E-164

U C L AP. Muggli, SLAC-DoE, 04/10/03

E-164Presented by

Patrick Muggli

E-162 Collaboration:F.-J. Decker, M. J. Hogan, R. Iverson, C. O’Connell, P. Raimondi, R.H. Siemann, D. Walz

Stanford Linear Accelerator Center

B. Blue, C. E. Clayton, C. Huang, C. Joshi, K. A. Marsh, W. B. Mori

University of California, Los Angeles

T. Katsouleas, S. Lee, P. Muggli

University of Southern California

and E-164+X:+ C. Barnes, P. Emma, P. Krejcik, D. Johnson, W. Lu, E. Oz


Work supported by USDoE #DE-FG03-92ER40745, DE-AC03-76SF00515, #DE-FG03-98DP00211, #DE-FG03-92ER40727, NSF #ECS-9632735, NSF #DMS-9722121.

OUTLINE

• Past year: -E-162, PWFA with long e-, e+ bunches: z≈700 µm

• Next year: -E-164 PWFA with short e- bunches: z≈100 µm

• 5+ years: -E-164 PWFA with ultra-short e- bunches: z≈20 µm-Long term ideas


PLASMA WAKEFIELD EXPERIMENT@ SLAC

3 km e-/e+

LINACFinal Focus Test Beam

3 km for 50 GeV e- and e+ 1 m for 1 GeV?


PLASMA WAKEFIELD (e-)

• Plasma wave/wake excited by a relativistic particle bunch

• Plasma e- expelled by space charge forces => energy loss, focusing (ion channel formation rc≈(nb/ne)1/2r)

• Plasma e- rush back on axis => energy gain

• Plasma Wakefield Accelerator (PWFA) = TransformerBooster for high energy accelerator

++++++++++++++ ++++++++++++++++

----- --- ----------------

---- -----------

-------- ------- -------------------- - -

-

---- - -- ---

------ -- -- ---- - - - - - --

---- - -- - - - --- --

- -- - - - - -

---- - ----

------

electron beam

+ + + + + + + + + + ++ + + + + + + + + + + + + + +

+ + + + + + + + + + + + + + ++ + + + + + + + + + + + + + +-

- --

--- --

Accelerating Decelerating (Ez)

+ + + + + + + + + + + + + + +

+ + + + + + + + + + + + + + +

Focusing (Er)Defocusing

• Linear scaling: Eacc 110(MeV / m)N 2 1010

z / 0.6mm 2 ≈ 1/z2

@ kpez≈√2


• Optical Transition Radiation(OTR)

• CHERENKOV (aerogel)

- Spatial resolution ≈100 µm - Energy resolution ≈30 MeV- Time resolution: ≈1 ps

5 10 15 20 25 30 35 40 45 50

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y

x10 20 30 40 50 60

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30

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y

x

e-,e+

N=21010

z=0.6 mmE=28.5 GeV

IonizingLaser Pulse

(193 nm) Li Plasma

ne≈21014 cm-3

L≈1.4 m

CherenkovRadiator

Streak Camera(1ps resolution)

Bending MagnetX-Ray

Diagnostic

Optical TransitionRadiators Dump

∫Cdt

Quadrupoles

Imaging Spectrometer25 m

EXPERIMENTAL SET UP

IP0:

IP2:

E-157:

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x10 20 30 40 50 60 70 80 90 100

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x

E-162:

- 1:1 imaging, spatial resolution <9 µm


CHANNELING OF e-

OTR Images ≈1m downstream from plasma

• insensitive to ne at matching, stabilize hose instability• Channeling of the beam over 1.4 m or >12

2z2

K 2 2

3

2 0

K pe

2c ne 1/ 2

In an ion channel:

Envelope equation:

K 2 n

ee2

0m

e2c2

2

4

Beam-plasma matching:

• ne, matched =2.51014 cm-3

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0 0.5 1 1.5 2

07250cwMatchedBetatron.graph

Plasma OFFPlasma ONEnvelope Equation Fit

x (

µm

)

Plasma Density (1014 cm-3)

=30 µm

N=4410-5 m-rad

=0.11 m=0

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0 0.5 1 1.5 2

BetaronFitLongBeta.graph

Plasma OFFPlasma ONEnvelope

x (µ

m)

Plasma Density ( cm-3)

L=1.4 m

0=50 µm

N

=1210-5 m-rad

0=1.16 m

0=-0.5

Not matched


DYNAMIC FOCUSING WITHIN e- BUNCH

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-15 -10 -5 0 5 10 15FocusingEnergySpread.graph

Relative Energy (MeV)Gaussian Bunch (a.u)Focusing Field (a.u.)

Rel

ativ

e E

nerg

y (M

eV)

(ps)

• Correlated Energy Spread

Space-Time Correlationafter Energy Dispersion

0

0.05

0.1

0.15

-10 -5 0 5 10

FocusingFieldvariation.graphFocusing FieldGaussian Bunch (a.u.)

Focu

sing

Fie

ld (

MV

/m)

(ps)

1 2 3"Blow-Out" • Channel Formation

Dynamic Focusing

Head

Head


Density (x1014 cm-3)

Beam

Siz

e (

m)

= -3.5 = -2.8 = -2.1 = -1.4

= -0.7 = 0 = 0.7 = 1.4

= 2.1 = 2.8 = 3.5 = 4.2

= Blowout

= 4.2

= -3.5

= Head

= Middle

DYNAMIC FOCUSING WITHIN e- BUNCH

• Different t or z bunch slices experience a different number of betatron oscillations C. O’Connell et al., PRST-AB (2002)


e-: ne0=21014 cm-3, c/p=375 µm e+: ne0=21012 cm-3, c/p=3750 µm

r=35 µmr=700 µm

• Uniformfocusing force (r,z)

=1.81010

• Non-uniformfocusing force (r,z)

d=2 mm

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

BlowOut

3 beamFront

Back

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

30 beamFront

Back

3-D QuickPIC simulations, plasma e- density:e- & e+ BEAM NEUTRALIZATION

e- e+


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122300cs-qdTriangxyNe.graph

x-Plasma OFFx-Plasma ONy-Plasma OFFy-Plasma ON

FW

HM

Tria

ngle

OT

R (

µm

)

ne (1014 cm-3)

FOCUSING OF e-/e+: HIGH ne

• from OTR images ≈1m from plasma exit

• Focusing limited by emittance growth due to plasma focusing aberrations?

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0 0.5 1 1.5 2

BetaronFitLongBeta.graph

Plasma OFFPlasma ONEnvelope

x (µ

m)

Plasma Density ( cm-3)

L=1.4 m

0=50 µm

N

=1210-5 m-rad

0=1.16 m

0=-0.5

for e-:

M.J. Hogan et al., PRL (2003)


FOCUSING OF e-/e+

0 50 100 150 200 250 300 350 400 450 500

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e-

e+

ne=0 ne≈1014 cm-3

2mm

2mm

• Ideal Plasma Lens in Blow-Out Regime

• Plasma Lens with Aberrations

• OTR images ≈1m from plasma exit (x≠y)


EXPECTED ENERGY LOSS/GAIN, e-

• Expected energy gain < incoming correlated energy spread => need time discrimination

• Expected energy gain: 260 MeV (average), 335 MeV (peak)

• Expected energy loss: 95 MeV (average)

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-8 -6 -4 -2 0 2 4 6 8SimualtionE(z).graph

(ps)

Front Back

Emax

Emin

Eav

2-D OSIRIS PIC simulation: L=1.4 m, ne=1.51014 cm-3, z=40 µm

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0

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-15 -10 -5 0 5 10 15CorrelatedEnergy.graph

Relative Energy (MeV)Gaussian Bunch (a.u.)Longitudinal E-Field (a.u.)

Rel

ativ

e E

nerg

y (M

eV)

(ps)

Head

fp=110 GHz @ ne=1.51014 cm-3


ENERGY GAIN/LOSS AVERAGE, e-

• Average energy gain (slice average): 156 ±40 MeV (≈3107 e-)• Average energy loss (slice average): 159±40 MeV

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SliceEnergyGain3curves.graph

ne=1.61014 (cm-3)

ne=2.01014 (cm-3)

ne=(2.3±0.1)1014 (cm-3)

Rel

ativ

e E

nerg

y (M

eV)

(ps)

+z

+2z

+3z

-2z

-z

ps slice analysis results

• Events/particles to more than 250 MeV


Very Little Energy Spread

e+- beam:E 28.5 GeVN 1.21010 e+

z 0.73 mmr 40 µmrN 1210-5 m rad

Design Charge:21010

Ene

rgy

Spr

ead≈

1.5%

E

x

Low Charge: 1.21010

E

x

ENERGY LOSS/GAIN LOW CHARGE, e+

Cerenkov images => energy spectrum

• Lower charge allows for better time dispersed energy measurements


ENERGY LOSS/GAIN LOW CHARGE e+

• Excellent agreement!

Plasma Off

Front Back

ne=1.81014cm-3

Loss Gain

Front Back

ne=1.81014cm-3

Experiment 2-D SimulationN=1.21010 e+

• Loss ≈ 50 MeV

• Gain ≈ 75 MeV

• Loss ≈ 45 MeV/m 1.4 m=63 MeV

• Gain ≈ 60 MeV/m 1.4 m=84 MeV

B. Blue et al., submitted to PRL


0.01

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E_useful [GV/m]

E_decel [GV/m]

E_spike [GV/m]

Ez [G

V/m

]

z [µm]

N = 1010

e-/bunch, r=10,20 µm

E-1

62E

-157

E-1

64

E-1

64X

NUMERICAL SIMULATIONS: E-164/X , e-

• E-164X: z=20-10 µm: >10 GV/m acceleration! (r dependent!)• Plasma length, energy gain limited by FFTB dump line acceptance

0.2 GV/m4.343106

fp=2.8 THz, W=3MT/m @ ne=1017 cm-3


E-164: RIGHT NOW!

• Goal: >1 GeV over 30 cm (4 GeV/m)• Plasma length, energy gain limited by FFTB dump line acceptance

fp≈700 GHz, W=3MT/m @ ne=51015 cm-3

Beam tuning set up Lithium plasma source

OTRs at plasma entrance/exit UV-photo-ionized plasma


E-164X: BEAM-IONIZED PLASMA

• Plasma source: neL limited by laser fluence and absorption

1010

1011

1012

1013

1014

1015

1016

1017

0 200 400 600 800 1000

VaporPressureLiCs.graph

Temperature (K)

Cesium Lithium

• Relativistic plasma electrons=> ne > given by kpz≈√2 ne≈1016-1017 cm-3

• Short bunch, Er≈5.210-19N/z r (GV/m) > tunneling field (Kyldish, ADK)

• Channeling+long plasma+large gradient=large energy gain!

N=1010 e-, z=r=20 µm in Cs

• Plasma density = neutral density (nf=1), easier, more stable!

Vapor pressure curves


• Propagation in long field ionized plasmas, large energy gains

• Two-bunch experiments: - wake loading(ORION) - beam quality (, ∆E/E, ...)

• ... “Pre-After-Burner”

5+ YEARS

• Stability against hose the instability


• Wealth of important results: - Beam refraction, Muggli et al., Nature 2001- Electrons transverse dynamics, Clayton et al., PRL 2002 - High brightness X-ray emission, Wang et al., PRL2002- Focusing dynamics, O’Connell et al., PRSTAB 2002- Positrons dynamic focusing, Hogan et al., PRL 2003- Acceleration of positrons, Blue et al., submitted to PRL - Acceleration of electrons, Muggli et al., in preparation

• E-157/162 built a PWFA laboratory for 30 GeV beams

• E-164: 1 GeV energy gain over 30 cm, PWFA z scaling law

• E-164X: Ultra short bunches, ultra-high gradients in field-ionized plasmas

SUMMARY

• Two-bunch experiments, hose instability, ultra-high energy gains, after-burner.

Documents

E-164