Acceleration and Characterization of Protons and Ions from Nanometer-Scale Thin Polymer Foil

Acceleration and Characterization of Protons and Ions

from Nanometer-Scale Thin Polymer Foil

Il Woo Choi

Center for Relativistic Laser Science, Institute for Basic Science (IBS)

Advanced Photonics Research Institute, Gwangju Institute of Science and Technology (GIST)

Korea

Ultrashort Quantum Beam Facility at GIST

2 2

Outline

PW laser and application facility at GIST

1

Ion acceleration using PW laser and ultrathin target

4

Ultrathin free-standing polymer target

3

Contrast enhancement and laser beam focusing

2

Conclusion

100 TW and PW Laser Systems, Interaction Target Chambers

Ultrashort PW laser system

Control room 100 TW laser-plasma laboratory X-ray generation target chamber Electron generation target chamber Ion generation target chamber Beam delivery vacuum tube Deformable mirror chamber PW laser-plasma laboratory

4 4 0 1 a   1 0  a

Gas, liquid, and solid target

(thickness : nm - mm – mm)

Radiations

(X-ray, THz, etc.)

Particles (electrons, protons, ions, etc.)

I > 1018 _W/cm2

t < ps Laser

beam

Interaction of Ultrashort Ultraintense Laser with Matter

Interaction of laser and matter in relativistic regime

2 1 0 1 / 2 0 _{w / c m} 0 D i m e n s i o n l e s s l a s e r a m p l i t u d e : 8 . 5 5 1 0 m e E a I m c m      

T. Tajima and G. Mourou, PRST-AB 5, 031301 (2002).

e c    _   _   v F E B

Opened up exotic research areas, such as the generation of ultrashort x-ray and particle sources, and the study on the high-field physics

Thin foil target Laser beam with

I ~1019 _W/cm2

Protons Electrons

Electric field

Strong electrostatic (space charge) field :

B e e B e D 4 M e V / m = T V / m k T E n k T e  m    

Hot electron propagation : MeV energy, mC-mC charge



Optimum thickness : several tens of nm - several

m

m, depending on the laser contrast,

pulse duration, and intensity.

Target Normal Sheath Acceleration (TNSA) and Optimum Thickness

D. Neely, APL 89, 021502(2006). M. Kaluza, PRL 93, 045003 (2004).

IL ~ 1019 W/cm2

Contrast : 1010

- Transverse spreading

- Surface deformation and density gradient - Recirculation and refluxing

6 6

Electron-proton mixture

Proton layer Electron layer Electrostatic

field Circular-polarized laser

with I > 1020 _W/cm2



Laser pulse pushes electrons forward and forms a high-density layer. A strong charge separation

force accelerates ions as a thin layer.



Ultrathin targets with nm-scale thickness

are necessary to balance the radiation pressure with

the restoring force given by the charge-separation field.

Radiation Pressure Acceleration (RPA) and Optimum Thickness

A. Henig, PRL 103, 245003 (2009).



= 0.8

m

m, I = 5×10

20

_W/cm

2

₍

_a

0

= 10.8 for c-pol. laser)

n

_e

= 200

n

_c

→

d

= 14 nm

Normalized areal density : e

c n d n    Optimal RPA condition :

0

Ti:Sapphire Laser Systems : LiFSA, PULSER

T. J. Yu et al., Opt. Express 20, 10807 (2012) ; J. H. Sung et al., Opt. Lett. 35, 3021 (2010).

30 fs, 34 J, 1.1 PW

PULSER I PULSER II LiFSA

LiFSA

(100 TW : Light source for Femto Science and Applications)

8 8

Spectral bandwidth : 46 nm (FWHM) Pulse duration : 30.2 ± 1.8 fs for 30 pulses

Temporal Pulse Profile and Contrast Ratio of PULSER II

Contrast ratio of 1.5 PW and 100 TW laser pulses measured using a third-order autocorrelation

2.3×10−12 at -500 ps 4.8×10−10 at -50 ps

100 TW 1.5 PW

There are several peaks observed before the main pulse at 220 ps, 170 ps, 63 ps, 35 ps,

and 25 ps. The prepulse, in the 100 TW laser pulse, with a contrast ration of 2.7 ×

10−10 at 220 ps is a ghost due to the effect of the third-order correlation between the main pulse and the post-pulse at 220 ps. A post pulse was generated from an AR-coated window with a thickness of 2 cm, which corresponded at 220 ps after the main pulse, in a vacuum beam expander. However, the prepulse at 170 ps is real, and we think that it is from the nonlinear interference between the main pulse and the post-pulse originating from the high-damage-threshold broadband polarizer (PBSK, CVI). The origins of the prepulses, in the 100 TW laser pulse, at 63 ps, 35 ps, and 25 ps are currently under investigation.

We think the contrast ratio for 1.5 PW pulses would be worse than that for 100 TW pulses in the range over 300 ps when considering the energy increase in the booster amplifier. However, because of the instrument detection limit, it is hard to compare contrast ratios between 1.5 PW pulses and 100 TW pulses. We could not observe any serious degradation in the contrast ratio for 1.5 PW pulses less than less than 300 ps. The reason is that the gain of ASE inside the stretched pulse was similar to the gain experienced by the main pulse.

Pulse width after compressor 44.5 J, 30.2 fs → 1.5 PW

Insufficient for ultrathin target

P. Gibbon, Nature Physics 3, 369 (2007).

Contrast Enhancement Needed with Plasma Mirror

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 M a xim u m p ro to n e n e rg y ( M e V ) Target position (mm) no pr oto n s

Contrast enhancement with one plasma mirror : ~100

10 10

Double Plasma Mirror (DPM) System for 100 TW Laser Pulse

0 100 200 300 400 500 0.2 0.3 0.4 0.5 0.6 (125,0.52) (406,0.59) (125,0.42) Re flectivity Energy fluence

(

J/cm2

)

Plasma mirror system

Plasma mirror

(406,0.48)

Large area DPM and precise pre-alignment allows

repetitive operation.

• Spatial beam profile of the focused laser after DPM system for the energy fluence of (a) 90 J/cm2

and (b) 290 J/cm2_{. The insets show the focused image for these energy fluencies respectively}

• 2-dimensional Normalized Standard Deviation distribution of near field for 15 laser shots with and without DPM. (a) without DPM, (b) for 90 J/cm2 _{with DPM, (c) for 290 J/cm}2 _{with DPM.}

Spatial Characteristics of Laser Beam Profile from DPM

stable stable _unstable

-200 -100 0 100 200 0 20 40 60 80 100 120 140 160 (b) Horizontal Vertical Distance (mm) In tensity (ar b. u ni ts) -200 -100 0 100 200 0 50 100 150 200 250 300 Distance (mm) In tensity (arb. u ni ts) Horizontal Vertical (a) 400 500 600 400 500 600 400 500 600 400 500 600

12 12 Double plasma mirror OAP OAP 45o _mirror 45o _mirror Half-wave plate Half-wave plate 1580 mm 2740 mm

Incident laser from PW pulse compressor

To target chamber

200 mm

f = 2 m, 20° off-axis angle

Double Plasma Mirror System for PW Laser Pulse

~350 shots available for ~100 J/cm2

Repetitive operation

is possible by large area DPM and precise pre-alignemnt.

13 13

Temporal Contrast Ratio after PW Double Plasma Mirrors

Advantages when using a plasma mirror

- Contrast enhancement : ~10

4

-

< 3

×

10

-11

_{up to 6 ps before the main pulse}

But, the overall reflectivity is only about 40%.

0 50 100 150 200 250 300 350 20 30 40 50 60 _(90,0.52) (290,0.59) (90,0.42)

Re

flectivi

ty (%)

Energy fluence

(

J/cm2

)

DPM system DPM only (290,0.48) (a) -500 -400 -300 -200 -100 0 100 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 -400 -200 0 200 400 0.0 0.2 0.4 0.6 0.8 1.0 In ten si ty ( ar b . u n its ) Time (fs) SPIDER SEQUOIA

In

te

nsity (ar

b.

uni

ts

.)

Time (ps)

without DPM with DPM (at 90 J/cm2) with DPM (at 290 J/cm2)

(b)

10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100

Int

e

ns

it

y

(

a

rb.u

nit

s

.)

_{without DPM} with DPM (at 90 J/cm2) with DPM (at 290 J/cm2)

(c)

-1 0 1 2 3 4 5 10-3 10-2 10-1 100 101 102

R

e

fle

c

tiv

ity

(%

)

with DPM (at 90 J/cm2) (d) 0 50 100 150 200 250 300 350 20 30 40 50 60 _(90,0.52) (290,0.59) (90,0.42)

Re

flectivi

ty (%)

Energy fluence

(

J/cm

2

)

DPM system DPM only (290,0.48)

(a)

-500 -400 -300 -200 -100 0 100 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 -400 -200 0 200 400 0.0 0.2 0.4 0.6 0.8 1.0 In ten si ty ( ar b . u n its ) Time (fs) SPIDER SEQUOIA

In

te

nsity (ar

b.

uni

ts

.)

Time (ps)

without DPM with DPM (at 90 J/cm2) with DPM (at 290 J/cm2)

(b)

-20-18-16-14-12-10 -8 -6 -4 -2 0 2 4 6 8 10 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100

Int

e

ns

it

y

(

a

rb.u

nit

s

.)

Time (ps)

without DPM with DPM (at 90 J/cm2) with DPM (at 290 J/cm2)

(c)

-1 0 1 2 3 4 5 10-3 10-2 10-1 100 101 102

Time (ps)

R

e

fle

c

tiv

ity

(%

)

with DPM (at 90 J/cm2)

(d)

100 TW DPM

PW DPM

14 14 Vacuum pulse compressor Plasma mirror system SPIDER and third-order cross-correlator Beam switching chamber Beam switching chamber Electron target chamber Proton and ion

target chamber X-ray target chamber Beam switching chamber Reflection mirror mounted on kinematic base Bottom plate Top plate

100 TW Laser Beam Delivery and Target Chamber System

Beam alignment monitor I. W. Choi et al., J. Korean Phys. Soc. 55, 517 (2009).

X-ray generation target chamber

Electron generation target chamber Proton / ion generation

target chamber

Beam delivery vacuum tube

Deformable mirror chamber

16 16 PW laser-plasma laboratory

PW target chamber

for solid target interaction

- Inner diameter : 2.2 m

- Depth : 1.07 m from bread board - Volume : ~4 m3

- Material : Stainless steel + Aluminum - Height of laser beam : 1.4 m

- PW laser beam size : ~20 cm

Two PW Target Chambers and Beam Delivery System

기존 튜 브 사 용 PW target chamber I PW target chamber II Beam switching chamber Beam switching chamber Beam switching chamber Plasma mirror system PW pulse compressor I PW pulse compressor II PW Amp. I PW Amp. II

Two Interaction Target Chambers Operated for PW Laser Application

Compressor I

Compressor II

Plasma mirror

PW Chamber II

PW Chamber I

Two interaction chambers

(Cylindrical and Rectangular)

18 18

Alignment of Off-Axis Parabolic (OAP) Mirror and Target

I. W. Choi et al., J. Korean Phys. Soc. 55, 517 (2009). 5-hole aperture OAP mirror Laser beam Laser focus Apochromatic lens Image relay system Beam splitter Beam splitter Mirror CCD camera CMOS camera Target position monitor Focal spot analyzer z x y Wavefront sensor Image of 5-hole aperture Install led in target chamber

Laser energy and pulse width on target : 8.5 J, 30 fs

Focal spot size obtained with f/3 OAP : 4

m

m

Energy concentration in FWHM area : > 25%

→

7

×

10

20

_W/cm

2

_{for PW laser + DPM}

Focal Spot Characterization and Focusing Intensity

0 10 20 30 40 50 0.0 0.2 0.4 0.6 0.8 1.0 Ene rgy c onc entrati on Radius (mm) > 25% in FWHM area -30 -20 -10 0 10 20 30 -30 -20 -10 0 10 20 30

V

ertical posi

tion

(

m

m)

Horizontal position (

m

m)

Focal spot size : 4.3 mm (FWHM) 0.0 0.2 0.4 0.6 0.8 1.0 -30 -20 -10 0 10 20 30 -30 -20 -10 0 10 20 30

V

ertical posi

tion

(

m

m)

Horizontal position (

m

m)

Focal spot size :

20 20

x

= +10

m

m

x

= +20

m

m

x

= +30

m

m

x

= +40

m

m

x

= +50

m

m

x

= +60

_x

_{= 0}

m

m

_m

m

Much better accuracy than Rayleigh range ~50 mm

-100 0 100

-100

0

100

-100 0 100

Before damage After damage

Damage Position (mm) Po sitio n ( m m) x y OAP mirror Target and its movement Laser beam Focal spot analyzer Target position monitor Lens _Beam splitter CCD CMOS

Accurate Target Alignment

Near-normal incidence

1. Commonly used targets : Al, Mylar, Si

₃

N

₄

, Diamond-like carbon, etc.

2. Alternative ultrathin target proposed

- Conjugate polymer material : F8BT, poly(9,90-dioctylfluorene-co-benzothiadiazole) - Polyfluorene derivative used for in polymer LED, organic solar cell and transistor

- Manufacture method : spin coating → floating on water → transferring to a target frame - Available thickness : 5-500 nm

- Chemical formula : (C₃₅H₄₂N₂S)_n

3. Advantages of the polymer target

- Easy manufacture, low material and production cost

- Low electron density of ~200 n_c for 800-nm wavelength laser

→ Realization of ultraintense laser-ultrathin target interaction using relatively low laser intensity, such as relativistic transparency, RPA, etc.

22 22

Ultrathin Free-standing Polymer Target

50 mm

20 nm-thick polymer

200-300 laser

shots

possible

with one loading

in target chamber

1.2-mm thick Al : r.m.s roughness ~1 mm 70 nm polymer 500 m m Roughness of 100-nm thick polymer Flatness of 100-nm thick polymer x (mm) y (mm) z ( m m) x (mm) y (mm) z (m m ) Free-standing polymer attached on target frame

Characterization of Nanometer-Class Polymer Target

0.0 0.1 0.2 0.3 0.4 -30 -20 -10 0 10 20 Heig ht ( nm) Position (mm) 16 nm

Alpha-step surface profiler - Thickness measurement range : > ~20 nm 101 102 103 -20 -10 0 10 20 Den t di ffer en ce ( m m) Film thickness (nm) Target frame Target 101 102 103 0 5 10 15 20 RMS r ou gh ne ss ( nm) Film thickness (nm) r.m.s roughness : < 10 nm Raleigh range >> dent distance → Frame surface alignment enough

24 24

X-ray reflectivity measurement

- Used for estimation of density, thickness, roughness - Critical angle for total external reflection :

X-ray Reflectivity Measurement for Thickness and Density

0.0 0.5 1.0 1.5 2.0 2.5 3.0 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 X -r a y r e fle cti vit y

Grazing incidence angle (Degree)

Spacing → Thickness Slope → Roughness 0.0 0.1 0.2 0.3 0.4 0.5 0.0 0.2 0.4 0.6 0.8 1.0 X -r a y r e fle cti vit y

Grazing incidence angle (Degree)

Critical angle q_c → Density 2 2 0 c o s 1 / c p q     0 / / c p n e n c q     Substrate Film q X-ray beam

0 20 40 60 80 100 0 5 10 15 20 25  = 0.77 g/cm3_, d = 26.8 nm  = 1.46 g/cm3, d = 40.0 nm  = 0.82 g/cm3, d = 53.1 nm  = 1.018 g/cm3_, d = 66.3 nm si n q m (  10 -5 ) m2  = 1.073 g/cm3_, d = 92.1 nm 0 100 200 300 400 500 600 0 2 4 6 8 10 12 14 16 18 20  = 1.18 g/cm3, d = 22.2 nm  = 1.20 g/cm3_, d = 28.3 nm  = 1.08 g/cm 3 , d = 55.8 nm  = 1.20 g/cm3, d = 75.8 nm si n 2 q m (  10 -4 ) 2  = 1.15 g/cm3_, d = 115.7 nm 2 s i n q Conjugated polymer, F8BT - Material density : 1.1-1.2 g/cm2

- Electron density : 3.5-3.8×1023_/cm3 _{for C}6+_{, H}+_{, N}7+_{, S}10+

→ 200-220 n_c for 800-nm laser wavelength

X-ray reflectivity measurement

- Intensity maxima

- Intercept with m2 _{= 0 → critical angle} q c

- Slope of the linear dependence → thickness d

- Thickness measurement range : > ~1 nm

2 2 2 s i n s i n m c d q  q  m  2 2 2 2 s i n s i n 2 m c m d  q  q _{ } _  

Thickness and Density of Nanometer-Class Polymer Target

0.0 0.1 0.2 0.3 0.4 0.5 0.0 0.2 0.4 0.6 0.8 1.0 Measurement Simulation

Incidence angle (degree)

Refl ec tiv ity (a. u.) Polymer q_c= 0.16o  = 1.15 g/cm3 Silicon q_c= 0.22o  = 2.307 g/cm3

26 26 0 1 2 3 4 5 100 102 104 106 108

Incidence angle (degree)

R eflec tiv ity (a . u.) Spin coating on Si Thickness d = 7.3 nm Measurement 0 1 2 3 4 5 100 102 104 106

108 _{Spin coating on quartz} + Transferring to Si Thickness d = 9.2 nm

Measurement Simulation

Incidence angle (degree)

R eflec tiv ity (a . u.) 0 1 2 3 4 5 10-1 101 103 105 107 _Measurement 4 nm, simulation 22 nm, simulation R eflec tiv ity (a . u.)

Incidence angle (degree)

Thickness Possible Down to ~4 nm

- Available thickness : < 5 nm

- Thickness reproducibility : ~90%

Thomson Parabola Spectrometer (TPS)

2 2 2 , 2 2 2 1 , ( 2 ) i i i i f f i i f q B L L q E L L x L y L m v m v m E E y x y x q B L L L B v      _  _  _  _        0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 E lec tr ic de flec tion po s it ion , y ( mm )

Magnetic deflection position, x (mm)

C+ _C2+ _C3+ _C4+ _C5+ _C6+ _H+

Constant momentum-to-charge line

Constant energy-to-charge line

Constant velocity line

0.5 MeV 1 MeV C1+ _C2+ C3+ C4+ C5+ C6+ H+ Constant energy- per-charge line 0 10 20 30 40 50 0 10 20 30 El ect ric de fle ct io n (mm) Magnetic deflection (mm)

Thomson parabola spectrometer

Beam collimator Ion detector (CR-39, MCP, plastic scintillator, imaging plate) Ions _E B Magnets B field E field Electrodes x y CCD or ICCD Lens and filters Mirror

28 28

Selection of scintillator thickness

Time-Of-Flight (TOF) Spectrometer

High energy ion Low energy ion Ion detector : Scintillator etc. Ion source Target Laser beam L   2 2 2 2 2 2 2 1 1 , 1 1 2 i i i i E m c L t E m c c _L E E c t m c m c                _  _                     Plastic scintillator (BC-408) Reflection mirror Photomultiplier tube a b b' a' Ion beam Lens Filters ( = 425 nm) Aperture 10-1 100 101 102 100 101 102 103 104 105 Plastic Scintillator (C₁₀H_) Density = 1.032 g/cm2 Project ed ra nge ( m m)

Ion beam High voltage power supply Oscilloscope Sweeping magnets Diode laser High voltage power supply Time-of-flight spectrometer Thomson parabola spectrometer Target Laser beam Screen -50 0 50 100 150 200 250 300 350 400 -500 -400 -300 -200 -100 0 t = 92.00 ns T = 1.683 MeV t = 11.80 ns P ho tomul ti pl ier tub e vol tag e ( V ) Flight time (ns) t = 5.50 ns 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 108 109 1010 1011 1012 P roton nu m be r (pa rt icl es/M eV /sr /l ase r sho t)

Proton energy (MeV)

Time-of-flight spectrometer Thomson parabola spectrometer

Noise level 0 5 10 15 20 25 30 35 40 45 50 55 0 5 10 15 20 E lectr ic de fl ecti on ( m m ) Magnetic deflection (mm) Zero-deflection point H+ 0.3 MeV 0.5 MeV 1.0 MeV 1.7 MeV E(up) E(down) E = 0

+

Ion Spectrometer Composed of TOF and TP Spectrometers

I. W. Choi et al., Rev. Sci. Instrum. 80, 053302 (2009).

0 5 10 15 20 25 30 35 40 0 2 4 6 E-de fl e ct io n (mm) B-deflection (mm) T/q = 1 MeV T/q = 2 MeV T/q = 3 MeV

Highest constant velocity line for carbon ions C+ _C2+ _C3+ _C4+ _C5+ _C6+ H+ TP spectrometer 1 10 0 50 100 150 c/ v Energy (MeV) TOF spectrometer Proton Carbon ion

30 30 B. Hidding et al., Rev. Sci. Instrum. 78, 083301 (2007)

Imaging plate

Ion Detectors : MCP, Imaging Pate (Limited Thickness)

Microchannel plate (MCP)

R. Prasad et al., Nucl. Instrum. Methods Phys. Res. Sect. A. 623, 712 (2010).

25

1.0

A. Mančić et al., Rev. Sci. Instrum. 79,073301 (2008)

Stopped energies in 1-mm glass : 13 MeV (Proton), 275 MeV (Carbon)

Response dependent on

- Ion energy and species

- Penetration depth of ions into the channel - Channel bias angle

- Open area ratio

http://www.detectors.saint-gobain.com E_p = 32.8 MeV for 10-mm plastic scintillator

Plastic scintillator

2 1 d E S d L d x d x _{d E d E} k B C d x d x             _{ }  _{ }     Quenching effect dL/dx = Flourescence light dE/dx = Energy loss S = Scintillation efficiency

Ion Detectors : Plastic Scintillator

32 32 0 5 10 15 20 0 5 10 15 20 Longitudinal di rection (mm) Latera_{l dire} ction (mm) Al + CR-39 stacks E_p = 40 MeV Longitudinal range = 13.1 mm Longitudinal straggle = 230 mm

Energy and Beam Profile Measurement Using Stacked Detectors

100 101 102 10-2 10-1 100 101 102 Pro je cte d ra ng e (m m )

Proton energy (MeV)

CR-39 Range 0 5 10 15 20 25 0 10 20 30 40 50 60 Pro to n e ne rgy (m m ) Detector depth (mm) 0 5 10 15 20 En ergy lo ss (M eV/m m ) Al + CR-39 stacks 50 MeV 40 MeV 30 MeV 20 MeV 10 MeV

F. Nürnberg, Rev. Sci. Instrum. 80, 033301 (2009)

Proton Acceleration Using PW Laser Pulses

Mirror

Mirror Mirror

OAP

f = 80cm Target surface _monitor

Target Focal spot monitor CR39 Proton beam To Thomson Parabola Target : polymer Thickness : from 10 nm to 100 nm Intensity range w/ PM : 0.5×1020 _W/cm2 _{– 3.3×10}20 _W/cm2

Linear pol. : s-pol on the target

34 34 6th CR39 7th CR39 8th CR39 9th CR39 10th CR39 1.2cm 1.2cm 1st CR39 2nd CR39 3rd CR39 4th CR39 5th CR39

8.96<E<9.21 MeV 13.14<E<13.34 MeV 16.42<E<16.962MeV 19.22<E<19.48 MeV

1.14<E<1.72 MeV

21.78<E<21.99 MeV 24.04<E<24.31 MeV 26.15<E<26.54 MeV 28.18<E<28.46 MeV 30.08<E<30.36 MeV

Zero order

20 MeV (H+₎ 10 MeV (H+₎ 75 MeV (C6+₎ 60 MeV (C6+₎ 30 MeV (C6+₎

H

+

C

6+ 6th CR39 7th CR39 8th CR39 9th CR39 10th CR39 1.2 cm 1.2 cm 1st CR39 3rd CR39 4th CR39 5th CR39

8.96<E<9.21 MeV 13.14<E<13.34 MeV 16.42<E<16.962MeV 19.22<E<19.48 MeV

21.78<E<21.99 MeV 24.04<E<24.31 MeV 26.15<E<26.54 MeV 28.18<E<28.46 MeV 30.08<E<30.36 MeV

(27.8deg.= 485 mrad) (0.3deg.= 5.2 mrad) 1.14<E<1.72 MeV 2nd CR39 30 MeV (H+₎ 20 MeV (H+₎ 10 MeV (H+₎ 90 MeV (C6+₎ 60 MeV (C6+₎ 30 MeV (C6+₎

Zero order

H

+

C

6+

- Target thickness :

30 nm

- Laser intensity :

3.3

×

10

20

_W/cm

2

Good Agreement between TPS and CR-39 Measurement

0 10 20 30 40 50 0 5 10 15 20 Lon gitudinal rang e (mm)

Proton energy (MeV)

5 10 15 20 25 30 35 108 109 1010 d N / d E ( a. u .)

Proton energy (MeV)

- Target thickness :

70 nm

- Laser intensity :

3.3

×

10

20

_W/cm

2

Good Agreement between TPS and CR-39 Measurement

4 6 8 10 12 14 16 18 20 22 108 109 1010 d N / d E ( a . u .)

Proton energy (MeV)

36 36

45 MeV Proton Energy Achieved with 10-nm Thick Polymer



Thomson parabola and ion energy spectra obtained with a

3.3

×

10

20

_W/cm

2

_{laser intensity and}

10-nm thick polymer

target



Continuous energy increase until 10-nm target implies the high performance of double

plasma mirror system,

very high contrast up to several ps

before main pulse arrival.

Conclusions

Laser beam

 Well-controlled temporal and spatial properties

 Low- or high- contrast, depending on target type

 Rough alignment for each shot and robust shooting - Reproduced focusing quality

- Precise target positioning onto laser focus

Target

 Production of ultrathin targets with large area

 Cost effective, stable, and reproducible way

 New and exotic targets : foam, nano-structure

Diagnostics system

 Real-time and fast characterization

 Extending detection range to ~100 MeV and higher

Several issues solved already or to be solved for real applications

Thank you for your attention

38 38

Electron

Spectrometer and Detection

Magnets Beam

collimator

Electron detector for high energy B field

Electrons

ICCD Electron detector

for low energy

10 50 0.91 T 1.4 T 30 Lens and filters Mirror C. M. S. Sears et al., RSI 81, 073304 (2010).

Optional depending on detector

0 10 20 30 40 50 0 5 10 15 20 Z Deflection mm Y De fl ec ti o n mm B = 0.52 T E_e = 1.2 – 10.8 MeV Electron detector 2 e = f o r e m c E E m c e B e c B    

40 40

Electron Detectors : Imaging Pate, Lanex

Structure of BAS-SR imaging plate

Protective layer 6 µm PEF Photostimulable phosphor layer thickness : 120 µm Phosphor : BaFBrI:Eu2+ Support layer : 190 µm PET 160 µm ferrite layer photo-stimulated luminescence (PSL)

Response of BAS-SR to electrons K. A. Tanaka, RSI 76, 013507 (2005). Y. Glinec, RSI 77, 103301 (2006).

Emission spectra of Lanex screen

Composition of the Lanex screen.

Composition of Kodak Lanex Fine screen

Energy deposited in the scintillator layer of Lanex Fine screen

Lanex screen : Kodak

Imaging plate : Fuji film

B = 0.45 T, s = 0.1 m, q = 30 mrad B = 0.45 T, h = 6 mm (s = 20 m, q = 0.3 mrad) B = 0.45 T, s = -0.1 m, q = 30 mrad 5 10 15 19 MeV 5 10 15 MeV 2 2 2 2 2 x x x q     q         _{ }  _{ }     _{ }

Enhancement in Energy Resolution Adapting Focusing Geometry

    2 2 3 2 2 3 2 x x x d f d a d f d d d f d f q  q  q   q              _{ }         _  _{  }            _{   }  _{  }    _  _{  }   _{ }  _{ }            

for non-focusing geometry

42 42 ESM at q = -56.25o TOF at q = 22.5o ESM at q = -11.25o ESM at q = 11.25o ESM at q = 33.75o CIS at q = 0o CIS at q = -22.5o Target ESM at q = -33.75o Scattering screen Visible spectrometer Laser beam (p-pol., 22.5o₎

CIS : Composite ion spectrometer ESM : Electron spectrometer

TOF : Ion time-of-flight spectrometer

1 2 3 4 5 6 7 8 9 106 107 108 109 1010 1011 1012 _{Al 1.2 mm} Polymer 70 nm Pro to n n um be r (1 /M eV/s r)

Proton energy (MeV)

0-degree (Target normal) 22.5-degree 1 2 3 4 102 103 q = -56.25o q = -33.75o Ele ctro ns / M eV (a . u .)

Electron energy (MeV)

q = -11.25o q = 11.25o q = 33.75o T_e = 0.65 MeV T_e = 1.2 MeV 0.01 0.1 1 10 0 2 4 6 8 M ax im um p rot on e ne rgy (M eV) Target thickness (mm) 0-degree (Target normal) 22.5-degree

Proton Energy and Electron Spectra Dependent on Observation Angle

0.5 1.0 2.0 3.0 E (MeV) 0.5 1.0 2.0 3.0 E (MeV) B = 0.17 T q = 33.75o B = 0.52 T q = 11.25o B = 0.52 T q = -11.25o B = 0.52 T q = -33.75o B = 0.17 T q = -56.25o 2 4 6 8 E (MeV) 10 35 fs(FWHM) , 22.5o _{incidence angle} I = 4×1019 _W/cm2_{, a} 0 = 4.33,

Polymer 70 nm Polymer 20 nm 0 5 10 15 20 25 30 35 40 45 50 55 0 5 10 15 Elec tric def lec tion (m m ) Magnetic deflection (mm) 0.5 MeV 1 MeV C+ _C2+ _C3+ _C4+ _C5+ _C6+ Proton 20090831-1_4

Maximum proton energy obtained : 8 MeV

1 2 3 4 5 6 7 8 9 107 108 109 1010 1011 1012 Al 1.2 mm Polymer 70 nm Prot on num ber (1/ M eV/ s r)

Proton energy (MeV)

Laser Target Protons Carbon ions included Polymer Aluminum 0.01 0.1 1 10 1010 1011 0.0 0.5 1.0 4 6 8 d N to t / d  ( 1/ sr ) Target thickness (mm) T p ( M eV ) E m a x ( M eV )

44 44 1.2-mm thick aluminum 70-nm thick polymer 2 3 4 5 6 7 108 109 1010 1011 1012 100 101 102 103 104 Experiment P ro to n n u m b e r ( 1 /M e V /s r)

Proton energy (MeV)

T p = 1.1 MeV Simulation P ro to n n u m b e r ( A .U .) 2 3 4 5 6 7 107 108 109 1010 1011 1012 100 101 102 103 104 Experiment P ro to n n u m b e r ( 1 /M e V /s r)

Proton energy (MeV)

T_p = 1.18 MeV Simulation P ro to n n u m b e r ( A .U .)

- I

= 5

×

10

19

_W/cm

2

_,



_{= 5}

m

_{m (FWHM),}

t

_{= 34 fs,}

- Linearly polarized pulse, 22.5-degree incident angle

- Assuming initial plasma density :

n

= 250

n

_cr

(Simulation with ALPS-2D code)

Proton density map at 216 fs

Laser pulse

Optimal Target Thickness Well Agreed with PIC Simulation

Competition of two opposite tendencies :

- Large recirculation effect at thinner target : enhancing n_e

- Large laser absorption at thicker target : enhancing T_e

Accelerating sheath electric field

in TNSA

B e s h e a t h e B e D 4 k T E n k T e     1 2 3 4 5 6 7 8 100 101 102 103 104 10 nm 20 nm 30 nm 70 nm 150 nm 400 nm Proton num ber ( A.U.)

Proton energy (MeV) 10 100

3 4 5 6 7 8 9 Proton ene rgy (MeV ) Target thickness (nm)

46 46 2 0 r e l S k i n d e p t h : , w h e r e 1 s p e p e c c l   a       2 2 2 2 r e l D i s p e r s i o n r e l a t i o n : , p e c c c k n n       

Relativistic Transparency Effect at the Thinnest Target : RPA

10-nm target

20-nm target

r e l 0 4 . 4 4 , 1 9 n m f o r 4 . 3 3 c c s n  n l  a  -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0 10 20 30 345 350 17.5 fs 35.0 fs 52.5 fs 70.0 fs E le ctr o n d e n sit y ( n c ) Position (mm) -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0 50 100 150 200 600 650 17.5 fs 35.0 fs 52.5 fs 70.0 fs E le ctr o n d e n sit y ( n c ) Position (mm)

- The 2 spectra were not detected (or were nearly at the noise level) in the case of Al targets. - The 2 intensity shows similar dependence on the target position to proton energy.

Strong 2



(in Experiment) and HOH (in PIC Simulation) Observed

Incident laser beam profile on target

Reflected beam profile from target

Target Reflected bream Incident laser beam Visible spectrometer Screen

PIC simulation on the harmonic generation with PIC simulation code

Incident laser beam Transmitted beam Reflected beam 10 mm -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0 1 2 3 4 5 6 7 0 1 2 3 4 5 En ergy ra tio o f 2  to  (% ) Target position (mm) Pro to n e ne rgy (M eV) E_max E2 /E 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0 2 4 6 8 In te ns ity (a . u .) Wavelength (mm)  : saturated Second order of  2 0 2 4 6 8 10 12 14 16 18 20 10-4 10-3 10-2 10-1 100 Harm on ic in te ns ity (a . u .) Harmonic order Reflected HOH Transmitted HOH

48 48

PW (PUSER) and 100 TW (LiFSA)

Ti:Sapphire

Laser System

PULSER (1 PW : Petawatt Ultrashort Laser Source for Extreme science Research)

LiFSA (100 TW : Light source for Femto Science and Applications)

(First Power Amp.) (Second Power Amp.)

(Booster Amp.) (Booster Amp.)



Flat-field soft x-ray spectrometer with varied line-spacing concave grating

- Components : Varied line-spacing concave grating (1200 or 2400 grooves/mm),

Entrance slit, Toroidal mirror, Soft X-ray detector(e.g. CCD), Vacuum housing



Space-resolving capability using pre-focusing optics

- Increasing light collection efficiency - Source characterization vs position

S a g i t t a l D i r e c t i o n : F o r m a t i o n o f S p e c t r a l I m a g e S p e c t r a l L i n e W a v e l e n g t h M e r i d i o n a l D i r e c t i o n : F o r m a t i o n o f S p e c t r a l L i n e

Space-Resolving Flat-Field Soft X-ray Spectrometer

1 1 1 1 1 1 1 1 2 T a n g e n t i a l F o c u s i n g c o s 1 1 2 c o s S a g i t t a l F o c u s i n g m s r r R r r a a          G r a t i n g T o r o i d a l m i r r o r S p e c t r a l p l a n e ( s o f t x - r a y d e t e c t o r ) S l i t L r  1 a1 1 z 1  ' r m1' r m2  ' a 2 2  ' '  ' '  2 z 2 M e r i d i o n a l P l a n e r s2 r A p e r t u r e s t o p 0 rs1'  0' ' 0' M e r i d i o n a l p l a n e S a g i t t a l P l a n e

50 50 10 100 10-3 10-2 10-1 Diffraction order m = -1 m = -2 m = -3 m = -4 m = -5

D

iff

racti

on

E

ff

ici

en

cy

Wavelength (A)

0 10 20 30 40 50 60 70 80 90 100

10

-3

10

-2

10

-1 Diffraction order m = 1 m = 2

D

iff

racti

on

E

ff

ici

en

cy

Wavelength (A)

Blaze wavelengths

- m



_b0

= 100.5 Å for 1200 grooves/mm grating

- m



_b0

= 15.7 Å for 2400 grooves/mm grating

1200 grooves/mm

grating

2400 grooves/mm

grating

D. G. Lee et al., Appl. Phys. Lett. 81, 3726 (2002).

Spectrally resolved divergence measurement of high-order harmonics

H. T. Kim et al., Phys. Rev. A 67, 051801(R) (2003).

Continuously wavelength-tuned high-order harmonics from He atoms

High Order Harmonics from Gas (He, Ar) Target

Sagittal focusing (Toroidal mirror) → Enhancing light collection Sagittal diverging (Cylindrical mirror) → beam profile measurement

52 52

RHHG with High and Low Contrast Laser Pulses

I J. Kim, K.H. Pae, C.M. Kim, H.T. Kim, H. Yun, S.J. Yun, J.H. Sung, S.K. Lee, J.W. Yoon, T.J. Yu, T.M. Jeong, C.H. Nam, and J. Lee, “Relativistic frequency upshift to the XUV regime using self-induced oscillatory flying mirrors,” Nat. Commun. (accepted).

Highest Relativistic Harmonics with < 100 fs Laser Pulses

I = 9×1019 _W/cm2 (a₀=6.5) 1000 800 600 400 200 Maximum order : 43th n-8/3 I = 4.5×1019 _W/cm2 _(a 0=4.6) Harmonic order

54 54 Pinhole and x-ray filter CCD camera a b M = b / a = ~10, Resolution = d(1+1/M)

Hard X-Ray Image Acquisition with X-Ray Pinhole Camera

Gate valve X-ray filter Pinhole Hard X-ray CCD 0 5 10 15 20 25 0.1 1 Al 1 mm Al 3 mm Be 10 mm Be 25 mm Tra ns m is sio n

Photon energy (keV)

X-ray filter selection for E > 1 keV

K edge : 1.5596 keV

70 mm (Full Width) 30 mm (FWHM)

(c) -0.1 0.0 0.1 0.2 20 40 60 80 100 F W H M o f x-ray ima g e ( m m) Target position (mm) (d) -0.1 0.0 0.1 0.2 0.5 1.0 1.5 2.0 2.5 0.5 1.0 1.5 Ma xi mu m p ro to n e n e rg y (Me V) Target position (mm) Pea k in te n si ty (1 0 18 W /cm 2 ) x = 0.2 mm x = 0.1 mm x = 0 x = -0.1 mm x = -0.3 mm (b) x = 0.2 mm x = 0.1 mm x = 0 x = -0.1 mm x = -0.3 mm (a) x > 0 x < 0 Laser Target

Correlation between Laser Focus Image, X-ray Image and Proton Energy

      2 2 m a x h o t p p p p i a c c 2 2 1 8 h o t p e 2 s h e a t h 0 0 l a s e r p s h e a t h 2 l n 1 , / 2 1 / 1 . 3 7 1 0 1 t a n , / e E T t t t t e T U m c I S r d n f E c t U S m    q                      

Self-similar, isothermal, fluid model

- P. Mora, PRL 90, 185002 (2003).

- J. Fuchs, NP 2, 48 (2006).

56 56

Contrast Ratio Enhancement Using Double Plasma Mirror System

0 50 100 150 200 250 300 350 20 30 40 50 60 _(90,0.52) (290,0.59) (90,0.42) Re flectivi ty (%) Energy fluence (J/cm2) DPM system DPM only (290,0.48) (a) -500 -400 -300 -200 -100 0 100 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 -400 -200 0 200 400 0.0 0.2 0.4 0.6 0.8 1.0 In ten si ty ( ar b . u n its ) Time (fs) SPIDER SEQUOIA In te nsity (ar b. uni ts .) Time (ps) without DPM with DPM (at 90 J/cm2) with DPM (at 290 J/cm2) (b) -20-18-16-14-12-10 -8 -6 -4 -2 0 2 4 6 8 10 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 Int e ns it y ( a rb.u nit s .) Time (ps) without DPM with DPM (at 90 J/cm2) with DPM (at 290 J/cm2) (c) -1 0 1 2 3 4 5 10-3 10-2 10-1 100 101 102 Time (ps) R e fle c tiv ity (% ) with DPM (at 90 J/cm2) (d) ~4.2 ps >1011

(a) Reflectivity as a function of the energy fluence incident on the first PM. (b) Temporal profiles of the laser beam between -500 ps and +150 ps, (c) between -20 ps and +10 ps and (d) Time-resolved reflectivity for the energy fluence of 90 J/cm2 _{on DPM. The}

inset in Fig. (b) shows the temporal profiles of laser pulse measured with SPIDER and SEQUOIA respectively.

Shock

wave speed : ~10 mm/ns

~10 nm/ps Reflectivity of plasma mirror system : > 40% for

laser energy fluences