Rainer Hörlein04/19/23

1ICUIL 2010

Watkins Glen

Femtosecond Probing of Solid Density Plasmas with Coherent High Harmonic

Radiation

Rainer Hörlein

Contributors

Rainer Hörlein04/19/23

ICUIL 2010Watkins Glen

2

LMU / MPQ:

Theory and Simulations:

• R. Hörlein•D. Kiefer• G. D. Tsakiris• F. Krausz

• S. Rykovanov• G. D. Tsakiris

Queens University Belfast, UK:

• B. Dromey• M. Zepf

• A. Henig• D. Jung• P. Heissler• D. Habs

Max-Born-Institute, Berlin, D:

• S.Steinke• T. Sokollik• M. Schnürer• P. Nickles• W. Sandner

Los Alamos Nat. Lab, USA:

• M. Hegelich• C. Gautier• R. Shah• S. Palaniyappan• S. Letzring• J. Fernandez• and the entire TRIDENT Team

Overview

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ICUIL 2010Watkins Glen

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1. Introduction

2. Dynamics of nm-Scale Foils

3. Plasma Probing using SHHG

4. Conclusions and Outlook

targetincident

beam

MCP-detector

collectionmirror

grating

entranceslit

1.1 Coherent Wake Emission

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ICUIL 2010Watkins Glen

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Plexiglass Target (Density ≈ 1.3 g/cm^3):Glass Target (Density ≈2.6 g/cm^3):

1113 121417 1516 1113 121415

1.2 Relativistic Harmonics

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Harmonic Spectra:Mirror Motion:

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1.3 Thin FoilsH

. George, et al., N

JP, 11, 113028 (2009)

U. Teubner, et al., PRL, 92, 185001, (2004).

K. Krushelnick, et al., PRL, 100, 125005, (2008).

Experiments:

CWE in transmission: ROM in transmission:

2. Dynamics of nm-Scale Foils

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nm-scale diamond-like carbon foils promise access to new regimes for efficient ion acceleration

S.G. Rykovanov et al., NJP. 10, 113005 (2008).O. Klimo et al., PR ST AB 11, 031301 (2008).

A.Henig et al., PRL 103, 245003 (2009)and many others

targetincident

beam

MCP-detector

collectionmirror

grating

entranceslit

X

Den

sity

2.1 The Berlin Laser System

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ICUIL 2010Watkins Glen

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5 µm FWHM

• Pulse energy 1.2 J (0.7 J with PM)• Pulse duration 40 fs• Rep. rate10 Hz• F/2.5 focusing• Adaptive mirror• Focused intensity 5x1019 Wcm-2

Laser focus

Berlin 30 TW CPA Ti:Sa system

Double Plasma – Mirror (DPM)

• energy throughput ~65%• contrast enhancement 103 to 104

• no decrease in focusability

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ICUIL 2010Watkins Glen

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2.2 Probing nm-Foil Targets

Harmonic Order

7 8 9 10 11 12

13 14

15

17 nm DLC

Harmonic Order

7 8 9 10 11 12

13 14

15

5 nm DLC

Harmonic Order

7 8 9 10 11 12

13 14

15

32 nm DLC

2.2 Probing nm-Foil Targets

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2D-PIC Simulation

a0=3.6, nmax=100nc, 25nm ramp, τ=10 cycles

Measured Density

Density during relativistic interaction

Consistent with 1D expansion of thefoil target ionized on the leading edge of the 45fs laser pulse

Cs,av≈2.2x107cm/sTExp ≈70fs

R. Hörlein et al., arXiv:1009.1582 (2010)

10th harmonic

x-position (microns)

y-po

siti

on (

mic

rons

)

10

-100 -50 0 50 100-20

0

20

40

60

80

100

120

140

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

50

-100 -50 0 50 100

-40

-20

0

20

40

60

80

100

120

0.93

0.94

0.95

0.96

0.97

0.98

0.99

50th harmonic

x-position (microns)

y-po

siti

on (

mic

rons

)

0 1 2 3 4 5 6 7 8 9 1010

20

30

40

50

60

70

80

90

100

position on detector [cm]

harm

onic

num

ber

ne = 400ncexp(-(r-20)2/42)

isotr source at -100 mdetector plane at 10 cm

test2.matxsimmax = 100;ysimmax = 100;Npoints = 1000; D = 100;

Position on detector (cm)

Har

mon

ic o

rder

3. Plasma Probing using SHHG

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harmonic target testplasma

incidentlaser

harmonicradiation

(very) preliminary Simulations

W. Theobald et al., PRL 77, 298 (1996).S. Dobosz et al., PRL 95, 025001 (2005).

previous work using gas harmonics for example:

hollow target100s of micron

harmonicsource

0 20 40 60 80 1000

100

200

300

400

radius (microns)

e- den

sity

(n c o

f w

0)

3.1 The TRIDENT Laser

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• Pulse energy 80 J•1 shot/45 min.

• F/3 focusing

TRIDENT short pulse beam:•Pulse duration 500 fs• Wavelength 1054 nm

• Adaptive mirror

• Focused intensity 5x1020 Wcm-2

TRIDENT has ~10x longer pulse than MBI but ~100x more pulse energy

i.e. 10x higher intensity on target

3.2 Relativistic Forward Harmonics

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Harmonic radiation from 200 nm DLC Targets

Harmonic Order

9 10 11 13 15

16 12 14 18 20 17 19 21

Normal incidence spectrometer Grazing incidence spectrometer

Harmonic Order

60 40 20

Rel

ativ

e In

tens

ity

10

1

0.1

n-3.5 scaling

n-2.0 scaling

n-2.75 scaling

3.3 Plasma Probing: First Results

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harmonic target probed foil

incidentlaser

residual laserand harmonics

Harmonic Order

60 40 20

Rel

ativ

e In

tens

ity

10

1

0.1

Density Information

200nm DLC200+80nm DLC

Conclusions and Outlook

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ICUIL 2010Watkins Glen

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• High harmonics generated on solid surfaces are a very versatile source of intense coherent XUV radiation

• High harmonics can be used to probe and monitor the interaction of intense femtosecond laser pulses with nm-scale foil targets

• Direct measurement of target density during relativistic interaction

• First clear observation of only odd-numbered relativistic harmonics in normal incidence geometry

• High harmonics generated with PW-scale short-pulse lasers could serve as unique backlighting sources for a wide range experiments