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

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

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)

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

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

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, 085004 (2005). X [mm] Ln g (z-vt) (z-vt)

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

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

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

Achievements – external experiments (a) At FSU Jena (Strath.) 47MeV, dg/g ~3% PRL 96, 105004 (2006). (b) At LLC (Imperial) 150MeV, dg/g ~3% PRL 96, 215001 (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)

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]

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!)

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)  ~ 0.003 for ALPHA-X parameters (500MeV electrons) Need / < 2 for reasonable gain i.e. /  0.6%

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

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.)

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

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