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
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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 1011J/m3.
• 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
Early universe
Quark/gluon mixtures
Hot NS
(T~1012 K, r~1012 cm-3)
(T~108
Cold NS
K, r~1014 cm-3)
TASK FORCE WORKING GROUPS
HEDP Task Force
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
THRUST AREAS IN HIGH ENERGY DENSITY
ASTROPHYSICS
HEDP Task Force
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?
THRUST AREAS IN HIGH ENERGY DENSITY
ASTROPHYSICS
HEDP Task Force
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?
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
simulation (Kifonidis et
al. 2000)
Type II SN shock
experiment (Robey
et al. 2001)
High Energy Density Plasma Science and Astrophysics
.
6 t = 1800 sec
Crab SNR (X-ray)
Supernova simulation
Jupiter
Supernova experiment
4
CH(Br)
2
120mm
0
Z
(1011
-4
cm)
Foam
Al pusher
00
D2
Liquid D2
100
100
Planar 2-mode RT, t = 13ns
Jet
shock front distance (mm)
Time (ns)
Au disk
0
0.0
Laser
beam
Extrasolar planets
1.0
2
2.0
3.0
4
4.0
5.0
time (ns)
Radius (RJ)
Lab relativistic micro-fireball jet
Mass (MJ)
distance (µm)
4
Hydrogen EOS experiment
Al
6
6.0
7.0
8.08
200
200
300
300
THRUST AREAS IN BEAM-INDUCED HIGH
ENERGY DENSITY PHYSICS
HEDP Task Force
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?
THRUST AREAS IN BEAM-INDUCED HIGH
ENERGY DENSITY SCIENCE
HEDP Task Force
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?
Facilities for Laser-Plasma and BeamPlasma Interactions Range from Very
Large to Tabletop Size
Laser wakefield acceleration
experiment in a gas jet
Plasma afterburner for
energy doubling
�
�
�
�
Double the energy of the collider with short plasma sections
before collision point.
1st half of beam excites the wake --decelerates to 0.
2nd half of beams rides the wake--accelerates to 2 x Eo.
Make up for Luminosity decrease N2/z2 by halving  in a
final plasma lens.
50 GeV
e-
LENSES
7m
P. Muggli
e+WFA
e-WFA
50 GeV
e+
IP
S. Lee et al., PRST-AB (2001)
U C L A
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 ~ 200-400 MeV (~ 2-4 x 1012 K).
U ~ 5-15 GeV/fm3 (~ 1030 J/cm3).
R ~ 10 fm, tlife ~ 10 fm/c (~3 x 10-23 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
cm
Background
plasma @ 10x
beam density
(not shown)
Ramped 220-390 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.
Initial
bunch length
•Beam intensity on target
increases by 50,000 X.
cm
Existing 3.9T solenoid focuses beam
•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 np>>nb, and Bz field [ Welch, Rose, Kaganovich].
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 eV @ 20J, 20 MeV
(Future US accelerator for HEDP)
Ion energy loss rate in targets
dE/dx
Aluminum
3 mm
x
3 mm
GSI: 40 GeV heavy Ions thick
targets Te ~ 1 eV per kJ
Dense, strongly coupled plasmas 10-2 to
10-1 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.
The Heavy Ion Fusion Science Virtual National Laboratory
Plasma plug and PPPL
volumetric RF plasma
source [Efthimion,
Gilson, et al., (2004)] .
18
Lead-Zirconium-Titanate ferroelectric
plasma source developed at PPPL
A 6 kV, 1 ms 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
The Lead-Zirconium-Titanate (PZT) ferroelectric plasma
source developed at PPPL can serve as an effective
plasma plug for charge neutralization
Neither plasma plug nor
volumetric plasma.
Plasma plug (PZT).
The Heavy Ion Fusion Science Virtual National Laboratory
20
1-m Barium Titanate Ferroelectric Plasma Source has
been developed and tested at High
PPPL
voltage lead
3 inches
19 cm long
test source
Vcharging = 6.5 kV
• Barium Titanate: er > 1000, stronger
than PZT, and contains no lead.
• Outer surface is metalized.
Ipeak = 1119 A
kT = 15 eV
n = 8  109 cm-3
Time exposure shows the sum of
• Inner electrode is a strip of perforated
steel sheet.
24 shots of the device.
Diagnostic access
1m
Neutralized Drift Compression Experiment (NDCX)*
Tiltcore
waveform
Beam current
diagnostic
*P. B. Roy et al., Physical
Review Letters 95, 238401
(2005).
The Heavy Ion Fusion Science Virtual National Laboratory
22
50-Fold Beam Compression achieved in Neutralized
Drift Compression Experiment at LBNL
Compression Ratio from Files 040505120632 and 120439 plotted 4/5/2005
Compression Ratio ratio
Compression
60
60
Intensity (au)
50
50
40
40
Phototube
30
30
20
20
10
10
0
4.92
0
Optical data
4.93
4.94
4.95
4.96
4.97
4.98
Time
(ns)
Time [microsec]
4.99
5.00
5.01
5.02
100
Coroborating data from
from PPPL Faraday cup
LSP simulation
0
The Heavy Ion Fusion Science Virtual National Laboratory
Time (ns)
100
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: np=1011cm-3; Beam:
Vb=0.2c, 48.0A, rb=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
HEDP Task Force
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.