Probing matter at Gbar pressures at the NIF...temperature: - Fitting slope with LTE bremsstrahlung spectrum ~ exp(-hν/kT e): T e=400 eV- Fitting slope with Planck spectrum ~ ν3 exp(-hν/kT

02/10/14 | Dominik Kraus | NIF and JLF User Group Meeting 2014 | 1

Probing matter at Gbar pressures at the NIF

Dominik Kraus Department of Physics

University of California, Berkeley T. Doeppner, A. L. Kritcher, D. C. Swift, J. Hawreliak, D. Chapman, B. Bachmann,

P. M. Celliers, G. W. Collins, T. Darling, E. Dewald, J. Eggert, L. B. Fletcher, E. Foerster, D.O. Gericke, S.H. Glenzer, S. Hamel, R. Hemley, R. Jeanloz, O. L. Landen, H. J. Lee, S. LePape,

T. Ma, E. McKee, D. Milathianaki, J. Nilsen, P. Neumayer, R. Redmer, S. Rose, S. Rothman, C. Keane, and R. W. Falcone



Matter at Gbar pressure | Challenges and applications

ICF Plasmas at NIF!

Brown Dwarfs!

-  Interplay of Coulomb pressure and

electron-degeneracy pressure

-  Partial ionization, shell effects

-  Difficult description of compressibility and heat capacity

W. B. Hubbard et al, Physics of Plasmas 4, 2011 (1997)


Matter at Gbar pressure | Shell effects: heat capacity of aluminum

J. C. Pain, HEDP 3, 204 (2007)


Matter at Gbar pressure | Shell effects: Aluminum Hugoniot

J. C. Pain, HEDP 3, 204 (2007)


2 2.5 3 3.5 4 4.5 5

10−3

10−2

10−1

100

101

mass density [g/cm3]

pre

ssure

[G

bar]

SESAME #7592Cauble et al.Barrios et al.Ozaki et al.

Matter at Gbar pressure | CH Hugoniot & shell structure

PP0~ r−1


3.3-mm- diameter large LEH"

Solid CH or CD spheres with Ge preheat shield

Streaked Radiography"

X-ray Scattering"

Zn foil"9 kev line emission"

Au shield "

"Au Hohlraum"(5.75 x 9.42 mm)"Fill: 0.96 mg/cc "4He "

Modified existing NIF platform (1D Convergent Ablator) Main diagnostics: -  Streaked X-ray radiography

(shock speed, mass density)

-  X-ray Thomson scattering(electron temperature)

0

50

100

150

200

250

300

350

0

10

20

-2 0 2 4 6 8 10 12

Laser pulse shapes for F_Gbar_Gbar_AAA

inner (TW)

total (TW)

outer (TW)

Backlighter (TW)

La

se

r P

ow

er

(TW

)

Ba

ck

ligh

ter B

ea

ms

(TW

)

Time (ns)

Laser pulse shapes

Time (ns) Po

wer (T

W)

Experimental setup | X-ray radiography and scattering


Experimental setup | Target design

Zn backlighter foil

Au radiation shield

Rout = 1150 µm

CH (PaMS)

CH (GDP)

CH + 0.5% Ge

CH + 1% Ge

CH + 0.5% Ge

965 µm

capsule design with graded Ge dopant layer


Simulations | Parameter space

A. L. Kritcher et al., HEDP 10, 27 (2014)

Pressure at shock front


X-ray radiography | Raw data

N130701 N130103

'me

Self emission at 25.27±0.06 ns

January 03, 2013

July 01, 2013

radius (mm)

Time (ns)

6

4

8

10

2 0 0.5 0.5 1.0 1.0

N130701

22

20

24

26

18

Time (ns)

radius (mm) 0 0.5 0.5 1.0 1.0


X-ray radiography | Analysis

-  Profile matching to infer µ(r) = ρ(r) σ(r)

-  Movement of shock front with time gives shock velocity

-  After shock passes marker layer, enclosed mass between shock front and marker layer is known

-  Assuming constant density and constant opacity for first time step after passing marker layer: simultaneous density and opacity unfold

-  As shock propagates: Using relative comparison to the first time step after passing the marker layer gives full density and opacity profile

D. C. Swift et al., in prep.

shock front

Ge marker


X-ray radiography | Results

T. Doeppner et al., in prep.

Inferred opacity

Hugoniot data

2 2.5 3 3.5 4 4.5 5

10−3

10−2

10−1

100

101

mass density [g/cm3]

pre

ssure

[G

bar]

SESAME #7592, 24 KSESAME #7592, 298 KNIF (24 K)NIF (298 K)Cauble et al.Barrios et al.Ozaki et al.


X-ray scattering | Temperature measurement

-  X-rays are scattered from

plasma electrons

-  Elastic (Rayleigh): scattering from tightly bound electrons or free electrons which dynamically follow the ion motion

-  Inelastic (Compton): scattering from free or weakly bound electrons, mirrors electron velocity distribution ! Te


Calibration shot

Zn He-‐α

Cu He-‐α Cu He-‐β

Photon energy 7.4 keV 10 keV

Bragg crystal (HOPG)

(10° offset from DIM- axis) Debris shield

Mounts to gated detector

High-efficiency, gated x-ray spectrometer (7.4 – 10 keV)

Filter pack

X-ray scattering | Spectrometer setup

T. Doeppner et al., in prep.


X-ray scattering | Raw data

time-resolved x-ray spectrum

Kme

8.85 ns

X-‐ray ScaOering Signal

Photon energy

9.33 ns

Ungated Hard x-‐ray background

X-‐ray conKnuum emission

Zn source plasma and/or gold L-‐shell emission

streaked radiograph

space


8 8.5 9 9.50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Photon Energy [keV]

Sca

ttering in

tensi

ty

r=0.05mmr=0.1mmr=0.2mmr=0.3mmr=0.4mmr=0.5mm

X-ray scattering | Analysis: inhomogeneous sample

Different expected X-ray scattering spectra from different radii

0 200 400 600 800 10000

10

20

30

40

radius [µm]

mass

densi

ty [g/c

c]

mass density

0 200 400 600 800 10000

100

200

300

400

radius [µm]

ele

ctro

n tem

pera

ture

[eV

]

electron temperature


Kme

Kme

X-ray scattering | Analysis: scattering signal weighting

D. Chapman et al., in prep.

y [µm]

x [µm]

z [µm]

to spectrometer

9 keV radiaKon


Kme

Kme

Full analysis: -  Calculate radial

scattering spectrum for sample conditions

-  Apply weighting maps (3D)

-  Ray-tracing of weighted spectra to detector (3D)

-  Compare result with measured spectrum

X-ray scattering | Analysis: spectrometer ray-tracing

−8 −7 −6 −5 −4 −3 −2 −1 0 1−1

−0.5

0

0.5

1simulated detector image

x [mm]

y [m

m]

8600 8700 8800 8900 9000 9100 92000

0.2

0.4

0.6

0.8

1lineout

photon energy [eV]

inte

nsi

ty [

a.

u.]

point source1 mm spherical plasma


Kme

X-ray scattering | Results

8500 8600 8700 8800 8900 9000 9100 9200 93000

0.5

1

1.5

2

2.5

3

3.5

4x 10

5

photon energy [eV]

inte

nsi

ty

r < 0.12mmr < 0.20mmr < 0.30mmr < 0.40mmr < 0.50mmr < 0.60mmfull sample

8600 8700 8800 8900 9000 9100 92000

0.2

0.4

0.6

0.8

1

1.2

1.4

photon energy [eV]

inte

nsi

ty

measured spectrumcalculation

D. Kraus et al., in prep.

at r = 400 µm (Hydra + SESAME): Te = 60 eV ρ = 5.0 g/cm3 ZC = 3.9

Signal dominated by 300 µm ≤r ≤ 500 µm


X-ray scattering | Bremsstrahlung continuum

Photon energy

X-‐ray conKnuum emission

-  Slope sensitive to core plasma temperature:

-  Fitting slope with LTE bremsstrahlung spectrum ~ exp(-hν/kTe): Te=400 eV

-  Fitting slope with Planck spectrum

~ ν3 exp(-hν/kTe): Te=350 eV

0 200 400 600 800 10000

100

200

300

400

radius [µm]

ele

ctro

n tem

pera

ture

[eV

]

electron temperature

7700 7800 7900 8000 810010

7

108

photon energy [eV]

inte

nsi

ty [a. u.]

measured spectrumbremsstrahlung fit


CD targets | Hotspot ion temperature via DD fusion

We attempted CD experiment with no ablator

solid CD

CH

1150

µm

Capsule design: CD with a graded Ge doped ablator

Rout = 1150 µm

solid CD

CH

CH + 0.5% Ge

CH + 1% Ge

CH + 0.5% Ge 96

5 µm

solid CD

<1um RMS

Outgassing caused wrinkles



Au

CD CD

He LEH

DD Rate

Tion

DD ra

te [a. u.] T

rad [A. U.]

Laser P

ower [A

.U.]

Time (ns)

Hohlraum Component

2 8 4 6 0

Capsule Component



neutron Time-‐of-‐flight (ns)

PMT ou

tput (V

)

Preliminary

Hohlraum: Tion=6(2)keV Yield=1.29(10)e10

Capsule: Tion=0.5(1)keV Yield=0.1(1)e10

n-‐ToF Data 2-‐component Fit

§  neutron energy measured through time-of-flight over 18 m

§  neutron energy distribution is Doppler-broadened


Summary -  Developed and fielded an experimental platform for absolute Hugoniot

measurements up to the 1 Gbar regime -  Developed dedicated tools for data analysis for this very special and

demanding experimental geometry: -  Simultaneous density and opacity unfold of time resolved

radiography images -  3D analysis of X-ray Thomson scattering from inhomogeneous,

mm scale, multi-component dense plasma samples Posters M-15, T-10, T. Doeppner, D. Kraus

-  … -  First two Gbar equation of state experiments measured Hugoniot of

CH up to 720 Mbar Poster T-01, J. Hawreliak

-  Several approaches to experimentally constrain temperature: -  X-ray Thomson scattering (also sensitive to ionization state) -  DD fusion neutron yield -  X-ray self emission spectrum -  X-ray self emission absolute intensity Poster M-04, B. Bachmann


Outlook

-  Hugoniot measurements at lower pressure (connection to NOVA data)

-  Repeat of CD experiment

-  Further development of temperature diagnostics

-  Apply platform to different materials (HDC, …)

-  Development dedicated NIF platformfor X-ray Thomson scattering

Documents

Probing matter at Gbar pressures at the NIF...temperature: - Fitting slope with LTE bremsstrahlung spectrum ~ exp(-hν/kT e): T e=400 eV- Fitting slope with Planck spectrum ~ ν3 exp(-hν/kT