AAC 2010 Working Group 1 Laser plasma accelerators

Transcription

1 AM PM I PM II AAC 2010 Working Group 1 Laser plasma accelerators Sessions at a glance (Joint in Parens): Tuesday Wednesday Thursday Friday Beam properties Malka, Kaluza, Li Ionization/injection McGuffey, Pak, Kotaki Laser guiding & structure Cros, Hooker, Gonsalves, Krishnan High power & app. s Mangles, Veisz, Karsch Laser/plasma shaping Hosokai, Schramm, Layer Laser & wake diagn./shape Kaganovich, Dong, Palastro Injection (2) Lu, Chen, Kalmykov, Shvets (Khudik) Radiation (4,5) Kneip, Grüner, Jaroszynski, Osterhoff, Martins/Silva Staging & exp. modeling (2) Bourgeois, Geddes, Ting, Wang, Cormier Michel Transport, staging, tech. (4) Weingartner, Nakamura, Sokollik, Pollock Capillaries, radiation, inject. Jaroszynski, Hidding Leads: Cameron Geddes (cgrgeddes@lbl.gov), Chris Clayton, Wei Lu, Alec Thomas Topic groups/summary outline Facilities & high power experiments Guiding and structure control Staging Radiation generation & beam control Beam properties & diagnostics Injection

2 AAC 2010 Working Group 1 Laser plasma accelerators 6/22/2010 WG1 High Power Laser Experiments 2

3 High Power Laser Plasma Experiments Ulrich Schramm FZD Status of the FZD lab combining 150 TW laser pulses with the sc electron linac ELBE ELBE SRF e linac (nc / ps 13 MHz) status (user facility) shielde d combin ed exp. areas upgrade (2011) Combining high power laser with electron linac (ELBE) Thomson scattering experiments Tilt phase fronts to increase Thomson scattering yield Calibration of Lanex and image plates SRF photo gun Ti:Sa L PW DPSSL 6/22/2010 WG1 High Power Laser Experiments 3

4 High Power Laser Plasma Experiments Stefan Karsch LMU, MPQ The CALA project and recent progress in laserdriven electron acceleration at MPQ CALA facility with synchronized laser and beam sources Capillary discharge development Optimized target stable monoenergetic beam X Wang UT Multi GeV electron acceleration using Texas Petawatt laser Simulations show TPW laser is ideal for multi GeV electron generation Inexpensive GeV e energy measurement using calorimeter FDH diagnostic for reconstruction of bubble at small angle streak camera 6/22/2010 WG1 High Power Laser Experiments 4

5 High Power Laser Plasma Experiments Laszlo Veisz MPQ Progress in laser wakefield acceleration with few cycle lasers Self injection Controlled injection Low dark current spectra Sharp density transition improved trapping Normalized RMS emittance measurement scales as 1/γ Generation of few fs pulses Electron 10Energy (MeV) Electron 10 Energy (MeV) Stuart Mangles IC Electron acceleration and x ray generation at IC Pulse compression Off axis electron injection controls betatron coma Energy density threshold for electron injection Power not most useful parameter for characterizing LWFA 6/22/2010 WG1 High Power Laser Experiments 5

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7 Guiding and structure control capillaries Simon Hooker Oxford Generation of electron beams in low density plasma channels Q vs timing Threshold iris/none Capillary Astra Gemini 500 MeV e beams more sensitive to caplaser delay at low n e 80 mbar required guiding 200mbar regardless Use of aperture to clean up spot reduced E thresh,trap ~2x Optical spectra show blueshift w/trapping, raman Nicolas Bourgeois Oxford Plasma channel diagnostic based on laser centroid oscillations Guiding w/ & w/o channel Relativistic shift in Raman Simulated propagation in channels & aperture effect Channel allows guiding at lower n e than self guide alone Spot size effect small Relativistic shift of Raman

8 Guiding and structure control capillaries Tony Gonsalves LBNL Plasma channel diagnostic based on laser centroid oscillations Time scan determines r m Offset scan channel form Spot transverse oscillation provides precise diagnostic of channel depth and shape Scan timing, offset Guide parabolic possible small 4th order Depth matches scalings Brigitte Cros LPGP CNRS Control of laser wakefield amplitude in capillary tubes Modes vs offset Guiding results Calculation need laser pointing < 5mr offset < 0.3R cap Lund Stabize via mechanical, inhibit unstble laser cycle, piezo mirror, DM Guiding at a ~ 0.26, 120mJ Wake amplitude from laser spectral modification, infer 1 7 GV/m

9 Guiding and structure control general Brian Layer UMD Acceleration of Electrons in Modulated Plasma Channels with Radially Polarized Laser Pulses Modulated laser (1) Modulate jet (2) Direct laser acceleration modulate channel to match w/radially polarized laser Channel type1: axicon focused laser modulated by ring grating modulates channel Channel type 2: uniform laser, cluster jet modulated by wires density Tomonao Hosokai Osaka Electron energy boosting with transient micro optics Prepulse vs Bfield Stabilized beam Guide fs few Generate 1d radial like pulse and fields using split pelicle Preplasma shaped by applied magnetic field Forms lens extends laser propagation Increases energy and stability Asymmetric slit jet for density tailoring

10 Guiding and structure control general Mahadevan Krishnan AASC Control of laser wakefield amplitude in capillary tubes Valve Open/close time Fast gas valve using flyer plate opening 70µs open, few hundred close Scalable to 10 s µs Cooling for rep rate, shaping

11 Guiding and structure control capillaries Antonio Ting NRL Plasma Density Tapering for LWFA of Electrons and Protons Beat phase vel. vs spot ratio Plasma density up taper compensates wake v < c Bucket jumping extends range Protons acceleration with: Down taper 20 GeV in 10 cm Near n crit wakes Beat wave w/ different spot size and quasi phase match 2MeV / period Cameron Geddes LBNL Laser Plasma Wakefield Acceleration w/high Order Laser Modes * E. Cormier Michel et al, submitted HOM Gaussian Small matched bunch radius limits chrage for low beams Decrease focusing fields by tailoring transverse laser mode in quasilinear regime Propagate to depletion in channel Increase matched radius & Qcan adjust wake phase for BL

12 Discussion Discharge capillaries 500 MeV beams from Astra Gemini capillary experiments Spot quality critical to injection threshold Guide allows propagation, injection at lower density Precise diagnostics of profile with laser centroid oscillation Glass capillaries guiding characteristics w/pointing, wake via GV/m New jets developed using flyer plate method for high speed pulses Direct acceleration guides formed by modulated beams, jets. Suitable laser via pelicle cut in beam Stage design Taper for electron or proton acceleration Proton acceleration via taper or beat wave Emittance matching controlled in quasilinear regime using laser mode for efficiency

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14 Thomas Sokillik LBNL Tape drive based Plasma Mirror Staging R vs I Need to minimize coupling distance between stages to maximze gradient in collider Plasma mirrors cm scale Tested tape mirror 80% R Profiled material roughness Bradley Pollock UCSD/ LLNL Laser Wakefield Acceleration in a Two Stage Gas Cell Trapping threshold 2 stage gas cell Calisto experiments 200TW, ~30% in central spot Accel to 700 MeV in cm jets, self trap threshold measured 2 stage cell (short ionization mix region) built, sims 1.5GeV low de

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16 Radiation from Laser Plasma Accelerators Stefan Kneip UM Laser Plasma Accelerator and Wiggler Florian Gruener LMU, MPQ Laser driven soft X ray Undulator Source x rays measured from betatron oscillations in a LWFA Beam is well collimated and stable Source size is ~µm Peak spectral brightness comparable to 3 rd Gen Synchrotrons Laser driven undulator source First application experiment Lab scale XFEL High stability of beams required 6/22/2010 WG1 Radiation and Staging 16

17 Radiation from Laser Plasma Accelerators Dino Jarozynski Strathclyde High brightness electron beams from a Laser Plasma Wakefield Accelerator No slides available Laser wakefield acceleration to inject into undulator Imaging spectrometer Measurements of electron beam emittance using pepperpot technique MeV betatron radiation Jens Osterhoff LBNL Controlled transport of ultra relativistic e beams from LPAs by mini quad magnets Beam transport using quadrupole magnets Decrease energy error from alignment Increase yield of undulator Increased pointing stability of electron beam 6/22/2010 WG1 Radiation and Staging 17

18 Radiation from Laser Plasma Accelerators Raphael Weingartner LMU Imaging laser wakefield accelerated electrons using magnetic quadrupole lenses Joanna Martins (Luis O Silva) IST Simulation of radiation from plasma based accelerators No slides available Beam transport using quadrupole magnets Excellent control over electron bunch while maintaining bunch length and emittance Control over steering Energy spread of < 2% rms measured with imaging spectrometer Post processing of particle trajectories from OSIRIS virtual detector photon flux via spectral integrals Injection, acceleration effect on spectrum Bright 2 MeV photon source with 12 GeV accelerator 6/22/2010 WG1 Radiation and Staging 18

19 Radiation from Laser Plasma Accelerators Bernhard Hidding Space Radiation Studies A Novel Killer Application for Laser Plasma Accelerators? Using LPAs to investigate effects of space radiation Comparably cost effective additional testing beam time May increase testing realismreliability/safety Proliferation aspects (replace radioactive sources) Exponential electron and proton spectrum 6/22/2010 WG1 Radiation and Staging 19

20 Radiation from Laser Plasma Accelerators DISCUSSION Radiation generation using plasma based acceleration very favorable E Beam properties potentially excellent small source size, reasonable emittance, ultrashort duration Two approaches 1. Generate low emittance bunches and inject into external undulator Low emittance may motivate controlled injection Conventional/engineering 2. Generate radiation from betatron oscillations in wake Ultra Compact Spontaneous Applications FEL radiation vs Synchrotron Beam transport and stability Coherence properties Physics X rays as a diagnostic of electron dynamics Radiation reaction force effects Ultrashort duration for pumpprobe experiments 6/22/2010 WG1 Radiation and Staging 20

21 AAC 2010 Working Group 1 Laser plasma accelerators 6/22/2010 WG1 High Power Laser Experiments 21

22 Charge is important Victor Malka (LOA) A few fs electron bunch produced with LPA image here Correlation! Kei Nakamura (LBNL) Electron Beam Charge Diagnostics for LPA s image here Two colliding laser beams allow for control of energy and phase space volume: > Beam loading Tunable: MeV Tunable: 1 to 10 s pc de/e down to 1 % Good beam quality CTR shows 1.5 fs RMS Peak current : 4kA Some controversy regarding: ICT, image plate, Lanex, activation > Cross calibration needed. Issues Energy Charge Q/mm 2 (saturation) Pulse length Good agreement so far! BPM s may be accurate

23 Wake structure (1 of 2) Malte Kaluza (IOQ Jena) Optical Diagnostics for LPA Hosing Faraday High resolution (< 3 μm) side scatter images Evidence of self focusing long wavelength hosing wavelength increases with decreasing plasma density > Pulse front tilt Asymmetric ponderomotive force Polarograms (Faraday rotation) see bubble displacement current + electrons Zhengyn Li (UT Austin) Frequency Domain Streak Camera:Imaging EVOLVING Wakes image here New twist on FDH Conventional X ray style CT projection static object, moving probe In frame of FDSC probe Static probe, moving object Tested with Kerr medium Ready for wakefield!

24 Electron Energy (MeV) Wake structure (2 of 2) Dmitri Kaganovich (NRL) Measurements of the Plasma Bubble Dynamics and e Trapping in a LWFA a off-axis electrons image here Plasma Density (10 19 cm -3 ) b on-axis electrons measurement threshold Peng Dong (UT Austin) Formation of optical bullets in LWFA bubbles image here Electron Charge (nc) Discovery through computation Explained off axis electrons Electro optic shock Conical 2 0 light Experimentally confirmed correlated with electrons > New diagnostic Ring angle, thickness correlated with experimental parameters New twist on FDH Trapping and modification of probe beam by plasma bubble AM reconstruction of pulse Potential for optical compressor Structure change with density, traping

25 Instability? John Palastro (U Md) FRS of Intense Pulses in Modulated Plasmas image here Acceleration time is limited by pulse length > Raman instability has time to grow How much? modulations reduce low mode growth but enhance high mode growth Conical 2 0 light A fortuitous effect for realistic leaky channels

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27 Ionization Injection (experiments) C. McGuffey et al. (U. of Michigan) Effects of ionization and laser/plasma interaction Monoenergetic beam 2010 Different mixed gases Increased charge Monoenergetic beam (a few hundreds MeV) High power (100TW) operation McGuffey, et al. Phys. Rev. Lett., (2010) A. Pak et al., (UCLA) Injection of Tunnel Ionized Electrons into LWFA A. Pak, et. al. Phys. Rev. Lett., (2010) Mixed gas (He +N) ~100MeV beam Reduced injection threshold on a0 Agreement between experiment and simulations Simple model on threshold

28 Ionization Injection (experiments) B. Pollock et al., (LLNL) 1.5GeV beam from Ionization injection at 120TW Energy record up to 1.5GeV Continuous spectral 1.3cm gas cell He+CO2 mixed gas Clayton et al., PRL submitted (UCLA) K. Nakamura et al., (LBNL) Stable injector using Ionization trapping image here 3e18/cc jet no injection without gas mix Mixed gas 12MeV stable de~6mev (FWHM) 25pC

29 Injection (experiments) H. Kotaki JAEA Stable electron bunch generation with a 3.2TW Ti:sapphire laser for injectors... Injection and propagation stabilized in Ar/N2 vs He 130 MeV beams at 3TW & also sub MeV beams Steer beam w/jet position Polarization dependent oscillation used to infer bunch length ~ 4 fs Colliding pulse injection Talk Victor Malka see beam properties section Poster, Plateau

30 Injection (theory and simulation) W. Lu et al. (UCLA) Self and controlled Injection of LWFA and PWFA 2 0 v p x0 0 1 p 2 General trapping condition for non evolving wakes Physical picture of injection (two step process) Simulation verification of the physical picture by utilizing nonevolving beam drivers discssions on the effects of driver shape, plasma channels W. Lu et al., PhD Dissertation (2006) M. Chen et al., (LBNL) Ionization induced electron injection in LWFA PIC & theoretical treatment Injection@low wake amplitude Short mixed gas controls charge, improves E Laser skew controls E Control of P perp w/low a 0

31 Injection (theory and simulation) S. Kalmykov et al., (U. of Nebraska, Lincoln) Electron self-injection into an evolving plasma bubble Evolving bubble helps electron injection laser evolution induced bubble expansion can shut off injection, may lead to monoenergetic beam Quasi static code Wake with test particles can give reasonable agreement with full PIC under certain conditions S. Kalmykov et al., PRL (2009) G. Shvets et al., (U. of Austin) Electron Self Inject. and Accel. into an Evolving Plasma "Bubble" 2 H d H Hmc / d 1 v v 0 x Expanding bubble changes the Hamitonian and trapping conditon Bubble expansion followed by stabilization for low E

32 Injection (theory and simulation) E. Cormier-Michel et al., (LBNL) Predictive design of colliding pulse injected LWFA Colliding pulse injection allows high quality beam Simulation scan to predict experimental results Optimum density for trapped charge Scaled parameters show scaling law