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Ultrafast Laser -Driven Wakefield Accelerators Oleg Korovyanko 01/12/2009 SLAC AARD seminar. Outline. Part 1: Wakefield accelerators: techniques to generate short e bunches Part 2: Production of quality electron beams, characterization and applications Part 3: Relevant laser techniques

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Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

Ultrafast Laser

-Driven Wakefield Accelerators

Oleg Korovyanko 01/12/2009SLAC AARD seminar


Outline
Outline

Part 1: Wakefield accelerators: techniques to generate short

e bunches

Part 2: Production of quality electron beams, characterization and applications

Part 3: Relevant laser techniques

Part 4: Conclusion and perspectives


Rf vs plasma

100 mm

Plasma cavity

RF vs Plasma

E-field max~ 10 MeV /m

E-field max~ 10 GeV/m

Courtesy of V. Malka

1 m

RF cavity

DWA

Diel. surface field breaks down @~ 10 GeV/m



Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

> 1.6 W @ 400 nm

SHG2

SHG1

FS

D3-4

IR4

D1

D2

IR1

WP

SHGxtal

THGxtal

> 900 mW @ 266nm

IR2-3

Prepared by DSF2059, 031307, RLS


Anl awa 1 3 ghz tsa 50
ANL AWA1.3 GHz, TSA 50

  • Built as DWA: witness, drive bunches

  • Two 248nm pulses go to photocathode of RF gun, one or several drive bunches

    inter-pulse separation controlled w/ mechanical delay stage 23 cm, ~770ps, or 10.5Lo, Lo=22mm

  • A new UV stretcher utilizes thick BBO crystals in series

  • Laser mode at photocathode: adjustable iris at 1 m from photocathode




Monoenergetic beams from literature
Monoenergetic Beams from Literature

Intensity

tL/Tp

Energy

dE/E

Charge

Ne

[pC]

Article

Name

Lab

3

/cm

x10

W/cm

]

18

2

x1018

[MeV]

[%]

Mangles

Nature (04)

RAL

73

6

22

20

2,5

1,6

Geddes

Nature (04)

L'OASIS

86

2

320

19

11

2,2

Faure

Nature (04)

LOA

170

25

500

6

3

0,7

Hidding

PRL (2006)

JETI

47

9

0,32

40

50

4,6

Hsieh

PRL (2006)

IAMS

55

336

40

2,6

Hosokai

PRE (2006)

U. Tokyo

11,5

10

10

80

22

3,0

Miura

APL (2005)

AIST

7

20

432E-6

130

5

5,1

Hafz

PRE (2006)

KERI

4,3

93

200

28

1

33,4

Mori

ArXiv (06)

JAERI

20

24

0,8

50

0,9

4,5

Mangles

PRL (2006)

Lund LC

150

20

20

5

1,4

State-of-art gradient

27 GeV/m, SLAC, 27 GeV drive, Nature’2007


Towards longer interaction length
Towards longer interaction length

Diffraction length L~pr2/l0Rayleigh

Dephasing length ~ a0 lp3/ l02

Pump depletion length a0 >>1

  • Expanding Bubble Injection regime

    Degrades emittance due to high transverse field – control trapping

Pre-formed channel injection : plasma “fiber”

Optical injection by colliding pulse

Capillary discharge channel


Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

250 mJ, 30 fs ffwhm=30 µm

I ~ 4×1017 W/cm2

a1=0.4

700 mJ, 30 fs, ffwhm=16 µm

I ~ 3×1018 W/cm2

a0=1.2

LOA

Experimental set-up

electron spectrometer

to shadowgraphy

diagnostic

Probe

beam

LANEX

Gas

jet

B Field

Pump beam

Injection beam



Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

-

=

×

18

3

n

1

.

5

10

cm

m

l

=

m

0

.

8

=

m

m

p

w

20

0

t

=

30

fs

f(E) (a.u.)

=

P

200

TW

After 5 Zr / 7.5 mm

=

a

4

0

2.5

2

1.5

1

0.5

0

800

1200

1600

2000

Energy (MeV)

Laser plasma injector :

GeV electron beams

Courtesy of UCLA& Golp groups


Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

Monoenergetic bunch comes from

colliding pulses: polarization test

Parallel

polarization

Crossed

polarization



Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

Cubic dispersion (gratings etc.)

No significance

Quadratic dispersion (glass etc.)

Spectral Phase


Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

Water radiolysis

D.A. Oulianov et al JAPS’ (2007).


Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

  • How to control injection?

    -inject electron beam from LINAC (SLAC, Nature’07)

    ANL LINAC Chuck Jonah, 1988

    21 MeV; 7 ps; 4nC; plasma density 4-7x1010 cm-3

    -use laser-based ionization

    DWA : “chirped” bunches, break down due to CCR multiphoton ionization

  • *control of laser PW, wavelength

  • How to control acceleration?

    -plasma density

    -channel guiding (LBNL)

    -colliding pulse (LOA)


Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

Acousto-optic shaping

Dazzler - from Fastlite

No need for zero dispersion stretcher

Controls different dispersion orders



Injection assisted by laser ionization
Injection assisted by laser ionization

  • Laser-assisted ionization of atoms or ions

  • Two types: multiphoton and Frank-Keldysh tunneling

  • 13.6 eV vs 1.5 eV

  • DFG: Reducing laser frequency increases ponderomotive potential ~w-2

  • HE TOPAS ~100 mJ @ l~9 mm


Laser techniques
Laser techniques

  • Multi-bunch generation w/ DWA

  • Pulse shaping

  • DFG due to detuned from 800 synchronized Regen pulses

  • Atto-second science: CEP


Applications conclusions and perspectives
Applications,Conclusions and Perspectives

DW should be 7.2 GeV with laser parameters (100TW, a0 ~3, Li~3.8cm)

  • THz source CCR

  • Hard X-ray fs source

  • X-ray free electron lasers

  • Radiology, biophysics around water window

  • Early stage of proton acceleration

  • 1TeV is a goal for HE physics is too far

    32 kJ of laser energy (100 lasers of 300J)

  • Optical Parametric CPA


Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar



Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar

Background. Parametric interaction

wp = ws + wi

phase matching conditions in a uniaxial x-stal such as BBO

kp = ks + ki

Non-collinear

Each photon in idler beam generated together with a photon in signal beam

S P

I II P


Ultrafast laser driven wakefield accelerators oleg korovyanko 01 12 2009 slac aard seminar
PW

Spectral Phase

Cubic dispersion (gratings etc.)

No significance

Quadratic dispersion (glass etc.)


Frogs
FROGs

  • Frequency Resolved Optical Gating (Kane and Trebino’ Opt Lett’ 1993)

  • Suitable for single-shot detection

  • Not an interferometric technique, just 2D spectrogram of cross-correlation function

  • Not easy to reconstruct E(w,t): iterative algorithm, t-direction ambiguity

  • Slight modification (Masalov et al, JOSA 2001) makes use of spatial interferometry

wavelength

slit

2nd harmonic

Doubling x-stal

t



Spider
SPIDER

c2

2p/t

  • Spectral phase interferometry for direct electric-field reconstruction (Iaconis and Walmsley, Opt Lett. ‘ 1998)

  • Spectral interferogram of two frequency-shifted up-converted pulses; no reference needed

  • Non-iterative reconstruction algorithm; 1D data set

t~2 ps

t

w