LCLS
Plasm a and Warm Dense
Matter Studies
Richard W. Lee, L a w r e n c e L i v e r m o r e N a t i o n a l L a b o r a t o r y
P. A u d e b e r t, L a b o r a t o i r e p o u r l’Utilisation d e s L a s e r s I n t e n s e s ,
École Polytechnique Palaiseau, France
R.C. Cauble , L a w r e n c e L i v e r m o r e N a t i o n a l L a b o r a t o r y
J.-C. Gauthier, L a b o r a t o i r e p o u r l’Utilisation d e s L a s e r s I n t e n s e s,
École Polytechnique Palaiseau, France
O.L. Landen , L a w r e n c e L i v e r m o r e N a t i o n a l L a b o r a t o r y
C. Lewis, S c h o o l o f M a t h e m a t i c s a n d P h y s i c s , Q u e e n ’ s U n i v e r s i t y , B e l f a s t ,
Northern Ireland
A. Ng, Department of Physics and Astronomy, University of British Columbia, Canada
D. Riley, S c h o o l o f M a t h e m a t i c s a n d P h y s i c s , Q u e e n ’ s U n i v e r s i t y , B e l f a s t ,
Northern Ireland
S.J. Rose, C e n t r a l L a s e r F a c i l i t y , R u t h e r f o r d L a b o r a t o r y , C h i l t o n , O x f o r d s h i r e , U K
J.S. Wark , D e p a r t m e n t o f P h y s i c s , C l a r e n d o n L a b o r a t o r y , O x f o r d U n i v e r s i t y ,
Oxford, UK
The Importance of these States of Matter Derives from
their Wide Occurrence
•
Hot Dense Matter (HDM) occurs in:
• Supernova, stellar interiors,
accretion disks
• Plasma devices: laser
produced plasmas, Z-pinches
• Directly driven inertial fusion
plasma
•
Warm Dense Matter (WDM)
occurs in:
• Cores of large planets
• Systems that start solid and
end as a plasma
• X-ray driven inertial fusion
implosion
LCLS
Highlight of Three Experimental Areas in the High-Density
Finite-temperature Regime
•
LCLS
Creating WDM
• Generate
1 0 eV s o l i d d e n s i t y m a t t e r
• Measure the fundamental nature of the matter via equation of state
•
Probing resonances in HDM
• Measure kinetics process, redistribution rates, kinetic
models
•
Probing dense matter
• P e r f o r m , e.g . , s c a t t e r i n g f r o m s o l i d d e n s i t y m a t t e r
• M e a s u r e n e , T e , <Z>, f( v ) , a n d d a m p i n g r a t e s
LCLS,
Uniquely, Can Both Create and Probe High-density
Finite-temperature Matter
•
LCLS
To create WDM requires rapid uniform bulk heating
• High photon numbers, high photon energy, and short pulse length =>
high peak brightness
•
To pump/probe HDM requires an impulsive source of high energy photons
• Pump rate must be larger than competing rates
• No laser source has flux (laboratory x-ray lasers or otherwise)
•
To measure plasma-like properties requires short pulses with
signal > plasma emission
• No existing source can probe HDM or create WDM to probe
• 1 0 1 0 increase in peak brightness allows access to novel regimes
Theoretically the Difficulty with WDM is There are No Small
Parameters
LCLS
•
WDM is the regime where neither condensed matter (T = 0) methods nor
plasma theoretical methods are valid
•
The equation of state (EOS) of Cu indicates the problems
•
Thermodynamically consistent EOS based on numerous schemes has
proved impossible (attempted from 70’s)
•
A single incomplete description is now employed (from 1988)
In the WDM Regime Information Leads to New Results –
LCLS Will Be Unique Source of Data
•
Experimental data on D 2 along the
Hugoniot shows theories were and
are deficient
•
LCLS can heat matter rapidly and
uniformly to generate i s o c h o r e s
LCLS
Al ρ-T phase diagram
EOS’s along ρo Al isochore
LCLS
Experiment 1: Using the LCLS to Create WDM
•
For a 10x10x100 µm sample of Al
• Ensure the sample uniformly heated use 33% of beam energy
• Equating absorbed energy to total kinetic and ionization energy
E
V
•
•
=
3
2
n e Te
i
i
+ ∑ n i I p where I p = ionization potential of stage
i -1
i
G e n e r a t e a 1 0 eV solid density with n e = 2 x 1 0 2 2 c m - 3 a n d < Z > ~ 0 . 3
State of material on release can be measured with a short pulse
laser
• Estimated to be C s ~ 1.6x106 cm/s with pressure 4 Mb
• F o r 5 0 0 fs g e t s u r f a c e m o v e m e n t b y 8 0 Å
•
M a t e r i a l r a p i d l y a n d u n i f o r m l y h e a t e d r e l e a s e s isentropically
Experiment 2: LCLS Can Excite a Line Transition in HDM and
Provide Observable Results
•
'
For HDM the plasma collision rates and
spontaneous decay rates are large
LCLS
•
•
To effectively move population, pump
rate, R, must be > decay rate, A => R ≥ A
For I =
1014
W/cm2
R/A ~
10-4g
4
U /gLλ
• For LCLS
λ ~ 10 Å
R/A ~ 1
• For laboratory x-ray lasers
λ > 100 Å
Peak Spectral Brightness
(photons /s / mm 2/ mr2 / 0.1% bandwidth)
33
10
DESY
29
TTF – FEL
10
LCLS
Spontaneous
XRL
25
Laser plasmas
10
ESRF/APS 7 GeV
Undulator
ALS 1–2 GeV
21
Undulators
10
Wigglers
R/A << 1
APS 6-8 GeV
17
10
10–2
100
102
Photon Energy (keV)
LCLS Will Create Excitation Levels That Are
Observable in Emission
•
LCLS
Observe emission with
x-ray streak camera
Schematic experiment
CH
CH
25 µm Al
Al
Visible laser
LCLS tuned to 1869 eV
0.1 µm
• t = 0 laser irradiates Al dot
•
Simulations
3
2
1
1s3l
1s2l
1s 2
He-like
H-like
• t = 100 ps LCLS irradiates plasma
Experiment 3: LCLS Will Measure Properties of Solid Density
Finite Temperature Matter
LCLS
Scattering and absorption from solid Al
•
Scattering from free electrons
provides a measure of the Te, ne, f(v),
and plasma damping
• structure alone not sufficient for
plasma-like matter
•
Due to absorption, refraction and
reflection visible lasers can not probe
high density
• no high density data
•
LCLS scattering signals will be well
above noise for both WDM and HDM
Scattering of LCLS Will Provide Data on Free, Tightly-, and
Weakly-bound Electrons
LCLS
•
Weakly-bound and tightly-bound electrons depend on their binding
energy relative to the Compton energy shift
• Those with binding energies less than the Compton shift are
categorized weakly bound.
•
For a 25 eV, 4x10 23 cm-3 plasma the LCLS produces10 4 photons from
the free electron scattering
Goal for WDM Experiments at the LCLS: Measure EOS and
Plasma-like Properties
LCLS
• EOS measurements illuminate the microscopic
understanding of matter
• The state of ionization is extremely complex when
the plasma is correlated with the ionic structure
• Other properties of the system depend on the same
theoretical formulations
• For example, conductivity and opacity
Goal for HDM Experiments at the LCLS: Study Kinetics, Line
Shapes, and Plasma Formation
LCLS
• Since the advent of HDM laboratory plasma quantitative data
has been scarce
• The rapid evolution of high T e and ne matter requires a
short duration, high intensity, and high energy probe =>
LCLS
• The LCLS will permit measurements of:
• Kinetics behavior – rates, model construction
• Plasma coupling – direct measurement of S(k, λ)
• Line transition formation – line shapes, shifts, ionization
depression
• HED plasma formation – measure matter in the densest
regions