G. Penn

Ion beam heated target simulations for warm dense matter physics and inertial fusion energy

ION BEAM HEATED TARGET SIMULATIONS FOR WARM DENSE MATTER PHYSICS AND INERTIAL FUSION ENERGY J. J. Barnard 1 , J. Armijo 2 , D. S. Bailey 1 , A. Friedman 1 , F. M. Bieniosek 2 , E. Henestroza 2 , I. Kaganovich 3 , P. T. Leung 5 , B. G. Logan 2 , M.M. Marinak 1 , R. M. More 2 , S. F. Ng 2,5 , G. E. Penn 2 , L. J. Perkins 1 , S. Veitzer 4 , J. S. Wurtele 2 , S. S. Yu 2,5 , A. B. Zylstra 2 1. Lawrence Livermore National Laboratory, Livermore, CA 94550 USA 2. Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA 3. Princeton Plasma Physics Laboratory, Princeton, NJ 08543 USA 4. Tech-X Corporation, Boulder, CO 80303 USA 5. Chinese University Hong Kong, Hong Kong, China Abstract. Hydrodynamic simulations have been carried out using the multi-physics radiation hydrodynamics code HYDRA and the simplified one-dimensional hydrodynamics code DISH. We simulate possible targets for a near-term experiment at LBNL (the Neutralized Drift Compression Experiment, NDCX) and possible later experiments on a proposed facility (NDCX-II) for studies of warm dense matter and inertial fusion energy related beam-target coupling. Simulations of various target materials (including solids and foams) are presented. Experimental configurations include single pulse planar metallic solid and foam foils. Concepts for double-pulsed and ramped-energy pulses on cryogenic targets and foams have been simulated for exploring direct drive beam target coupling, and concepts and simulations for collapsing cylindrical and spherical bubbles to enhance temperature and pressure for warm dense matter studies *Work performed under the auspices of the U.S. Department of Energy under contract DE-AC52-07NA27344 at LLNL, and University of California contract DE-AC02- 05CH11231 at LBNL and contract DEFG0295ER40919 at PPPL. I. Introduction Heavy ion accelerators have long been advanced as drivers for inertial fusion energy (IFE), for their high efficiency, intrinsically high repetition rate, and their attractive final focus and chamber solutions. In a heavy ion fusion (HIF) driver, the final focus is accomplished using magnets (quadrupoles or solenoids) which can be shielded from the fusion microexplosions. The solid chamber wall can be shielded from the microexplosions using a flowing liquid salt, that acts as protection to the solid wall; an absorber of heat from the microexplosion; a heat transfer medium; and a breeder of the tritium component of the fuel. Because of high accelerator efficiency, both indirect drive targets and direct drive targets remain options for HIF. Indirect drive has relatively low intrinsic coupling efficiency (ratio of fuel kinetic energy to beam energy) because of the energy penalty in raising the temperature of the hohraum walls, but indirect drive targets

Spatially autoresonant stimulated Raman scattering in nonuniform plasmas

New solutions to the coupled three-wave equations in a nonuniform plasma medium are presented that include both space and time dependence of the waves. By including the dominant nonlinear frequency shift of the material wave, it is shown that if the driving waves are sufficiently strong in relation to the medium gradient, a nonlinearly phase-locked solution develops that is characteristic of autoresonance. In this case, the material electrostatic wave develops into a front starting at the linear resonance point and moving with the wave group velocity in a manner such that the intensity increases linearly with the propagation distance. The forms of the other two electromagnetic waves follow naturally from the Manley‐Rowe relations.

Highly Compressed Ion Beams for High Energy Density Science

The Heavy Ion Fusion Virtual National Laboratory is developing the intense ion beams needed to drive matter to the High Energy Density regimes required for Inertial Fusion Energy and other applications. An interim goal is a facility for Warm Dense Matter studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target “foils,” which may in fact be foams with mean densities 1% to 10% of solid. This approach complements that being pursued at GSI Darmstadt, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the beam requirements for Warm Dense Matter experiments. We discuss neutralized drift compression and final focus experiments and modeling. We describe suitable accelerator architectures based on Drift-Tube Linac, RF, single-gap, Ionization-Front Accelerator, and Pulse-Line Ion Accelerator concepts. The last of these is being pursued experimentally. Finally, we discuss plans toward a user facility for target experiments.

Heavy ion fusion science research for high energy density physics and fusion applications

Heavy ion fusion science research for high energy density physics and fusion applications* B G Logan 1 , J J Barnard 2 , F M Bieniosek 1 , R H Cohen 2 , J E Coleman 1 , R C Davidson 3 , P C Efthimion 3 , A Friedman 2 , E P Gilson 3 , W G Greenway 1 , L Grisham 3 , D P Grote 2 , E Henestroza 1 , D H H Hoffmann 4 , I D Kaganovich 3 , M Kireeff Covo 2 , J W Kwan 1 , K N LaFortune 2 , E P Lee 1 , M Leitner 1 , S M Lund 2 , A W Molvik 2 , P Ni 1 ,G E Penn 1 , L J Perkins 2 , H Qin 3 , P K Roy 1 , A B Sefkow 3 , P A Seidl 1 , W Sharp 2 E A Startsev 3 , D Varentsov 4 , J-L Vay 1 , W L Waldron 1 , J S Wurtele 1 , D Welch , G. A. Westenskow 1 and S S Yu 1 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Lawrence Livermore National Laboratory, Livermore, CA, 94551, USA Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA Gesellschaft fur Schwerionenforschung mbH, Darmstadt, Germany Voss Scientific, Albuquerque, NM, USA Corresponding Author’s E-mail: bglogan@lbl.gov Abstract During the past two years, the U.S. heavy ion fusion science program has made significant experimental and theoretical progress in simultaneous transverse and longitudinal beam compression, ion-beam-driven warm dense matter targets, high brightness beam transport, advanced theory and numerical simulations, and heavy ion target designs for fusion. First experiments combining radial and longitudinal compression of intense ion beams propagating through background plasma resulted in on-axis beam densities increased by 700X at the focal plane. With further improvements planned in 2007, these results will enable initial ion beam target experiments in warm dense matter to begin next year at LBNL. We are assessing how these new techniques apply to low-cost modular fusion drivers and higher-gain direct-drive targets for inertial fusion energy. 1. Introduction A coordinated heavy ion fusion science program by the Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and Princeton Plasma Physics Laboratory (the Heavy-Ion Fusion Science Virtual National Laboratory), together with collaborators at Voss Scientific and GSI, pursues research on compressing heavy ion beams towards the high intensities required for creating high energy density matter and fusion energy. Previously, experiments in the Neutralized Drift Compression Experiment (NDCX) and simulations showed increases in focused beam intensities first by transverse focusing [1, 2] and then by longitudinal compression (>50 X) with an induction buncher that imparts increasing ion velocities from the head to the tail of a selected 150 ns slice of beam [3, 4]. Section 2 describes new work on combined radial and longitudinal compression of intense beams within neutralizing plasma. In Section 3 we describe the first joint U.S.-German warm dense matter experiments with porous targets using intense beams from the SIS 18 storage ring at GSI [5], together with plans for initial warm dense matter targets at LBNL next year. Progress in e-cloud research is presented in Section 4, advances in theory and simulations in Section 5, applications to heavy ion fusion in Section 6, and conclusions in Section 7. 2. Combined transverse and longitudinal compression of beams within neutralizing plasma Recent experiments in NDCX have combined neutralized drift compression with a new final focusing solenoid (FFS) and a new target chamber (Figure 1). The FFS was installed with a new beam target chamber, and the plasma density was measured before installing on the NDCX beam line. Two Filtered Cathodic Arc Plasma Sources (FCAPS) streamed aluminum metal plasma upstream toward the exit of the FFS, and a Langmuir probe was driven from the upstream end of the FFS toward the focal plane of the magnet, 18.27 cm downstream of the midplane of the FFS. * This research was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Berkeley and Lawrence Livermore National Laboratories under Contract Numbers DE-AC02-05CH11231 and W-7405-Eng-48, and by the Princeton Plasma Physics Laboratory under Contract Number DE-AC02-76CH03073.

A plasma channel beam conditioner for a free electron laser

By conditioning an electron beam, through establishing a correlation between transverse action and energy within the beam, the performance of free electron lasers (FELs) can be dramatically improved. Under certain conditions, the FEL can perform as if the transverse emittances of the beam were substantially lower than the actual values. After a brief review of the benefits of beam conditioning, we present a method to generate this correlation through the use of a plasma channel. The strong transverse focusing produced by a plasma channel (chosen to have density 1016/cm3) allows the optimal correlation to be achieved in a reasonable length channel, of order 1 m. This appears to be a convenient and practical method for achieving conditioned beams, in comparison with other methods which require either a long beamline or multiple passes through some type of ring.

A Hilbert-Space Variational Principle for Spontaneous Wiggler and Synchrotron Radiation

Within the framework of Hilbert space theory, we have developed a maximum‐power variational principle applicable to classical spontaneous radiation from prescribed classical harmonic current sources. A simple proof is summarized for the case of three‐dimensional fields propagating in vacuum, and specialization to the case of paraxial optics is discussed. The techniques have been developed to model undulator radiation from relativistic electron beams (for which an example involving high harmonic generation is reviewed), but are more broadly applicable to synchrotron or other radiation problems, and may generalize to certain structured media.