1. The Cockcroft Institute
The ALPHA-X Project
Mark Wiggins
Technical Manager
The Cockcroft Institute

2. Contents Introduction to the ALPHA-X project
Achievements to date in laser-plasma acceleration
Future plans in current phase and next phase
ALPHA-X Beam Line – still under construction (nearly ready!)
Numerical simulations
Facility experiments
Rutherford Appleton Lab
Friedrich-Schiller-University Jena, Germany
Lund Laser Centre, Sweden
L.Berkeley N.L., USA

3. ALPHA-X Basic Technology Project
Advanced Laser Plasma High-energy Accelerators towards X-rays
Consortium of 7 U.K. research teams U.
Strathclyde
D. Jaroszynski
Imperial
College
Z. Najmudin
U. Abertay
Dundee
A. MacLeod U.
St. Andrews
A. Cairns U.
Oxford
S. Hooker U.
Dundee
A. Gillespie
Rutherford App. Lab.
Daresbury Lab.
P. Norreys & M. Poole
>20 national & international collaborating groups
First phase (extended through Feb 2007)
Funding secured for next phase (EPSRC, 4 years)

4. Project Goals
A programme to investigate laser-plasma acceleration of electrons.
A source of ultra-short, coherent, short-wavelength pulses of radiation.
Allows high-resolution time-resolved experiments in physics, chemistry
and biology.
Motivated by…
Very large acceleration gradients in wakefield accelerators (1 GeV/cm).
Conventional RF accelerators (1 MeV/cm).
Potential for compact, high-energy electron (and other particle) sources
and short-wavelength radiation sources
& much cheaper!
Revolutionary technique

5. Beam Line  e- UV fs laser plasma channel undulator photoinjector RF
10MW
20TW fs laser
plasma channel
undulator
photoinjector
RF Photoinjector
electron bunch production
6.3MeV, 100fs, 100pC
Brookhaven N.L.
T.U. Eindhoven
LAL Orsay (Terry Garvey)
Oxford
Plasma Channel
wakefield accelerator
100MeV – 1GeV electrons
D.L. ASTeC
(Jim Clarke,
Ben Shepherd)
Undulator
coherent radiation pulses
 down to ~ 3nm

6. Laser Wakefield Acceleration
Electrons are accelerated in the wakefield if their initial velocity is sufficiently close to the phase velocity of the wakefield for trapping to occur vg vz
2-D example (A. Reitsma) e.g. PRL 94, (2005).
X [mm]
Ln g
(z-vt)
(z-vt)

7. Achievements - simulations
Long electron bunch simulations (simple model – de Loos & van der Geer)
General
Particle
Tracer
code

8. Achievements - simulations
Electron distribution at capillary entrance (from photoinjector)
Flat cathode
Curved cathode
de Loos et al. PRST-AB (accepted for publication)

9. Achievements – external experiments
Quasi-monoenergetic electron bunches from plasma accelerator
Mangles et al., Nature 431, 535 (2004).
RAL ASTRA laser (40fs, 0.5J)
All-optical injection (electrons
from background plasma)
Supersonic gas jet

10. Achievements – external experiments
(a) At FSU Jena (Strath.) 47MeV, dg/g ~3% PRL 96, (2006).
(b) At LLC (Imperial) 150MeV, dg/g ~3% PRL 96, (2006).
(c) At LBNL (Oxford) 1GeV (capillary), dg/g ~3% Nature Phys 2, 696 (2006).
(a)
Tremendous results!
charge (10s pC)
peak current (kA)
divergence (few mrad)
Beam quality improving
all the time
(b)
(c)

11. Future plans - immediate
First operation of Beam Line
• laser only with gas jet, capillary
• RF photoinjector
Undulator
• electrons from plasma accelerator
• generation of UV radiation pulses
• preliminary studies made at RAL, Jena
Fundamental FEL Equation
Electron E [MeV]
Radiation  [nm] 50
846
100
211
500 8
[u = 15mm, au = 0.8]

12. Future plans – next phase
Wakefield Acceleration
External injection of ultra-short electron bunches from RF gun
Two-stage system
1st stage: bunch compression
2nd stage: acceleration
Structured capillaries
tapered
stepped
undulated
Plasma undulator
u ~ 10s or 100s of microns (compact!)

13. Future plans – next phase
Coherent Radiation Sources
THz pulses (coherent transition radiation)
Backscattering off plasma wakes & ionisation fronts
Short bunch injection in undulator
FEL Amplifier
FEL gain parameter  is a function of
energy (-1)
peak current (I1/3)
emittance (-1/3)
 ~ for ALPHA-X parameters (500MeV electrons)
Need / < 2 for reasonable gain i.e. /  0.6%

14. Future plans – next phase
Stimulated FEL emission ~106 greater than spontaneous emission
Great rewards if you can achieve it!
Peak brilliance »1020 photons / s / 0.1% BW / mrad2 / mm2
for realistic ALPHA-X parameters
High-brightness extreme-UV radiation pulses

15. Summary Ambitious project to investigate laser-plasma acceleration
of electrons
Combines
short electron bunch generation & propagation (PI)
wakefield acceleration (LWFA)
amplification of short-wavelength radiation (FEL)
Also
novel ultrafast electron diagnostics
initial applications programme
Strong theoretical programme
Robin Tucker (CI) Bob Bingham (RAL)
Tito Mendonca (IST, Portugal) Pulsar Physics
Gennady Shvets (UT Austin, USA) Alan Cairns (U StA.)

16. Acknowledgements ALPHA-X Consortium Members ALPHA-X Collaborators
Dino Jaroszynski (Director)
Ken Ledingham, Slava Pavlov, Riju Issac, Paul McKenna,
Enrico Brunetti, Bernhard Ersfeld, Albert Reitsma,
Jordan Gallacher, Andrey Lyachev, Richard Shanks, David Carroll
ALPHA-X Consortium Members
Daresbury Lab, Rutherford Appleton Lab, Imperial College, Oxford University,
University of St. Andrews, University of Dundee, University of Abertay-Dundee
ALPHA-X Collaborators
LAL Orsay, Pulsar Physics, U. Twente, T.U. Eindhoven, IST, LBNL, FSU Jena, CLIO, FOM, IAP,
UTA, LPGP, LLC, UCLA, CAS, NRL, T.U. Crete, JINR, USC, U. Milan, R.-U. Bochum, MPI
John Dainton Cockcroft Institute
Robin Tucker Cockcroft Institute & Lancaster University

17. Thank you First phase is funded by the Research Councils UK
Basic Technology Programme