Experimental Results of a Plasma Wakefield Accelerator using Multiple Electron Bunches by

Themos Kallos Themos Kallos, Tom Katsouleas, Patric Muggli University of Southern California Los Angeles, CA, USA & Karl Kusche, Jangho Park, Igor Pogorelsky, Daniil Stolyarov, Vitaly Yakimenko Accelerator Test Facility @ Brookhaven National Lab Upton, NY, USA & Wayne D. Kimura STI Optronics, Inc. Bellevue, WA, USA

• Gradient of 35 MeV/m (ILC) 150MeV/m (CLIC)

~10 cm

• Limited e.g. by wall breakdown*

• Plasmas support 10 – 100 GeV/m

*Braun

et al., Phys. Rev. Lett. 2003

Witness e-

~ 100 μm

p 

2 c

p



Electric field

e2 n p

 0 me

ATF

SLAC

• 35 MeV/m over 1.7cm of plasma

Can we multiply the energy?

• 50 GeV/m over 85cm of plasma

(thus reducing the length and cost)

• Energy doubling! (42 GeV84 GeV)

Yakimenko et al., Phys. Rev. Lett. 2003

Blumenfeld et al., Nature 2007

~ 1 cm

• 0.1 – 1 atm H2

• 20 kV charging voltage • Collect light to measure plasma density (Stark Broadening)

1014 – 1018 cm-3

3 – 5 μs duration

Plasma Density [cm-3]

Plasma Density for 10mm capillary [T=2eV, H ] 100Torr 20kV 100Torr 10kV 30Torr 20kV 30Torr 10kV

18

10

17

10

16

10

-0.2

0

0.2 Time [ s]

0.4

0.6

Prima Piatti

λp

λp

Energy

 E   z  R56   E  z 0   z  D Nb  E   x ,mask   E 0  

P. Muggli et al., Phys. Rev. Lett. 2008

Time

Energy • 150-200 pC after the mask • 100 – 300 μm period • Resonant at 1016 – 1017 cm-3

Wakefield Amplitude [MeV/m]

Wakefield and beam density, 4e+017cm -3 400 eBeam Wakefield

200 0 -200 -400

0

0.2

0.4

0.6

0.8

1 Time [ps]

1.2

1.4

1.6

1.8

2

# of particles [100,000 total]

Energy Spectrum after 10mm of plasma 10000 8000 6000 4000 2000 0

54

56

58

60 62 eBeam Energy [MeV]

64

66

68

Wake Amplitude [MeV/m]

140 120

5 Bunches 150pC No mask 300pC

100

20% or ~100ns

80 60 40 20 0 14 10

15

10

16

10 Plasma density [cm-3]

17

10

18

10

Plasma off

Plasma on Shots at 2.368 s or 7.2e+013 cm-3

1.5

Plasma OFF

Wakefield [MeV/m]

Experiment

Wakefield and beam density, 7e+013cm-3 20

Head

0 -20 0

1

0.5

Head 0 58.4

58.6

58.8 59 59.2 59.4 Beam Energy [MeV]

59.6

Beam density [a.u.]

Plasma ON

1

eBeam Wakefield Data

1000

ON

2

3

Time [ps] Energy Spectrum after 6mm of plasma

Simulation

4

5

OFF

500

Head 0 58.5

59 eBeam Energy [MeV]

• whole bunch: 35MeV/m • microbunches: 22MeV/m after 6mm of plasma @ 7x1013 cm-3

59.5

Secondi Piatti

Wakefield [GV/m]

5

R  1.1   10%

8

0

beam

7

wake

-5 0

100

200

300 400 Distance [ m]

500

600

Wakefield [GV/m]

5

R 8   64%

8

0

1

1

1

1

beam wake

-5 0 Laziev et al., EPAC 1988

100

200

300 400 Distance [ m]

500

600

Jing et al., Phys. Rev. Lett. 2007

6

Thank you!