new radiative shock experiments with high-power lasers

New radiative shock experiments

with high-power lasers

Francisco Suzuki-Vidal

Plasma Physics Group

Imperial College London

45th European Physics Society (EPS) Conference on Plasma Physics

2-6 July 2018, Prague, Czech Republic

Francisco Suzuki-Vidal ( f.suzuki @ imperial.ac.uk ) New experiments with radiative shocks (03/06/18)

(Dr) T. Clayson, G. Swadling, G. Burdiak, S.V. Lebedev

J. Foster, J. Skidmore,

P. Graham, C. Danson (et al.)

C. Spindloe

C. Stehlé, U. Chaulagain, R.L. Singh, J. Larour

R. Rodriguez, J.M Gil, G. Espinosa

M. Kozlová, M. Krůz,

J. Nejdl, J. Dostal (et al.)

P. Velarde, M. Cotelo

2

Acknowledgments

We are

here

Radiative shocks


Radiative shocks: Radiative energy flux > Kinetic energy flux

• Formed in hypersonic flows (~10 – 100’s km/s, M >> 1)

• Strong post-shock heating -> Strong radiative losses

Two main signatures (strongly dependent on opacity):

1) Radiation downstream: cooling -> increased compression

2) Radiation upstream: ionisation -> radiative precursor

High Energy Density Laboratory Astrophysics (HEDLA):

Space is a unique laboratory to study extreme plasma physics

3

Supernovae

(SN1987A

NASA, ESA) (HH901, HST)

Protostellar jetsAccretion columns

(Artist impression)

1

0

Shock transition

Radiative

zone

Distance

Pre-shock

(upstream)

Post-shock

(downstream)

1

4

𝜌

𝜌𝑝𝑟𝑒𝑠ℎ𝑜𝑐𝑘

𝑇

𝑇𝑝𝑜𝑠𝑡𝑠ℎ𝑜𝑐𝑘

𝑣

𝑣𝑠ℎ𝑜𝑐𝑘

1

0

100

Thermalized

zone

Hypersonic

M>>1

Subsonic

M<1

Adiabatic

compression

Increased

compression

Draine & McKee, Ann. Rev. Astron. Astrophys. (1993)

Budil et al., Astrophys. J. Supp. (2000)

Radiative

precursor

Radiative shocks


Supernova 1987A (NASA, ESA)

Accretion columnsSupernovae

(SN1987A

NASA, ESA) (Artist impression) (HH901, HST)

Protostellar jets

Radiative shocks can trigger the formation of

reverse radiative shocks

Requires a shock to collide with an obstacle

(solid or plasma)

Inertial Confinement Fusion (NIF laser)

(Pak et al., PoP 2013)

4

• High pressure, compressed D-T shell expanding into

in-falling low pressure plasma

• Radiative radiative shock moving at ~300 km/s

• 1-D rad-hydro simulations

Radiative shocks with high-power lasers

• Piston-driven radiative shocks: Laser ablation of a foil into gas (Xenon: maximise radiative effects)


• Omega laser (1-D shock tube)

600 m

m

Shocked Xe

shock tube

walls

(Kuranz, Drake et al. 2006)

5

Piston

(Be)

• LULI laser (3-D gas cell)

800 m

m

(Koenig et al., PoP 2006)Piston (CH)

Laser

probing

Radiative

precursor

Shocked Xe

(Van der Holst et al. 2013)

Simulations

(CRASH 2-D)

Aims of this work:

1. Simultaneously probe

the post-shock

and radiative

precursor

2. Produce

reverse radiative

shocks1-D shocks: Focused mostly on post-shock

3-D shocks: Focused mostly on radiatve precursor

Xenon

Electron

temperature


Radiative shocks with high-power lasers

Prague Asterix Laser System (PALS)

Czech RepublicOrion laser

AWE, UK

• Iodine laser

• ~1 shot / hour

• Shock drivers: 2 independent beams

(Total energy ~ 1k J, 350 ps)

• Intensity on target ~ 1015 W/cm2

• Largest long-pulse laser in UK

• ~5 shots / day

• Shock drivers: 10 long-pulse beams

(Total energy ~ 4 kJ, 1 ns)

• Intensity on target ~ 1015 W/cm2

Pictures courtesy of

AWE

6

comparable

Experiments on the Orion laser

1. Target design for reverse radiative shocks

2. Simultaneous post-shock and radiative precursor measurements

3. Numerical simulations

Francisco Suzuki-Vidal ( f.suzuki @ imperial.ac.uk ) New experiments with radiative shocks (03/06/18) 7


Orion: Target design

4 x Orion

drive beams

4 x Orion

drive beams

X-ray backlighting

2-D imaging

Optical self-emission

1-D streak

Gas-pressure

monitor

Optical laser

interferometry:

1-D streak

2-D imaging

(4 times)

~4 mm• Octogonal gas-cell: 8 mm diameter cross section << spot size (600 mm)

• Reverse shocks: Collision of two counter-propagating radiative shocks

Results in Xenon: F. Suzuki-Vidal et al., PRL 119, 055001 (2017)

Results in Neon: T. Clayson et al., HEDP 23, 60-72 (2017)

Target design: C. Spindloe et al., HPLSE 5, e22 (2017)

Radiative properties: R. Rodriguez et al., HPLSE 6, e36 (2018)

8

4 beams:

1.6 kJ, 1 ns

600 mm spot

Pistons

(25 mm CH +

50 mm CH-Br)

Static gas-fill

4 beams:

1.6 kJ, 1 ns

600 mm spot

Counter-

propagating

radiative

shocks

4 mm

8 mm

Orion: Post-shock in Xenon


Backlighter beams

~400 J, 500 ps

Backlighter foil

(Fe, V, Sc)

+ f20 mm pinhole

Image plate (Fuji BAS-TR)

Shock front

Fe backlighter (He-a, hn = 6.68 keV), Xe at ~0.3 bar (r0 = 1.65 mg/cc)

Shocks Collision Reverse

shocks

25 ns 30 ns 35 ns 40 ns

1.6 mm

Stagnation

• X-ray backlighting: Point-projection (~20 mm resolution),

time-resolved (500 ps), quasi-monochromatic (4 – 7 keV)

• X-ray absorption due to changes in mass density

9

shock and

post-shock

35 ns

Single drive

shock

Orion: Post-shock compression


Shock front velocity ~80 km/s

Position [mm]

Optical self-emission 1-D streak

Streak slit

10

X-ray absorption -> changes in mass density -> post-shock compression

Xenon:

Post-shock region

≲ 40 mm

(limit of XRBL

resolution)

Post-shock

(Xenon)

Piston

(CH-Br)

Neon:

Post-shock region

~50-80 mm

(better…)

Post-shock

(Neon)

Norm

aliz

ed inte

nsity 1

0.9

0.95

0.85

Model rps as a linear increase:

T. Clayson et al., HEDP (2017)

• Experimental XRBL and simulations result in

a post-shock compression ~ x 20-25

Left shock

Right shock

4 x r0Fit from data

Normalised

intensity

Orion: Radiative precursor


∫nedL

[cm-2]

24 ns22 ns20 ns18 ns

• X-ray backlighting: Shock and post-shock

11

Position [mm]

Heig

ht [m

m]

25 ns 30 ns 35 ns 40 ns

• Optical interferometry: Radiative precursor (same experiment)

Orion: Numerical simulations


2m

m

Mass density (8 – 36 ns)

Electron temperature

Re

flectiv

e b

ou

nd

ary

• 2-D axisymmetric simulations with rad-hydro codes NYM/PETRA (AWE)

• NYM: Early-time laser-piston interaction.

Lagrangian, multi-group implicit X-ray transport.

• PETRA: Late-time dynamics. Eulerian, multi-group X-ray diffusion, SESAME EoS,

2 mm resolution.

• Counter-propagating interaction simulated with fully-reflective boundary for hydro.

and radiation

12

Radiative

precursor

XeCH-Br

20 ns

Mass

density

Materials

Mixing / instabilities

at the interface

between

CH-Br and Xe

(~10 mm)

Orion: Reverse shock


Laboratory frame(ps = post-shock, prs = post-reverse shock)

Shocked material Stagnated material

Reverse

shock

𝜌𝑝𝑠 𝛒𝒑𝐫𝐬𝑣𝑝𝑠 𝑣𝑝𝑟𝑠 = 0

Re

fle

ctive

bo

un

da

ry

−𝑣𝑟𝑠

Te, 22 ns Te, 36 ns

𝑣𝑝𝑠 = 𝑣𝑠 1 −𝜌0𝜌𝑝𝑠

• Modified Rankine-Hugoniot relations for reverse

shock (Pak et al. 2013, Fortmann et al. 2012)

𝝆𝒑𝒓𝒔 = 1 +𝑣𝑝𝑠

𝑣𝑟𝑠𝜌𝑝𝑠

𝝆𝒑𝒓𝒔~ 100 𝜌0

13

Post-reverse shock density

Before collision:

After collision:

Known initial

conditionmeasured

estimated

measured

Experiments on the PALS laser

• XUV spectroscopy with Xe+He mixture

• 3-frame, fs interferometry



PALS: Target design

15

120 J, 350 ps

500 mm spot

10 mm CH

Piston 0.5 mm Au

(laser pre-heat

shield)

In-situ gas-fill

60 J, 350 ps

250 mm spot

~4 mm

Optical laser interferometry:

1-D streak (parallel or transverse)

XUV emission spectroscopy

Optical emission

spectroscopy

• Rectangular shock channel: 600 x 900 mm2 cross section (~spot size)

• Freedom to test new platforms!

• Asymmetric counter-propagating shocks

• New diagnostics

Experiments in Xenon: R.L. Singh et al., HEDP 23, 20-30 (2017)

Radiative-hydro simulations: M. Cotelo et al., HEDP 17, 68-73 (2015)

Spectroscopic analysis: R. Rodriguez et al., PRE 91, 053106 (2015)

4 mm


PALS: Shock and radiative precursor measurements

16

Time 4 mm

Drive lasers

hitting pistons

• Xenon fill at 0.1 bar (r0 = 0.6 mg/cc)

• 1-D optical streak interferometry (532 nm)

Dense shock

frontsRadiative

precursors

• Shock front position from probe cut-off ne > 1021 cm-3

(loss of fringes)

Shock front velocities ~ 55 km/s vs ~25 km/s

10 ns

20 ns

30 ns40 ns

Comparison with HELIOS 1-D

• Qualitative

agreement

only

(factor ~4

difference)

• Experimental

uncertainty on

precursor

shape

(departure

from 1-D?)

Measured electron density profiles

Piston Piston


PALS: XUV spectroscopy of Xe+He mixture

17

• Xenon + Helium mixture (90% -10%) at 0.6 bar (r0 = 3.3 mg/cc)

• He-lines to infer plasma temperature and density in post-shock

• Spatially- and time- integrated spectrometer…

18 20 22 24 26 28

Wavelength [nm]

90% Xe + 10% He

15 eV

Experimental resultsNumerical simulations

(ABAKO/RAPCAL)

• Observation of HeII lines requires T > 15 eV

• XUV spectra requires spatial and temporal resolution

R. Rodriguez et al.

• HeII lines present

• Xe VII – VIII lines observed

• O lines: heating of glass windows?


PALS: 3-frame, fs interferometry

18

• System developed by Institute of Plasma Physics and Laser Microfusion, Poland

• Shear interferometer, ~3 deg. angle between cameras

• 3 frames, 12 ns inter-frame, 150 fs exposure

T. Pisarcyk et al.

4 mm

0.9 mm

Pistons

Pre-shot image

Ti-Saph

l=810 nm

~1mJ

~150 fs exposure

4 ns

16 ns

28 ns

Future prospects



Radiative shocks: What’s next?

20

• Formation of ‘spikes’ in post-shock Neon and Argon (?)

ArgonNeonXenon

Hydrodynamic

instabilities..?

• Radiative shock experiments on the ShenGuang-II laser:

8 beams, 3 kJ, 1 ns + 9th beam for XRBL diagnostic

• First experiments: September 2018

SIOM

Shanghai

Imperial

College

London

SG-II laser

Summary

• New experiments to study radiative shocks on

Orion and PALS

• Orion: Simultaneous measurements of

post-shock and radiative precursor

• PALS: Test of new platforms

Gas mixtures, XUV spectroscopy, fs interferometry


Simulations of radiative shock in Neon

ARWEN code

2-D rad-hydro, AMR

(P. Velarde, UPM, Spain)

Mass density Velocity map

Electron temp. Materials

Thank you for your attention


new radiative shock experiments with high-power lasers

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