The ALPHA-X Project Mark Wiggins Technical Manager

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

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 Contents • Introduction to the ALPHA-X project • Achievements to date in laser-plasma acceleration • Future plans in current phase and next phase

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 U. Oxford S. Hooker U. St. Andrews A. Cairns • U. Abertay • Dundee • A. MacLeod Rutherford App. Lab. Daresbury Lab. P. Norreys & M. Poole U. Dundee A. Gillespie Imperial College Z. Najmudin • >20 national & international collaborating groups • First phase (extended through Feb 2007) • Funding secured for next phase (EPSRC, 4 years)

Revolutionary technique & much cheaper! 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

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

vg vz 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 • 2-D example (A. Reitsma) e.g. PRL 94, 085004 (2005). Ln g X [mm] (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) Curved cathode Flat 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

(a) (b) (c) 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). • Tremendous results! • charge (10s pC) • peak current (kA) • divergence (few mrad) • Beam quality improving • all the time

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 [u = 15mm, au = 0.8]

Plasma undulator u ~ 10s or 100s of microns (compact!) Future plans – next phase • WakefieldAcceleration • 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

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

Future plans – next phase • Stimulated FEL emission ~106 greater than spontaneous emission • Great rewards if you can achieve it! • Peak brilliance »1020photons / 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 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 DaintonCockcroft Institute • Robin Tucker Cockcroft Institute & Lancaster University

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

The ALPHA-X Project Mark Wiggins Technical Manager