1. E-164 E-162 Collaboration: and E-164+X:
Presented 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

2. OUTLINE • Past year: -E-162, PWFA with long e-, e+ bunches: sz≈700 µm
• Next year: -E-164 PWFA with short e- bunches: sz≈100 µm
• 5+ years: -E-164 PWFA with ultra-short e- bunches: sz≈20 µm
-Long term ideas
Work supported by USDoE #DE-FG03-92ER40745, DE-AC03-76SF00515, #DE-FG03-98DP00211, #DE-FG03-92ER40727, NSF #ECS , NSF #DMS

3. PLASMA WAKEFIELD EXPERIMENT
@ SLAC
3 km for 50 GeV e- and e+
1 m for 1 GeV?
3 km e-/e+
LINAC
Final Focus
Test Beam

4. PLASMA WAKEFIELD (e-) - +
electron beam
Accelerating
Decelerating (Ez)
Focusing (Er)
Defocusing
• 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)1/2sr)
• Plasma e- rush back on axis => energy gain
• Linear scaling:
≈ 1/sz2
@ kpesz≈√2
• Plasma Wakefield Accelerator (PWFA) = Transformer
Booster for high energy accelerator

5. EXPERIMENTAL SET UP E-157: E-162: e-,e+ IP0: IP2:
sz=0.6 mm
E=28.5 GeV
Ionizing
Laser Pulse
(193 nm)
Li Plasma
ne≈21014 cm-3
L≈1.4 m
Cherenkov
Radiator
Streak Camera
(1ps resolution)
Bending Magnet
X-Ray
Diagnostic
Optical Transition
Radiators
Dump
∫Cdt
Quadrupoles
Imaging Spectrometer
25 m
IP0:
IP2:
• Optical Transition Radiation
(OTR)
• CHERENKOV (aerogel)
E-157:
y,E x
y,E x
E-162: y x y x
- 1:1 imaging, spatial resolution <9 µm
- Spatial resolution ≈100 µm
- Energy resolution ≈30 MeV
- Time resolution: ≈1 ps

6. OTR Images ≈1m downstream from plasma
CHANNELING OF e-
OTR Images ≈1m downstream from plasma
Envelope equation:
In an ion channel:
Beam-plasma matching:
Not matched
• ne, matched =2.51014 cm-3
• s insensitive to ne at matching, stabilize hose instability
• Channeling of the beam over 1.4 m or >12b0

7. DYNAMIC FOCUSING WITHIN e- BUNCH
Head
• Channel Formation ß
Dynamic Focusing
Head
• Correlated Energy Spread ß
Space-Time Correlation
after Energy Dispersion

8. DYNAMIC FOCUSING WITHIN e- BUNCH
Density (x1014 cm-3)
Beam Size (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
= Head
= Middle
• Different t or z bunch slices experience a different number of betatron oscillations
C. O’Connell et al., PRST-AB (2002)

9. e- & e+ BEAM NEUTRALIZATION
3-D QuickPIC simulations, plasma e- density: e- e+
sr=35 µm
sr=700 µm
N=1.81010
d=2 mm
e-: ne0=21014 cm-3, c/wp=375 µm
e+: ne0=21012 cm-3, c/wp=3750 µm
Blow
Out
3s0 beam
Front
Back
3s0 beam
Front
Back
• Uniform
focusing force (r,z)
• Non-uniform
focusing force (r,z)

10. FOCUSING OF e-/e+: HIGH ne
• from OTR images ≈1m from plasma exit
for e-:
• Focusing limited by emittance growth due to plasma focusing aberrations?
M.J. Hogan et al., PRL (2003)

11. FOCUSING OF e-/e+ e- e+ • OTR images ≈1m from plasma exit (ex≠ey) ne=0
ne≈1014 cm-3
2mm
• Ideal Plasma Lens in Blow-Out Regime
• Plasma Lens with Aberrations

12. EXPECTED ENERGY LOSS/GAIN, e-
2-D OSIRIS PIC simulation: L=1.4 m, ne=1.51014 cm-3, sz=40 µm
fp=110 ne=1.51014 cm-3
• Expected energy loss: 95 MeV (average)
• Expected energy gain: 260 MeV (average), 335 MeV (peak)
• Expected energy gain < incoming correlated energy spread
=> need time discrimination

13. ENERGY GAIN/LOSS AVERAGE, e-
ps slice analysis results
• Average energy loss (slice average): 159±40 MeV
• Average energy gain (slice average): 156 ±40 MeV (≈3107 e-)
• Events/particles to more than 250 MeV

14. ENERGY LOSS/GAIN LOW CHARGE, e+
Cerenkov images => energy spectrum
Design Charge:21010
Energy Spread≈1.5% E x
Low Charge: 1.21010 E x
e+- beam:
E GeV
N 1.21010 e+
sz mm
sr 40 µm
erN 1210-5 m rad
Very Little
Energy Spread
• Lower charge allows for better time dispersed energy measurements

15. ENERGY LOSS/GAIN LOW CHARGE e+
Experiment
2-D Simulation
Plasma Off
Front
Back
ne=1.81014cm-3
Loss
Gain
Front
Back
ne=1.81014cm-3
• Loss ≈ 50 MeV
• Loss ≈ 45 MeV/m  1.4 m=63 MeV
• Gain ≈ 75 MeV
• Gain ≈ 60 MeV/m  1.4 m=84 MeV
• Excellent agreement!
B. Blue et al., submitted to PRL

16. NUMERICAL SIMULATIONS: E-164/X , e-
0.2 GV/m
4.3 43
106
• E-164X: sz=20-10 µm: >10 GV/m acceleration! (sr dependent!)
• Plasma length, energy gain limited by FFTB dump line
acceptance
fp=2.8 THz, ne=1017 cm-3

17. E-164: RIGHT NOW! Beam tuning set up Lithium plasma source
OTRs at plasma entrance/exit
UV-photo-ionized plasma
• Goal: >1 GeV over 30 cm (4 GeV/m)
• Plasma length, energy gain limited by FFTB dump line
acceptance
fp≈700 GHz, ne=51015 cm-3

18. E-164X: BEAM-IONIZED PLASMA
• Plasma source: neL limited by laser fluence and absorption
• Relativistic plasma electrons=> ne > given by kpsz≈√2 ne≈  cm-3
• Short bunch, Er≈5.210-19N/sz sr (GV/m) > tunneling field (Kyldish, ADK)
Vapor pressure curves
N=1010 e-, sz=sr=20 µm in Cs
• Plasma density = neutral density (nf=1), easier, more stable!
• Channeling+long plasma+large gradient=large energy gain!

19. 5+ YEARS
• Propagation in long field ionized plasmas, large energy gains
• Stability against hose the instability
• Two-bunch experiments: - wake loading
(ORION) - beam quality (e, ∆E/E, ...)
• ... “Pre-After-Burner”

20. SUMMARY • E-157/162 built a PWFA laboratory for 30 GeV beams
• 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-164: 1 GeV energy gain over 30 cm, PWFA sz scaling law
• E-164X: Ultra short bunches, ultra-high gradients in field-ionized plasmas
• Two-bunch experiments, hose instability, ultra-high energy gains, after-burner.