Study of Plasma-Based Acceleration for High Energy Physics and Other Applications Zur Erlangung des akademischen Grades eines DOKTORS DER NATURWISSENSCHAFTEN von der Fakult¨at fur¨ Physik des Karlsruher Institutes fur¨ Technologie (KIT) genehmigte DISSERTATION von Dipl.-Phys. Steffen Hillenbrand aus Stuttgart Tag der mundlichen¨ Prufung:¨ 6. Dezember 2013 Referent: Prof. Dr. Anke-Susanne Muller¨ Korreferent: Prof. Dr. Gunter¨ Quast Contents 1 Introduction 1 2 Theory of Plasma Based Accelerators 5 2.1 Introduction to Plasma Based Acceleration . .5 2.1.1 General Principle . .5 2.1.2 Linear and Non-Linear Regime . .6 2.1.3 Overview of Different Driver Technologies . .6 2.2 Basic Accelerator Physics . .8 2.2.1 Emittance . .8 2.2.2 Beta-Function . .8 Phase Advance . .9 2.2.3 Dispersion . .9 2.3 Introduction to Plasma Properties . .9 2.3.1 Plasma (Langmuir) Frequency . 10 2.3.2 Plasma Wavelength, Plasma Skin Depth . 10 2.3.3 Wave Breaking Field . 11 2.4 Introduction to High Power Lasers . 11 2.4.1 Optical Intensity . 11 2.4.2 Laser Strength Parameter . 12 2.4.3 Polarization . 12 2.4.4 Laser Wavelength, Chirped Pulse Amplification . 13 2.4.5 Rayleigh Length . 13 2.4.6 Phase and Group Velocity . 14 2.5 Laser-Driven Acceleration in the Linear Regime . 14 2.5.1 Introduction . 14 2.5.2 Plasma-Based Laser-Driven Accelerator Concepts . 15 Plasma Beat Wave Accelerator - PBWA . 15 Resonant Laser Plasma Accelerator - RLPA . 15 Self-modulated Laser Wakefield Accelerator - SMLWFA . 16 Laser Wakefield Acceleration - LWFA . 17 2.5.3 Ponderomotive Force . 17 2.5.4 Diffraction, Optical Guiding . 17 2.5.5 Dephasing . 19 2.5.6 Depletion . 19 2.6 Electron-Driven Acceleration in the Linear Regime . 19 iv Contents 2.6.1 Acceleration Gradient . 20 2.6.2 Transformer Ratio . 20 2.6.3 Dephasing . 20 2.6.4 Diffraction, Head Erosion . 20 2.7 Proton-Driven Acceleration . 21 2.7.1 Positively Charged Driver . 21 2.7.2 Self Modulated Driver . 21 2.7.3 Dephasing . 22 Short Driver . 22 SelfModulatedDriver .......................... 22 2.8 Acceleration in the Nonlinear Regime . 23 2.8.1 Beam Matching, Electron Driver . 23 2.8.2 Hosing . 24 2.8.3 Scaling with Plasma Density . 24 Beam Scattering . 25 Ion Motion . 26 Beam Head Erosion . 26 2.9 Beam Loading . 27 2.9.1 Beam Loading in the Linear Regime . 27 Tailoring of Bunch shape . 28 Gaussian Bunches . 30 Transverse Beam Loading Consideration . 30 3 Status of Experimental Studies 33 3.1 Laser Wakefield Acceleration . 33 3.1.1 Achieved Electron Beam Parameters . 33 Bunch Shaping . 34 3.1.2 Status of High Power Laser Systems . 37 Pulse Energy and Repetition Rate . 37 Wall-plug Efficiency . 38 3.1.3 Conversion Efficiencies . 40 3.2 Participation to LWFA Experiment . 41 3.2.1 Beam Position Monitor Measurements . 41 Experimental Setup . 41 Results .................................. 44 Discussion . 44 3.3 Plasma Wakefield Acceleration . 45 4 Study of High Energy Lepton Colliders 47 4.1 Constraints . 48 4.1.1 Energy and Luminosity . 48 4.1.2 Beam-Beam Interaction . 49 Beam disruption . 49 Beamstrahlung . 49 Contents v Coherent Beamstrahlung Pair Production . 50 Trident Cascade . 51 4.2 Laser-Driven Linear Collider . 52 Evaluation ................................ 54 4.3 Electron-Driven Linear Collider . 58 4.3.1 Staged Approach . 58 4.3.2 Afterburner . 58 4.4 Proton-Driven Linear Collider . 59 Proton Based ILC Upgrade . 59 Electron-Proton Collider . 59 Dedicated Proton Driver . 60 4.5 Photon-Photon Collider . 60 4.6 Muon Collider . 61 4.7 A 130 GeV Higgs Factory . 62 4.7.1 Motivation . 62 4.7.2 Protons as Drive Beam . 62 4.7.3 LWFA Electron-Positron Collider, Classical Beamstrahlung Regime . 62 Interim Conclusion . 65 4.7.4 LWFA Electron-Positron Collider, Quantum Beamstrahlung Regime . 65 Discussion . 65 4.7.5 Photon-Photon Collider, PWFA in the Bubble Regime . 66 Discussion . 69 4.7.6 Evaluation . 71 5 Possible Mid-Term Applications 73 5.1 Free Electron Laser . 73 5.1.1 Choice of Driver Technology . 74 5.1.2 Possible LWFA Parameters . 74 5.1.3 Discussion . 77 5.2 LWFA as Injector for ANKA . 78 5.2.1 Transfer Line to ANKA . 81 5.2.2 Behaviour in Synchrotron - Longitudinal . 81 5.2.3 Behaviour in Synchrotron - Transversal . 85 5.2.4 Discussion . 87 6 Studies for the AWAKE Experiment at CERN 89 6.1 Experiment Description . 89 6.1.1 CERN Accelerators, Choice of Experimental Area . 89 6.1.2 Proton Beam Parameters . 91 Proton Beam Delivery . 92 6.1.3 Electron Beam Parameters . 92 vi Contents 6.1.4 The Plasma Cell . 92 Plasma Parameters . 93 6.2 Interface from Plasma to Beam Simulations . 94 6.2.1 Proton Bunch Simulations, 10 m Plasma Cell . 94 Default Bunch Charge - SPS-LHC Parameter Set . 94 High Bunch Charge - SPS-Opt Parameter Set . 99 6.2.2 Proton Bunch Simulations, Different Cell Lengths . 101 6.2.3 Electron Bunch Simulations . 101 6.3 Detection of Energy Gain . 103 6.3.1 General Principle . 103 6.3.2 Implementation . 103 6.3.3 Proton Spectrometer without Focussing . 104 6.3.4 Proton Spectrometer with Focusing . ..