Frontiers for Discovery in High Energy Density Physics Ronald C. Davidson Professor of Astrophysical Sciences Plasma Physics Laboratory Princeton University Presented to Dr. Robert Dimeo Acting Assistant Director for Physical Sciences Office of Science and Technology Policy Office of the President January 6, 2006

Recent National Studies on High Energy Density Physics Two recent national studies identified research opportunities of high intellectual value in high energy density plasma science. Studies were commissioned by: National Academies - National Research Council (Frontiers in High Energy Density Physics, - The X-Games of Contemporary Science National Academies Press, 2003). Office of Science and Technology Policy’s Interagency Working Group on the Physics of the Universe (National Task Force Report on High Energy Density Physics, July, 2004).

Scope of National Studies on High Energy Density Physics High energy density experiments span a wide range of physics areas including plasma physics, materials science and condensed matter physics, atomic and molecular physics, nuclear physics, fluid dynamics and magnetohydrodynamics, and astrophysics. While a number of scientific areas are represented in high energy density physics, many of the techniques have grown out of ongoing research in plasma science, astrophysics, beam physics, accelerator physics, magnetic fusion, inertial confinement fusion, and nuclear weapons research. The intellectual challenge of high energy density physics lies in the complexity and nonlinearity of the collective interaction processes.

Definition of High Energy Density The region of parameter space encompassed by the terminology ‘high energy density’ includes a wide variety of physical phenomena at energy densities exceeding J/m 3. In the figure, "High-Energy-Density" conditions lie in the shaded regions, above and to the right of the pressure contour labeled "P(total)=1 Mbar".

MAP OF THE HED UNIVERSE Hot NS (T~10 12 K, r~10 12 cm -3 ) Early universe Quark/gluon mixtures Cold NS (T~10 8 K, r~10 14 cm -3 )

TASK FORCE WORKING GROUPS A - HEDP in Astrophysical Systems Rosner (Chair), Arons, Baring, Lamb, Stone B - Beam-Induced HEDP (RHIC, heavy ion fusion, high-intensity accelerators, etc.) Joshi (Chair), Jacak, Logan, Mellisinos, Zajc S - HEDP in Stockpile Stewardship Facilities (Omega, Z, National Ignition Facility, etc.) Remington (Chair), Deeney, Hammer, Lee, Meyerhofer, Schneider, Silvera, Wilde U - Ultrafast, Ultraintense Laser Science Ditmire (Chair), DiMauro, Falcone, Hill, Mori, Murnane HEDP Task Force

THRUST AREAS IN HIGH ENERGY DENSITY ASTROPHYSICS Thrust Area #1 - Astrophysical phenomena What is the nature of matter and energy observed under extraordinary conditions in highly evolved stars and in their immediate surroundings, and how do matter and energy interact in such systems to produce the most energetic transient events in the universe? Thrust Area #2 - Fundamental physics of high energy density astrophysical phenomena What are the fundamental material properties of matter, and what is the nature of the fundamental interactions between matter and energy, under the extreme conditions encountered in high energy density astrophysics? HEDP Task Force

THRUST AREAS IN HIGH ENERGY DENSITY ASTROPHYSICS Thrust Area #3 - Laboratory astrophysics What are the limits to our ability to test astrophysical model and fundamental physics in the laboratory, and how can we use laboratory experiments to elucidate either fundamental physics or phenomenology of astrophysical systems that are as yet inaccessible to either theory or simulations? HEDP Task Force

Laboratory Astrophysics Motivating question: –What are the limits to our ability to test astrophysical models and fundamental physics in the laboratory; and how can we use laboratory experiments to elucidate either fundamental physics or phenomenology of astrophysical systems as yet inaccessible to either theory or simulations? The four key science objectives –Measuring material properties at high energy densities: equations of state, opacities, … –Building intuition for highly nonlinear astronomical phenomena, but under controlled lab conditions (with very different dimensionless parameters): radiation hydro, magnetohydrodynamics, particle acceleration, … –Connecting laboratory phenomena/physics directly to astrophysical phenomena/physics (viz., in asymptotic regimes for Re, Rm, …): late-time development of Type Ia and II supernovae, … –Validating instrumentation, diagnostics, simulation codes, …, aimed at astronomical observations/phenomena Type II SN shock experiment (Robey et al. 2001) Type II SN shock simulation (Kifonidis et al. 2000)

t = 1800 sec Z (10 11 cm) Supernova simulation CH(Br) Foam Supernova experiment 120  m Planar 2-mode RT, t = 13ns Jupiter Time (ns) Liquid D Hydrogen EOS experiment 0 Extrasolar planets Mass (M J ) Radius (R J ) distance (  m) Lab relativistic micro-fireball jet Jet Au disk Laser beam Crab SNR (X-ray) High Energy Density Plasma Science and Astrophysics

THRUST AREAS IN BEAM-INDUCED HIGH ENERGY DENSITY PHYSICS Thrust Area #4 - Heavy-ion-driven high energy density physics and fusion How can heavy ion beams be compressed to the high intensities required for creating high energy density matter and fusion ignition conditions? Thrust Area #5 - High energy density science with ultrarelativistic electron beams How can the ultra high electric fields in a beam-driven plasma wakefield be harnessed and sufficiently controlled to accelerate and focus high-quality, high-energy beams in compact devices? HEDP Task Force

THRUST AREAS IN BEAM-INDUCED HIGH ENERGY DENSITY SCIENCE Thrust Area #6 - Characterization of quark - gluon plasmas What is the nature of matter at the exceedingly high density and temperature characteristic of the Early Universe? Does the Quark Gluon plasma exhibit any of the properties of a classical plasma? HEDP Task Force

Facilities for Laser-Plasma and Beam- Plasma Interactions Range from Very Large to Tabletop Size Laser wakefield acceleration experiment in a gas jet

� Double the energy of the collider with short plasma sections before collision point. � 1 st half of beam excites the wake --decelerates to 0. � 2 nd half of beams rides the wake--accelerates to 2 x E o. � Make up for Luminosity decrease  N 2 /  z 2 by halving  in a final plasma lens. 50 GeV e - 50 GeV e + e - WFA e + WFA IP LENSES 7m Plasma afterburner for energy doubling S. Lee et al., PRST-AB (2001) U C L A P. Muggli

Physics of Quark - Gluon Plasmas Create high(est) energy density matter –Similar to that existing ~1 msec after the Big Bang. –Can study only in the lab – relics from Big Bang inaccessible. –T ~ MeV (~ 2-4 x K). - U ~ 5-15 GeV/fm 3 (~ J/cm 3 ). –R ~ 10 fm, t life ~ 10 fm/c (~3 x sec). Characterize the hot, dense medium –Expect quantum chromodynamic phase transition to quark gluon plasma. –Does medium behave as a plasma? coupling weak or strong? –What is the density, temperature, radiation rate, collision frequency, conductivity, opacity, Debye screening length? –Probes: passive (radiation) and those created in the collision.

Simulations demonstrate the possibility of dramatically larger compression and focusing of charge neutralized ion beams inside a plasma column Snapshots of a beam ion bunch at different times shown superimposed Velocity chirp amplifies beam power analogous to frequency chirp in CPA lasers. Solenoids and/or adiabatic plasma lens can focus compressed bunches in plasma. Instabilities may be controlled with n p >>n b, and B z field [ Welch, Rose, Kaganovich]. cm  Ramped keV K + ion beam injected into a 1.4-m - long plasma column: Axial compression 120 X. Radial compression to 1/e focal spot radius < 1 mm. Beam intensity on target increases by 50,000 X. Existing 3.9T solenoid focuses beam Background 10x beam density (not shown) Initial bunch length The Heavy Ion Fusion Science Virtual National Laboratory 16

Developed unique approach to ion-driven HEDP with much shorter ion pulses (< few ns versus a few ms) Maximum dE/dx and uniform heating at Bragg peak require short (< few ns) pulses to minimize hydro motion. [L. R. Grisham,PPPL (2004)].  Te > 10 20J, 20 MeV (Future US accelerator for HEDP) x Ion energy loss rate in targets dE/dx 3  m 3 mm GSI: 40 GeV heavy Ions  thick targets  Te ~ 1 eV per kJ Dense, strongly coupled plasmas to below solid density are potentially productive areas to test EOS models (Numbers are % disagreement in EOS models where there is little or no data) (Courtesy of Dick Lee, LLNL) The Heavy Ion Fusion Science Virtual National Laboratory 17

Measurements on the Neutralized Transport Experiment (NTX) at LBNL demonstrate achievement of smaller transverse spot size using volumetric plasma Neither plasma plug nor volumetric plasma. Plasma plug.Plasma plug and PPPL volumetric RF plasma source [Efthimion, Gilson, et al., (2004)]. The Heavy Ion Fusion Science Virtual National Laboratory 18

Lead-Zirconium-Titanate ferroelectric plasma source developed at PPPL A 6 kV, 1  s pulse applied across the inner and outer surfaces of a stack of high-dielectric cylinders produces, on the inner surface. A plasma then fills the interior volume [Efthimion, Gilson et al., (2005)]. The Heavy Ion Fusion Science Virtual National Laboratory 19

Neither plasma plug nor volumetric plasma. Plasma plug (PZT). The Lead-Zirconium-Titanate (PZT) ferroelectric plasma source developed at PPPL can serve as an effective plasma plug for charge neutralization The Heavy Ion Fusion Science Virtual National Laboratory 20

Barium Titanate:  r > 1000, stronger than PZT, and contains no lead. Outer surface is metalized. Inner electrode is a strip of perforated steel sheet. V charging = 6.5 kV I peak = 1119 A kT = 15 eV n = 8  10 9 cm -3 3 inches 19 cm long test source 1 m Diagnostic access High voltage lead Time exposure shows the sum of 24 shots of the device. 1-m Barium Titanate Ferroelectric Plasma Source has been developed and tested at PPPL

Neutralized Drift Compression Experiment (NDCX)* Tiltcore waveform Beam current diagnostic *P. B. Roy et al., Physical Review Letters 95, (2005). The Heavy Ion Fusion Science Virtual National Laboratory 22

50-Fold Beam Compression achieved in Neutralized Drift Compression Experiment at LBNL LSP simulation Coroborating data from from PPPL Faraday cup Optical data Phototube Intensity (au) Time (ns) Compression ratio Time (ns) The Heavy Ion Fusion Science Virtual National Laboratory 23

Analytical studies show that the solenoidal magnetic field influences the neutralization by background plasma Plots of electron charge density contours in (x,y) space, calculated in 2D slab geometry using the LSP code with parameters: Plasma: n p =10 11 cm -3 ; Beam: V b =0.2c, 48.0A, r b =2.85cm and pulse duration of 4.75 ns. A solenoidal magnetic field of 1014 G corresponds to  ce =  pe [Kaganovich, et al., (2005)]. In the presence of a solenoidal magnetic field, whistler waves are excited, which propagate at an angle with the beam velocity and can perturb the plasma ahead of the beam pulse. The Heavy Ion Fusion Science Virtual National Laboratory 24

CONCLUSIONS High energy density plasma science is a rapidly growing field with enormous potential for discovery in scientific and technological areas of high intellectual value. The opportunities for graduate student training, postdoctoral research, commercial spin-offs, and interdisciplinary research are likely to increase for many decades to come. HEDP Task Force