1. James Holloway University College London, London, UK PhD Supervisors: Professor Matthew Wing University College London, London, UK Professor Peter Norreys University of Oxford, Oxfordshire, UK Central Laser Facility, Rutherford Appleton Laboratory, UK Bright Radiation Source based on Plasma-micro-bunched Diamond Beam

2. Image Source: http://www.veqter.co.uk/residual-stress-measurement/synchrotron-diffraction Synchrotron Facilities Worldwide

3. Image Source: http://www.veqter.co.uk/residual-stress-measurement/synchrotron-diffraction Synchrotron Facilities Europe

4. Image Source: http://www.veqter.co.uk/residual-stress-measurement/synchrotron-diffraction Synchrotron Facilities Europe 330 mm 26 mm 14.6 mm 120 mm 52 mm 5.4 mm 2.4 mm 13.2 mm PETRA III Electron beam length Proton beam length

5. Use existing facilities’ beams to drive PWA Accelerate higher energy beams using PWA Generate harder X-rays from 3rd generation light sources The Goal σ ideal = λ p / (π√2) Need beam lengths of: σ z < 1 mm These beams are too long to drive effective wakefields Existing beam lines have limited space Longitudinal compression via magnetic chicanes takes considerable space and expense The Problem Micro-bunch beams to make them an effective wakefield driver The Solution

6. Strong transverse kick from laser wakefield Propagate beam through vacuum Pass micro-bunches into second plasma stage when on-axis number density maximised Micro-Bunching Via Wakefield Kick and Drift Space Long electron beam Led by laser Neutral plasma + + + + + + - - - + Vacuum Micro-bunched driver beam. Second plasma cell

7. Beam number density. 51 mm of propagation E = 300 MeV ε p = 0 σ z = 0.6 cm σ r = √2 / k p Q = 0.1 nC Electron beam n e = 2.84e22 m -3 λ p = 200 um E r = 1 GVm -1 The Plasma

8. 3.5 x 10 19 3.1 x10 19 m -3 On axis number density enhanced by ~ an order of magnitude Beam number density. 51 mm of propagation

10. Diamond Booster Param E = 300 MeV ε p = 0 σ z = 0.6 cm σ r = √2 / k p Q = 0.1 nC Electron beam 2 2 3 3 1 1 First Plasma Cell (3.5 mm) Vacuum (48.5 mm) Second Plasma Cell (> 100 mm) 1) The long beam given transverse momentum by strong wakefield. 2) Micro-bunches form as half e- defocused, other half focused 3) At the moment the beam has achieved best micro-bunching*, pass into the second plasma cell. The ‘Drift Space’ Design First plasma cell analogous to lens Longer first cell results in a stronger focus and shorter vacuum needed However strong focus results in higher emittance micro-bunches n e = 2.84e22 m -3 λ p = 200 um E r = 1 GVm -1 The Plasma

11. Run ♯ Cell Length (mm) Vacuum Length (mm) Peak Nd @ 2 m (e19 m -3 ) 52.565.54.09 63.057.04.00 73.548.53.90 84.042.03.73 94.537.53.80 105.032.03.64 No vacuum∞0.00.13 Effects of First Cell length 200 200 mm Single cell design. Electrons focused too hard and lost from micro-bunch Two-Stage design results in stable micro-bunches

13. The Diamond light source at RAL uses a 3 GeV electron beam to generate soft x-rays. Beam length: σ z = 26 mm Too long to effectively drive a wakefield! (λ p ~ 100um). A proof of principle experiment has been proposed to micro-bunch the beam using a laser-driven wakefield. The beam can then drive a PWA to: Create a higher energy electron beam Create a poor mans FEL using betatron oscillations within the wake E = 3 GeV ε = 140 nm rad σ z = 26 mm Q = 2 nC Diamond Booster Beam The Diamond Light Source

14. Linac Pictures by Michael Bloom, Imperial College. 90 KeV

15. Booster Pictures by Michael Bloom, Imperial College. 158m circumference

16. The Diamond Experiment Serveral slides of tour of Diamond! Transfer Line Pictures by Michael Bloom, Imperial College.

17. Diamond Booster Param E = 300 MeV ε p = 0 σ z = 0.6 cm σ r = √2 / k p Q = 2 nC Electron beam 1) The long beam given transverse momentum by high amplitude wakefield. 2) Micro-bunches form as half e - defocused, other half focused. 3) At the moment the beam has achieved micro-bunching*, pass into the second plasma cell. The ‘Drift Space’ Design n e = 1.11e22 m -3 λ p = 300 um E r = 1 GVm -1 The Plasma

19. AB

22. Acknowledgements Professor Matthew Wing University College London, London, UK Professor Peter Norreys University of Oxford, Oxfordshire, UK Central Laser Facility, Rutherford Appleton Laboratory, UK Professor Robert Bingham University of Strathclyde, Glasgow, UK Central Laser Facility, Rutherford Appleton Laboratory, UK Doctor Raoul Trines Central Laser Facility, Rutherford Appleton Laboratory, UK Computing resources provided by STFC’s e-Science facility, SCARF and DiRAC.

23. Many existing particle beam facilities Can treat these beams and make them suitable to drive PWA Two-stage drift-space design achieves this over short distances PWA can generate higher energy electrons and in turn generate harder X- rays form existing infrastructure PWA can generate X-rays directly from micro-bunch oscillations Ion motion can be a problem! Thank you for listening Concluding