1. ERLP Overview Hywel Owen ASTeC Daresbury Laboratory

2. Light Source Hierarchy First generation - parasitic SR beamlines on high-energy physics accelerators; e.g. the SRF on NINA. Second generation - dedicated particle accelerators providing synchrotron radiation from bending (dipole) magnets. Third generation - dedicated particle accelerators providing synchrotron radiation from special magnets (insertion devices) placed between the dipole magnets. Fourth generation - FEL-based (could be linac, storage ring)

3. The Solution - a Linac-Based Light Source Linac can deliver a very high quality electron beam (now) Electrons are required only once then dumped. Temporal pulse pattern flexibility. Features: High average brightness gun. Normal or superconducting linear accelerator. One or more FELs. Energy Recovery required for economy (55 MW power in 4GLS CW branch).

4. ERLP - A Prototype Accelerator for 4GLS EMMA For more information, and Conceptual Report, See www.4gls.ac.uk

5. electrons anode ERLP DC Electron Gun Electrons XHV Ceramic Cathode SF6 Vessel removed Cathode ball Stem laser Anode Plate

6. Text Glassman PK500N008GD5 Voltage-500 kV Current8 mA Cockcroft-Walton based multiplier Delivered December 2003 Gun Power Supply

7. Superconducting Modules Delivery April/July 2006 JLab HOM coupler design adopted for the LINAC module 2 x Stanford/Rossendorf cryomodules – 1 Booster and 1 Main LINAC. Booster module: 4 MV/m gradient 32 kW RF power Main LINAC module: 14 MV/m gradient 16 kW RF power

8. ERLP Cavity Test Results Booster Cavity1Linac Cavity1 Booster Cavity2Linac Cavity2 Specification of > 15MV/m at Q o > 5 x 10 9 Goal

9. ERLP as an Injector for EMMA 2 x 1.3 GHz Superconducting Modules

10. ERLP Parameters ParameterValue Nominal Gun Energy350 keV Max. Booster Volts8 MV TL 2 Energy8.33 MeV Max. Linac Volts26.67 MV Max. Energy35 MeV Linac RF Frequency1.300 GHz (+/- 1 MHz) Bunch Repetition Rate81.25 MHz Bunch Spacing12.3 ns Max Bunch Charge80 pC (risk variable) Particles per Bunch5 x 10 8 Bunches per Extraction Energy10 to 20 MeV (need to check lower limit) Extraction Emittance5-20 mm mrad (various issues)

11. ERLP Operating as an Injector for EMMA 8.00 MV (2x4 MV) (standard) 8.35 MeV (standard) 0.35 MeV (fixed) 10-20 MeV (variable) 1.65-11.65 MV (variable) Later we will need to consider adapted injector (post-4GLS construction)

12. Bunch Shapes in ERLP (B.Muratori presentation) Sextupoles also needed in return arc Optimise energy spread after deceleration Allow clean extraction of beam to dump

13. ERLP Laser Paths – Injector, FEL, THz, EO

14. ERLP Photoinjector and Laser LASER ROOM ACCELERATOR HALL Shield wall Optical Table DC Gun Based on Jlab design Commercial 500kV (350kV) 8mA DC Power Supply (Glassman Europe) Power supply and gun enveloped by 0.8 Bar SF6 environment Booster Cavity Laser Beam Transport System

15. ERLP Laser Pulse Output Characteristics Cathode materialCs:GaAs Electron bunch charge80 pC Bunch length20 ps Bunch repetition rate81.25 MHz Pulse train length 1 bunch and 20-100  s Pulse train repetition rateSingle shot and 1-20 Hz Cathode efficiency1 %1 % Laser wavelength532 nm Laser pulse energy at cathode20 nJ Average power at cathode<4 mW Pulse length<20 ps Beam diameter at cathode2-6 mm (FWHM) Nd:VanadateLaser material -- -- 81.25 MHz Pulse repetition rate - - Cw mode-locked Pulse train rep. rate - - 1064 / 532 nm Laser wavelength 61.5 nJ 532nm output energy per pulse 5 W Average power 7 ps Pulse length (FWHM) 0.6 mm Beam diameter output The commercial solutionRequirements

16. ERLP Laser

17. Injection and Extraction Timing Structure Standard ERLP injector 12.3 ns bunch spacing Up to ~160 pC per bunch Up to 2 bunches Total charge <0.32 nC Spec is 1 bunch, 80 pC Pulse-stacking (adapted injector) Down to 0.77 ns spacing Up to ~80 pC per bunch Up to 18 bunches Total charge? Costs more! Revolution time 55 ns (16.5 m) rise time fall time Injection flat-top time (top is not really flat) 12.3 ns (81.25 MHz) ~15 ns ~20 ns Revolution time 55 ns (16.5 m) 0.77 ns (1.3 GHz) max. 18 bunches RF frequency in injector can be changed by ~1 MHz – not enough! ~20 ns rise time fall time Injection flat-top time ~15 ns ~20 ns

18. Faro Laser Tracker Repeatability 1  m +1  m /m Accuracy 10  m + 0.8  m /m Uncertainty ≈ 10  m /m Portable Robust Spatial Analyzer Metrology Software Error Simulations Multiple instruments/types Automation ERLP and EMMA Survey – see talk by John Strachan

19. Simulation of reference grid in SA 76 Grid reference points 40 Instrument positions Each point measured by a minimum of 3 instrument locations Faro Tracker Grid reference points ERLP Hall Survey and Alignment

20. Installation Progress Photoinjector laser operating since April ’06 Gun installed with a dedicated gun diagnostic beamline Both superconducting modules delivered from Accel Cryosystem installed and used to cool accelerating modules down to 2K All beam transport modules now installed – one area under vacuum Most hardware components now installed

21. Performance Achieved So Far Gun operating voltage 350 kV (spec value) Output bunch charge 5 pC (target 80 pC) Cathode quantum efficiency In gun: 0.4% In the lab: 3.5% (spec is ~few percent) Bunch train length 100 µs (spec value) Train repetition rate 20 Hz (spec value) ParameterValue Nominal Gun Energy350 keV Max. Booster Volts8 MV TL 2 Energy8.33 MeV Max. Linac Volts26.67 MV Max. Energy35 MeV Linac RF Frequency1.300 GHz Bunch Repetition Rate81.25 MHz Bunch Spacing12.3 ns Max Bunch Charge80 pC Particles per Bunch5 x 10^8 Bunches per Extraction Energy10 to 20 MeV Extraction Emittance5-20 mm mrad 350 keV Test line screen

22. Ongoing Work Cleaning and re-assembly of the gun Understanding and testing the cryogenic system Installation and testing of all RF systems Commissioning of the booster and linac modules BTS Installation/Commissioning Laser room modification to accept the terawatt laser

23. 2007 Schedule Gun & diag line studies finished3 rd April Re-configure booster 16 th April Full BTS Pumpdown25 th April RF Systems ready25 th May Beam through Module 1 (8.35 MeV) June Beam through Module 2 (35 MeV) June onwards Energy recovery demonstrated October Install wiggler Energy recovery from FEL-disrupted beam Produce output from the FEL