recent progress in laser wakefield acceleration experiments...

Recent Progress in Laser Wakefield

Acceleration Experiments at APRI

Nasr. A. M. Hafz

Advanced Photonics Research Institute (APRI)

Gwangju Institute of Science and Technology (GIST), Korea

• Introduction

• Recent Results in the Field by other groups

• Recent Results at APRI

• Summary

Outlines

Laser interaction with an electron in vacuum

electron

ponderomotive force

C. A. Brau “Classical Electrodynamics”

218 /10 cmW& above

BVeEeF

218 /10 cmWI Plane wave

electron

electron

EeF

Longitudinal

Motion

Quiver Energy

]/[][106.8 210

0 cmWIma

00/)()( acmeAu

2/)1(]/)([)( 0

2

000 cmeAuz

2/)1(]/)([1)( 0

2

00 cmeA

Transverse

Motion

E

B

e

n

Electron motion

plasmaIntense

laser ion

electrons

Es

Charge separation

Plasma wave

Es

Wave breaking &

Electron acceleration

Excitation of Plasma Wakefield by Lasers

T. Tajima and J. Dawson-PRL 1979

1100 pL fs

Ions are immobile, plasma in stable

2

2

0

2

8Ef

p

p

Ponderomotive force

Electron acceleration in the Wakefield Bubble

Hafz et al., Nature Photonics, 2, 571, (2008).

p ~ 20 m

Plasma

Laser pulse

Femtosecond Electron bunches Wakefield Bubble

8.7 m

4.2

m Ma

ste

rO

scilla

tor

Stretcher

Regen. Amp.

Pre-Amp.

1st Main Amp. 2nd Main Amp.

Va

cuu

mC

om

pre

ssorPump Laser 2 Pump Laser 5

Pump Laser 4 Pump Laser 6

Pump Laser 3

Pu

mp

La

se

r 1

Pum

p L

aser 7

Pum

p L

aser 9

Pum

p L

aser 8

Pum

p L

aser 1

0

Pum

p L

aser 1

1P

um

p L

aser 1

2Pump Laser 13

Pump Laser 14

4. Pre-Amp.: 4 pass, 50 mJ, 130-mJ pump at 10 Hz

5. 1st Amp.: 4 pass, 1.8 J with 4.4-J pump at 10 Hz

(35 TW with direct pulse compression)

1. Master Oscillator: 20 fs, 6 nJ

2. Stretcher: 500 ps

3. Regen. Amp.: 1 mJ with 10-mJ pump at 1 kHz

(10 Hz after pulse picker)

6. 2nd Amp: 2 pass, 5.0 J with 12-J pump at 10 Hz

7. Compressor: 3.5 J, 32 fs, >100 TW at 10 Hz

Green pump lasers

Pump Laser 1: Nd:YLF (SHG), 527 nm,

10 mJ at 1 kHz (JADE series)

Pump Laser 2: Nd:YAG (SHG), 532 nm,

200 mJ at 10 Hz (COMP series)

Pump Laser 3-14: Nd:YAG (SHG), 532 nm,

1.2 J at 10 Hz (SAGA series)

100TW 30fs Ti:Sapphire Laser at UQBF, APRI, 2006

3.5 J, 32 fs, >100 TW at 10 Hz

http://apri.gist.ac.kr/

Pu

mp

po

we

r su

pp

lies

Pulse compressor

Target Chamber

Oscillator

Stretcher

Regenerative

Master Clock

Laser-Driven Electron Beams Before 2004 (Example: LOA Results)

(V. Malka, Science 2002)

Quasi-monoenergetic Electron Beams (2004-2007)

1 GeV in

Plasma

capillary

33 mm

Leemans et al., Nature Phys. 2, 696 (2006)

50 TW, 40 fs

30 TW, 30 fs

200 MeV in

Gas jets

Few mm

V. Malka

Our Recent Results

Self-modulated LWFA at KERI in 2003-2005

)( BVEeFLorenz

Laser: 2TW ~ 1ps

ND: Glass

Gas jet: 0.8 mm He and N

ICT: 1pC resolution

Magnet: up to 10 MeV

Al-foil: 16 um

Hafz, Hur, G. Kim, C. Kim, H. Suk, Phys. Rev. E, 73, 016405 (2006)

1.81.4 2.6 E (MeV)4 10

Laser beam

position

200

383

567

750

200pC

< 100 % dE/E (Energy Spread)

700 800 900 1000 1100

250

300

954 nm

0= 1054 nm

739.9 nm

858 nm

Inte

nsity

(a.

u)

Wavelength (nm)

1.6x1019

2.4x1019

3.2x1019

4.0x1019

4.8x1019

2.4

2.8

3.2

3.6

4.0

4.4

Plasma density(cm-3)

En

erg

y (

Me

V)

Energy

100

200

300

400

Charge

Ch

arg

e (p

C)

Forward Raman Scattering

Self-modulated LWFA at KERI in 2003-2005

Hafz, Hur, G. Kim, C. Kim, H. Suk, Phys. Rev. E, 73, 016405 (2006)

Energy Spectrum from Nitrogen Plasma

Helium Plasma

Hafz, G. Kim, C. Kim, H. Suk, Int. J. Mod. Phys. B. 2007

Laser Wakefield Acceleration at APRI in 2006

Experimental Parameters

Plasma (He) density = 11019 cm-3

Laser pulse duration = 30 fs

Plasma length = 4 mm

Laser power ~ 20 & 40 TW

Spot size: 10 , 25, 30 m

Spherical mirror

(f= 75 or 100 cm)

4 mm slit nozzle

ICCD

LanexDipole magnet

0.8 T

Laser pulse

10 mm hole

M

37 cm

N. Hafz et al., Appl. Phys. Lett. 90, 151501 (2007)

LWFA in the f/2.5 focusing geometry: 10 m spot size

Deflection of electron beam

4 mm

Laser

Laser break up and filamentation

The f/2.5 focusing is very tight and it results in deflection and break up of the laser and electron beams.

Electron Beam

Profile

Laser-produced

Plasma

N. Hafz et al., Appl. Phys. Lett. 90, 151501 (2007)

Soft focusing

I ~ 5.61018 W/cm2

ne ~ 1 10 19 cm-3

Rayleigh Length ~ 1.7 mm

Gas jet length ~ 4 mm

Well collimated beam

Divergence 8 mrad

Electron beam spatial profile

B = 0

LWFA in the f/10 focusing geometry: 25 m spot size

Energy (MeV)

130 40 24

0 1313 2625 3500

0.6

0.8

1.0

1.2

1.4

1.6

Inte

ns

ity

(a

.u.)

Energy (MeV)40 130 24

105

4 mm

Laser

500 m long channel

LWFA in the f/10 focusing geometry

The f/10 focusing is relatively stable and it results in quai-monoenergetic electron beam generation.

Energy Spectrum

Laser-produced

Plasma

Charge = 20 pC

N. Hafz et al., APL, 90, 151501 (2007)

5

6

7

8

40

30070

Inte

ns

ity

(a

rb

.u)

Energy (M eV)145

3

4

5

5030

1.99 mm shift

Inte

ns

ity

(a

rb.u

)

Energy (MeV)330

Small mono-peaks

1.5 mm long channel= dephasing length25 m diameter

LWFA in the f/14 focusing geometry: 30 m spot size

N. Hafz et al., APL, 90, 151501 (2007)

Plasma channel

Energy Spectrum Energy Spectrum

Effect of Laser Spot Size on LWFA

A. Thomas et al. Phys. Rev. Lett. 98, 095004 (2007)

Laser Pulse

Wakefield

2

00

wz

Ld > cm

(ne~ 1018cm-3 is enough )

50 TW

35 fs

f#/21.4

fsa laser30,10

Uniform cm channel

Plasma Bubble

p

Gas jet

Long Rayleigh Range, several mm’s.

High laser power that leads to relativistic self-focusing

Long Dephasing Length, 1 cm, so higher electron energy

2)/(17)( pc GWP

ppd aL )/(2 222

0

]/[][106.8 22/110

0 cmWIma

Experiments in the bubble regime 2007

Experimental Scheme for Generation of Stable Electron Beams

Lens

LensLanex

Al filter

Up to 50 TW, 35 fs Laser Pulses

Nozzle

Gasjet

8-bit

CCD

12-bit

CCD

ElectronBeam

Top View Monitor

Side View Monitor

Filter

Filter

Spherical

Mirror

f =1.5 m

ICT

S

N

20 cm

Lens

Mirror

Band-pass

filter

Gated

ICCD

Electron Beam Energy Monitoring

Mirror

with Hole

B = 0.94 T

10 mm

5 mm channel

42 cm

Wave-front corrected

225 MeV Electron Beam Generation: 4 mm nozzle, 27 TW laser

Hafz, et al., Nat. Photon. 2, 571 (2008)

Quasi-momoenergetic

ReproducingLOA 2004-Nature

Input Parameters

Laser: 27 TW, 35 fs, 24 m (FWHM)

Plasma: 4 mm gas jet, Density: 71018 cm-3

Dephasing length= 3.1 mm

Electron Beam

Energy: 225 MeV, Charge: 100 pC

Divergence: 5.8 mrad (FWHM)

Energy Spread: 7 %

170-200 MeV Beams by 27 TW Laser Pulses

225

# 189

# 190

E peak =174 MeV

E spread= 32 %

E peak=192 MeV

E spread= 41%

# 191

Epeak = 190 MeV

E spread= 49 %

# 188

E peak=178 MeV

E spread= 33 %

27 TW, 35 fs, 24 m spot size

4 mm nozzle, no~ 7 1018cm-3,

Ld ~ 3.16 mm

Charge: 100 pC

Average Channel length ~ 3.5 mm

Mean Laser (J) = 36.8 TW

SD/Mean E = 4.6 %Intensity (arb.u.)

Div

erg

en

ce

An

gle

(m

rad

)

Electron Beam Energy (MeV)

Intensity (arb.u.)

Reproducible Quasi-monoenergetic Beams: 4 mm Gas Jet

Mean Energy = 236.9 MeV

SD/Mean E = 5 %


Charge: 200 pC

Generation of 330±17MeV Electron Beams and 4 mm Gas Jet

Max


Laser: 50TW, 35 fs, 24 m (FWHM)

Plasma: 4 mm gas jet

Density: 6.61018 cm-3

Dephasing length= 3.3 mm

Electron

Beam: Peak at 330 MeV, Max. at sub GeV,

Charge: ~500 pC

Divergence: few mrad (FWHM)

Energy Spread: ~ 30 %

Beam Energy Doubling

by doubling the

Laser power

Peak = 300±30 MeV

E spread = 50 %

# 582

Peak=320±25MeV

E spread = 31 %

# 583

Peak = 303±9 MeV

E spread= 30 %

# 584 # 586

Peak = 285±12 MeV

E spread= 42 %

50 TW, 35 fs, 24 m spot size, 4 mm nozzle, no~

6.5-6.8 1018cm-3,

Ld ~ 3.16 mm

320±25 MeV Beams by 50 TW Laser Pulses and 4 mm Gas Jet

Four successive shots with small change in density

1 Centimeter Gas Jet Results

Quasi-momoenergetic Electron Beams


Laser: 50TW, 35 fs, 24 m (FWHM)

Plasma: 1 cm gas jet

Density: 3.41018 cm-3

Dephasing length 1 cm

Epeak1= 540 MeV, Emax1> 1 GeV,

Epeak2= 320 MeV,

E 2spread= 11%, E1spread= 30%,

Qpeak1=200 pC & Q peak2 = 20pC

5 mm Channel

Epeak= 480±60MeV

Espread= 23 %

# 328

Epeak= 480±15 MeV

Epeak= 320±10 MeV

# 330

Epeak= 500±20 MeV

Epeak= 330 MeV

# 333

Div

erg

ence

(mra

d)

Energy (MeV)

Epeak= 500±20 MeV

½ GeV Electron Beam Generation

50 TW, 35 fs, 24 m spot size, 10 mm nozzle,

no~ 3.4 1018cm-3,

Ld ~ 10 mm

# 327

5 mm Channel

R. Bingham et al., Plasma Phys. Cont. Fus_34, 557(1992)

Asymmetric laser pulse

with fast rising time

generates larger

wakefield intensity

Case 1: Low density 21018 cm -3

Case 2: High density 31019 cm -3

G X

e

i78.5 cm

40 cm

BP

L

M

Pb

d

l

2009 Experiment at APRI

Initial Laser-Plasma Parameters Experimental Scheme Laser pulse energy 0.8 0.9 J (= 800 nm, 50 nm FWHM)

Laser Spot size (FWHM) 25 µm.

Pulse duration 37 fs (symmetric pulses)…

(Intensity 1.46 ×1018 W/cm2, a0 = 0.83).

Pulse duration 74 fs (asymmetric at the grating detuning of -200 µm)

(Intensity 7.5 ×1017 W/cm2 (Nonrelativistic ) a0 = 0.59).

Target: Gas Jet of Helium: 4 mm long

Density (very low): 10171018 cm-3.

Interaction length 3 ~ 4 mm.

a0 1, c ≤ w0 p

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.30

100

200

0.0

0.2

0.4

0.6

0.8

1.0 FWHM

FW

HM

(fs

)

Detuning (mm)

No

rma

lize

d P

ea

k In

ten

sity

Peak Intensity

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-250um

200um

-150um

-100um

-50um

0um

150um

100um

50um

200um

200um

Laser Pulse Compressor Detuning

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-150 -100 -50 0 50 100 150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Inte

nsi

ty (

x10

16W

/cm

2)

Time (fs)

-250 m

- 200 m

0 m

Asymmetric Laser Pulses

50 fs FWHM

75 fs FWHM

37 fs FWHM

-0.5 -0.4 -0.3 -0.2 -0.1 0.0

0

20

40

60

80

100

Unstable

Weak

Less Stable

Weak

Grating detuning (mm)

Po

intin

g a

ng

le (

mra

d)

Laser Height = 3.25

Horizontal

Vertical

Stable

Bright

Pointing Angle Optimization

Hafz et al., Applied Physics Express 3(2010) 076401

Density: 10171018 cm-3

-500 -400 -300 -200 -1002

4

6

8

10

12

14

D

ive

rge

nce

(m

rad

)

Grating Detuning (m)

Horizontal

Vertical

Electron Beam Divergence

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700

Horizontal Axis (pixels)

Ve

rtic

al A

xis

(p

ixe

ls)

0

2000

4000

6000

8000

10000

1.200E4

1.400E4

1.600E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

6250

1.250E4

1.875E4

2.500E4

3.125E4

3.750E4

4.375E4

5.000E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

3250

6500

9750

1.300E4

1.625E4

1.950E4

2.275E4

2.600E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

2250

4500

6750

9000

1.125E4

1.350E4

1.575E4

1.800E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

3500

7000

1.050E4

1.400E4

1.750E4

2.100E4

2.450E4

2.800E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

3250

6500

9750

1.300E4

1.625E4

1.950E4

2.275E4

2.600E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

3250

6500

9750

1.300E4

1.625E4

1.950E4

2.275E4

2.600E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

7000

10000

2.000E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

7000

10000

2.000E4

3.000E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

5625

1.125E4

1.688E4

2.250E4

2.813E4

3.375E4

3.938E4

4.500E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

1750

3500

5250

7000

8750

1.050E4

1.225E4

1.400E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

4375

8750

1.313E4

1.750E4

2.188E4

2.625E4

3.063E4

3.500E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

4375

8750

1.313E4

1.750E4

2.188E4

2.625E4

3.063E4

3.500E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

7000

1000

2000

3000

4000

5000

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

6250

1.250E4

1.875E4

2.500E4

3.125E4

3.750E4

4.375E4

5.000E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

2250

4500

6750

9000

1.125E4

1.350E4

1.575E4

1.800E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700

1.96 mm 5 mrad

0

2000

4000

6000

8000

10000

1.200E4

1.400E4

1.600E4

10 mm= 25.4 mrad

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

5625

1.125E4

1.688E4

2.250E4

2.813E4

3.375E4

3.938E4

4.500E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

5000

10000

1.500E4

2.000E4

2.500E4

3.000E4

3.500E4

4.000E4

500 525 550 575 600 625 650 675

500

525

550

575

600

625

650

675

700 0

5000

10000

1.500E4

2.000E4

2.500E4

3.000E4

3.500E4

4.000E4

Electron Beam from 20 Successive Shots

Hafz et al., Applied Physics Express

3(2010) 076401

500 520 540 560 580 600 620 640

500

520

540

560

580

600

620

640

4 mrad

Ve

rtic

al (

pix

els

)

Horizontal (pixels)

Vertical

4 mrad

G X

e

i78.5 cm

40 cm

BP

L

M

Pb

d

l

Unambiguous Electron Beam Energy Measurement

Laser pulse length 74 fs (asymmetric)

(Intensity 7.5 ×1017 W/cm2

(Non-relativistic ) a0 = 0.59).




Electron Beam Energy at Optimum Detuning & Height

150 310 MeV

#1766

150 240 MeV

#1747

-500 -400 -300 -200 -100 0 100100

150

200

250

300

350

Original position

for shooting > 100 fs

75 fs

Range

37-40 fs Range

Grating Detuning (m)

Ele

ctro

n E

ne

rgy

(Me

V)

Electron Energy

Hafz et al., in preparation

Electron Beam Energy at Optimum Detuning & Height

0

2000

4000

6000

8000

10000

Electron Energy (MeV)

Sig

na

l Inte

nsi

ty (

arb

. un

its)

1754

380 2401801501200

4000

8000

12000

16000

1767

380 240180150120

Sig

na

l In

ten

sity

(a

rb. u

nits

)


500

1000

1500

2000

2500

3000

3500

4000

1748

380 240180150120


Sig

na

l Inte

nsi

ty (

arb

. un

its)

0

2000

4000

6000

8000

10000

12000

1765

380 240180150120

Sig

na

l Inte

nsi

ty (

arb

. un

its)


1000

2000

3000

4000

5000

1747

380 240180150120

Sig

na

l Inte

nsi

ty (

arb

. un

its)


0

4000

8000

12000

16000

1760S

ign

al I

nte

nsi

ty (

arb

. u

nits

)


120 150 180 240 380 0

2000

4000

6000

8000

1750

120 150 180 240 380

Sig

na

l In

ten

sity

(a

rb.

un

its)


0

4000

8000

12000

16000

1751

120 150 180 240 380


Sig

na

l Inte

nsi

ty (

arb

. un

its)

0

1000

2000

3000

4000

5000

6000

1762

380 240180150120

Sig

na

l Inte

nsi

ty (

arb

.u.)


0

4000

8000

12000

1749

380 240180150120

Sig

na

l In

ten

sity

(a

rb.

un

its)


0

2000

4000

6000

1759

380 240180150120


Sig

na

l In

ten

sity

(a

rb.

un

its)

0

4000

8000

12000

16000

Sig

na

l In

ten

sity

(a

rb.

un

its)


1761

380 2401801501200

2000

4000

6000

8000

10000

12000

1758

150120 180 240 380

Sig

na

l In

ten

sity

(a

rb. u

nits

)


0

2000

4000

6000

8000

10000

12000

14000

16000

1756

380 240180150120

Sig

na

l In

ten

sity

(a

rb.

un

its)


0

2000

4000

6000

8000

10000

12000

14000

16000


Sig

na

l In

ten

sity

(a

rb.u

.)

1757

380 240180150120

0

2000

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10000

12000

14000

1766

380 240180150120

Sig

na

l In

ten

sity

(a

rb.u

.)


0

5000

10000

15000

20000

25000

1755

380 240180150120

Sig

na

l In

ten

sity

(a

rb.u

.)


0

2000

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6000

8000

10000

12000

Sig

na

l In

ten

sity

(a

rb.u

.)


1753

380 240180150120

Mononenergetic Peaks at 380 MeV,

Mononenergetic Peaks at 210 MeV

SD in Energy is 40 MeV

Mean Energy is 255 MeV

Most frequent Energy is 240 MeV

For 20 Shots

At -200 m detuning


0

2000

4000

6000

8000

1763

Sig

na

l In

ten

sity

(a

rb.

un

its)

120 150 180 240 380


This is a Stable “Electron Beam Accelerator”

An initially non-relativistic interaction

producing highly relativistic electron beams

Laser pulse length 74 fs (asymmetric)

(Intensity 7.5 ×1017 W/cm2

(Non-relativistic ) a0 = 0.59).





0

4000

8000

12000

16000

1760

Sig

na

l In

ten

sity (

arb

. u

nits)


120 150 180 240 380

300 MeV per 3 mm 1 GeV per cm

(Nature Physics 2008)

0 100 200 300 400 500 600 70010

100

1000

Wa

vele

ng

th (

nm

)

Electron Beam Energy (MeV)

B

Undulator Parameters

Type Helical

Field Strength 0.5 Tesla

Length 95 cm

Period 2.4 cm

22

2

2 21

2

K

n

u

Undulator was designed through collaboration with KAERI, Quantum Optics Division

Magnet

Gas

Jet

~ 2m

Lanex

LanexLanex

Spectrometer

Gas Density = 1 atm

Laser Height = 3.25 mm

Laser ~ 12 TW, 74 fs

Grating Detuning = 200 m

Beam Profile

After Undulator

e-

UV-IR

Beam Profile

Before Undulator

Energy Spectrum

Undulator

Preliminary Undulator Experiment September 2009

Preliminary Undulator Experiment September 2009

43200 300 400 500 600 700 8000

5

10

15

20

2382

2394

2395

Inte

nsi

ty (

arb

. u

nits

)

wavelength (nm)

170 MeV

# 2382

~ 180 MeV

Beam Energy

# 2395

200 300 400 500 600 700 800

-0.5

0.0

0.5

1.0

1.5

2.0

Inte

nsi

ty (

arb

. u

nits

)

Wavelength (nm)

2356

2363

2365

# 2356

~ 170 MeV ~ 170 MeV

# 2365

Summary and Conclusion

- Using 2 TW class laser and 800 um gas jet we generated 5 MeV

quasimonoenergetic electron beam.

- Using 1 cm gas jet and < 50 TW, we have produced GeV-class

electron beams.

- By sing asymmetric laser pulses and low plasma density, we could

stabilize the electron beam pointing angle and produce highly

relativistic electron beam despite the fact that initial interaction

conditions were not relativistic.

- We have performed preliminary undulator radiation experiment

using 1 m helical undulator.

Dr. T. J. Yu (Laser)

Dr. V. Kulagin, and Uhm (Theory),

Dr. J. Lee (PI),

Dr. H. Suk (Capillary),

Dr. M. S. Hur and Dr. H. J. Lee (Simulations)

Acknowledgement

J. R. Cary (Univ. of Colorado)-Vorpal code

T. Hosokai (Tokyo Inst.Tech)-Gas jet

In Korea

Outside Korea

Thank you

recent progress in laser wakefield acceleration experiments...

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