Plasma Wakefield Acceleration at VELACLARA Facility Guoxing Xia

Plasma Wakefield Acceleration at VELA/CLARA Facility Guoxing Xia University of Manchester and Cockcroft Institute 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 1

Outline ² VELA/CLARA facility ² PWFA research at Daresbury lab ² Simulation results ² Plasma source R&D ² Summary 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 2

VELA (Versatile Electron Linear Accelerator) VELA Specification Beam Energy 4 - 6 Me. V Bunch Charge 10 - 250 p. C Bunch length (σ t, rms) 1 – 10 ps Normalised emittance 1 - 4 µm Beam size (σx, y, rms) 0. 5 - 5 mm Energy spread (σe, rms) 1– 5% Bunch repetition rate 1 – 10 Hz *Not all parameters achievable simultaneously Notes: 1. VELA gun is from Strathclyde (ALPHA-X) 2. Max rep rate is 10 Hz but laser and RF capable of 400 Hz 3. 400 Hz gun under development at Daresbury 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 3

CLARA Compact Linear Accelerator for Research and Applications An upgrade of the existing VELA Photoinjector Facility at Daresbury Laboratory to a 250 Me. V Free-Electron Laser Test Facility Proof-of-principle demonstrations of novel FEL concepts Emphasis is ULTRA-SHORT PULSE GENERATION ASTe. C Strathclyde INFN Frascati Swiss. FEL DLS Oxford Liverpool Manchester Imperial 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 4

CLARA Layout FEL OUTPUT STUDIED A M LAS E LIN T S TE EN P The existing VELA RF Photoinjector Facility ED AT UL L CE C SA ON D TE A ER D AN IP AN M ERA FEL TG PU T OU TED INT ER AC T IO N BE S W AM ITH S LA SE R R CT LE E EL GE EC NE TR RA ON TE S D HE 24/09/2020 RE EAAC 2015, 13 -19 September, Elba, Italy 5

CLARA beam parameters CLARA CDR, July 2013 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 6

Other goals and benefits of CLARA • • • ASTe. C CERN FERMI@Elettra RHUL INFN Frascati Swiss. FEL DLS Lancaster INR Moscow The opportunity for R&D on advanced technologies: – New photoinjector technologies – Novel undulators (short period, cryogenic, superconducting…. ) – New accelerating structures: X-Band etc. . . – Advanced diagnostics The enhancement of VELA beam power and repetition rate, enabling additional industrial applications. The possibility to use the electron beam for other scientific research applications: R ES ) G N GE N O C N O A I O T R A TI ) UR L, … TR ER S O R A C O T T M S EL S LE LE N ER Z, … AT EA N E F L E H C O C I O S AB TO UR CC RC CE , TH ST CT S G O N A C P A E A M A A LA E PH ITHTO AM YP RIN AF FR L MA ES D P L T R E S F R V A, A VE , SM LT DI OM R G EL O L W U O C V P N O R D N D F ( NO (C ASTe. C RHUL Oxford 24/09/2020 ASTe. C Strathclyde Manchester INFN Frascati ASTe. C York Swansea UCL ASTe. C RHUL Liverpool EAAC 2015, 13 -19 September, Elba, Italy Lancaster Manchester Oxford 7

CLARA Status • • JINST 9 (2014) T 05001 • • 24/09/2020 The CDR was published in July 2013 Swiss. FEL are providing required 3 linacs, together with a number of quadrupoles and solenoids (Q 4 2014) The project has now been split into Two Phases PHASE 1 – Front End, 50 Me. V – This is happening now, with procurement progressing, and installation in 2015. – Will enable access to bright, short, up to ~50 Me. V electron bunches for UK accelerator science and technology community – Will enable new high rep rate photoinjector to be characterised with beam whilst VELA/CLARA Phase 1 still operational (i. e. two guns) – Potential for early exploitation of 20 TW laser PHASE 2 a – 150 Me. V, up to bunch compression section – Funded, procurement starting this year PHASE 2 b – 250 Me. V FEL Test Facility – Not Yet Funded – Part of Ongoing UK Capital Consultation Exercise – CLARA is a priority for STFC EAAC 2015, 13 -19 September, Elba, Italy 8

VELA + CLARA Phase 1 (2015) ~50 Me. V Phase 1 parameters: Max Energy Max Charge Norm. Emitt. Min Bunch Length Max Peak Current Bunches/RF pulse Pulse Rep Rate ~50 Me. V 250 p. C <1 mm mrad 50 fs (rms), (10 Me. V) 2 k. A 1 10 Hz (400 Hz later) ~5 Me. V 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 9

Why PWFA at Daresbury • VELA beam is ready for use as the first PWFA experiment test - August 2015 • CLARA front-end beam (up to 55 Me. V) will be available in October 2016 • First UK-based PWFA experiment • Why it makes sense – Free space available close to VELA/CLARA beam line – Unique beam properties (low emittance, high charge, relativistic) – Diverse beam operation modes – Well developed beam diagnostic equipment for VELA and CLARA (deflecting cavities, longitudinal bunch length measurement, etc. ) • Contributions to advanced accelerator community – Two-bunch experiment for energy boost of CLARA beam and beam quality preservation – Plasma lens focusing effect—first experiment done last month – Beam loading effect for PWFA—See K. Hanahoe’s poster on Wednesday – Hybrid wakefield acceleration/plasma photocathode injector—See B. Hidding’s talk on Wednesday/A. Knetsch’s poster on Monday – High transformer ratio (via laser shaping of the e- bunch density profile) 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 10

Plasma accelerator research station (PARS) 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 11

Plasma Accelerator Research Station-PARS Three regimes of CLARA 12

Goals for PARS • A dedicated, multifunctional platform (a small scale) to study the key issues in novel accelerators (PWFA, LWFA and DLA) • We aim to demonstrate the high gradient acceleration of a single e- bunch and two bunch acceleration for preserving the high beam quality (low emittance, low energy spread) for the first instance • Other novel injection scheme experiments will be followed , e. g. trojan-horse, ionization injection, etc 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 13

CLARA PARS Project Work packages: • Electron Beam Delivery (design, operation and optimization of electron beam to the PARS; dogleg, final focus, e- beam dump, laser beam dump)—design work mostly done. • Plasma Source (produce a 5 -200 mm long discharge plasma source with diameter of ~1 mm, density of 1014 -1017 cm-3, plasma density measurement)---funding secured, ongoing work. • Beam Diagnostics (measurement of beam specifications before and after plasma, emittance, energy, beam size, bunch length, charge, etc. energy spectrometer, CTR, OTR, streak camera, ICT, etc. )---ongoing work. • Simulations (electron beam simulation, PIC simulation of interactions between plasma and beam, code benchmarking, optimize beam and plasma parameters for proposed scenarios)---ongoing work. 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 14

PARS beam line design VELA PARS at CLARA 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy (D. Angal-Kalinin) 15

Roughly 18 m beam transport line With beam matching prior to plasma 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 16

Simulation results for single bunch Simulations were performed by using VSIM by Tech-X. O. Mete et al. , to be submitted. 17

Simulation results for two bunches initial bunches after 0. 5 m O. Mete et al. , to be submitted. Beam loading for optimisation of witness energy spread and transformer ratio. 18

CLARA front-end 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 19

CLARA front-end Bunch length: 75 μm, beam radius: 20 μm, beam energy: 30 Me. V, bunch charge: 250 p. C, plasma density: 3 E 15 /cm^3 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 20

Plasma lens Simulation studies of an overdense plasma lens using the VELA electron beam Coffin with laserionized gas jet and diagnostics VELA: 4. 8 Me. V σz = 3. 3 mm σr = 0. 45 mm Average focusing gradient of 10 T/m z = 0 z = 14. 5 cm 2 D bunch density profile at different z values, longitudinal aberration causes different focusing strength along the bunch z = 35 cm

Plasma Source R &D C Electrical feedthrough Earth electrode Cathode Earth electrode vvvv Vacuum flange R 2 vvvv HV R 1 Thyratron Observation window Vacuum chamber Ion pump Gauge Gas Inlet Polyether ketone (PEEK) insulators 22

Plasma source R&D 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 23

Summary • A dedicated, multi-functional PARS facility at VELA/CLARA will be the UK based novel acceleration research facility • The high gradient acceleration, preservation of the high beam quality on the plasma wakefield acceleration will be studied soon • Novel injection schemes, beam dynamics (e. g. CSR), advanced diagnostics will be tested in this facility • We welcome the colleagues in the community to test their ideas at PARS in Daresbury lab. 24

Acknowledgements ASTe. C colleagues: J. Clarke, D. Angal-Kalinin, J. Jones, P. H. Williams, J. W. Mckenzie, B. L. Militsyn… Our group in Manchester O. Mete, H. Kieran, T. Pacey, Y. Li, M. Wigram, M. Dover, J. Zhang, J. Wright, G. Xia Strathclyde University B. Hidding’s group Tech-X UK Ltd. J. Smith 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 25

Thanks for your attention! 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 26

Advert • • Professor or Reader in Novel Methods of Particle Acceleration Lancaster University - Physics Location: Lancaster Salary: £ 48, 743 to £ 61, 741 Hours: Full Time Contract Type: Permanent Placed on: 6 th August 2015 Closes: 30 th September 2015 Job Ref: A 1339 Salary: Professor (minimum £ 61, 741) – pay award pending Reader £ 48, 743 - £ 54, 841 – pay award pending Interview Date: 18 November 2015 The Cockcroft Institute, a unique collaboration between the Universities of Lancaster, Liverpool, Manchester and Strathclyde, the Science and Technology Facilities Council and industry brings together the best accelerator scientists, engineers, educators and industrialists to conceive, design, construct and use innovative instruments of discovery and to lead the UKs participation in flagship international experiments. The Institute has been involved in the development of the UKs first Free Electron Laser (FEL) on the ALICE accelerator test facility and is contributing towards development of an ambitious FEL test facility (CLARA) to advance worldwide FEL research. It has a strong collaboration with CERN in the areas of LHC and its various upgrades, anti-matter research and future developments in high energy accelerators, including the AWAKE experiment for proton driven plasma wake field acceleration, and with the ESS at Lund. It is also developing a stronger relationship with the University of Strathclyde and their laser driven plasma acceleration facility, SCAPA. The Institute is housed in a dedicated building adjacent to the Daresbury Laboratory, one of the two major national accelerator laboratories in the UK. 24/09/2020 EAAC 2015, 13 -19 September, Elba, Italy 27