae before they obtain higher energy in Fermi acceleration process. PIC codes were used to simulate the collisionless electrostatic shock (CLES) waves driven by ultra-intense laser pulses. The formation conditions of the CLES, its propagations in plasma, and the details of the ion acceleration process by CLES were studied. Such topics are also important issues in the fast ignition scheme of the inertial confinement fusion.