SLAC Accelerator Research Program Tor Raubenheimer SLUO Meeting, July 17, 2009

SLUO Meeting July 16, 2009 Page 2 / 25 What is Accelerator Research? Accelerators are throughout medicine, science, & industry –Accelerator research is basis for future development Analogous to laser research –Motivated by the applications as well as the science The R&D is broad both in topic and timescale –Materials surface physics, magnet design, Hamiltonian dynamics –Direct accelerator improvements to concept exploration with application more than 20-years in the future Accelerator R&D is usually directed towards applications –Results can have broad impact, e.g. L-band & C-band linear collider R&D provided the basis for DESY and Spring-8 XFEL’s –High Energy Physics is one of the greatest challenges

SLUO Meeting July 16, 2009 Page 3 / 25 Key Challenges in Accelerator Physics Beam brightness and control  peak luminosity and radiation source brightness –Brightness is flux divided by 6-D phase space volume (emittance) which should be conserved after beam creation Beam energy  energy reach or radiation wavelength –Critical problem for HEP requiring new cost-effective concepts –Novel concepts will enable new applications elsewhere as well Beam power  average luminosity or brightness –Power (average current times energy) is frequently measured in megawatts and has both technical and physical limitations SLAC Accelerator Research group has effort in all areas

SLUO Meeting July 16, 2009 Page 4 / 25 SLAC Experimental Facilities LCLS Undulator 2 End Station Test Beam SLAC has extensive experimental facilities to enable accelerator R&D –SLAC Linac and infrastructure  FACET, Injector Test Facility (ITF), ESTB, PEP-X, and SLC Arcs –NLC Test Accelerator –Accelerator Structure Test Area (ASTA) –GTF (SSRL), GTF (ILC), CTF, … –End Station A, End Station B, Klystron Test Lab Important to have different facilities with different energy scales.

SLUO Meeting July 16, 2009 Page 5 / 25 SLAC Accelerator Research Program Broad program –Working on LCLS, SPEAR-III, and LHC –Efforts on upgrades for LCLS and LHC; Design efforts on ILC, CLIC, Super-B, Project-X, PEP-X, and test facilities –R&D towards higher brightness, higher gradient, and higher power Program takes advantage of SLAC facilities, expertise and core competencies –High power RF; beam theory and computing; Stanford University Strong programs at international facilities –CERN on CLIC / CTF3 and LHC –KEK on ATF / ATF2 –INFN on Super-B –Smaller collaborations with IHEP, DESY, …

SLUO Meeting July 16, 2009 Page 6 / 25 LHC R&D (Subject of later talks) Novel collimators (building prototype LHC collimator) –Spin off of Linear Collider R&D program –R&D uses Klystron Department and beam theory expertise –Engagement has led to R&D on new concepts such as crystal collimation which may have impact for LC and future rad. sources Electron Cloud and E-cloud Feedback –Application of R&D on e+/e- colliders Low level RF –Application of concepts and technologies developed for PEP-II Crab cavity design –Synergistic with LC; utilizes beam theory expertise; broad use Program keeps engagement in premier HEP accelerator

SLUO Meeting July 16, 2009 Page 7 / 25 SLAC ILC Program Most developed near-term option for a TeV-scale collider Focus on R&D synergistic with rest of the program 1.3 GHz RF power source R&D –Modulators –Klystrons –RF distribution and couplers Electron source R&D –Photocathode development Beam delivery system R&D –FFS optics and tuning design –Collimation and beam dump design –MDI design with FD and crab cavity –ATF / ATF2 Test facility Damping ring & e-cloud R&D Synergistic with Project-X R&D, future LC R&D, and CW light source R&D Synergistic with future LC R&D and with Super B-factory & PEP-X R&D

SLUO Meeting July 16, 2009 Page 8 / 25 Marx Modulator and 10MW Klystron Marx Modulator installed in ESB and powering Toshiba 10 MW klystron

SLUO Meeting July 16, 2009 Page 9 / 25 ATF2 Final Focus ATF2 is aiming for 35 nm spots SLAC provided magnets, movers, power supplies, BPMs, diagnostics Has led the effort building tuning tools for commissioning ATF2 commissioning in Dec 2008

SLUO Meeting July 16, 2009 Page 10 / 25 RF Distribution and Couplers Coupler class-10 clean room Coupler processing results ILC Rf distribution system

SLUO Meeting July 16, 2009 Page 11 / 25 Accelerator Science Program Beam theory and Computing –Echo-enhanced harmonic gain; EM design of LHC crab cavity High gradient X-band program –RF testing of CLIC PETS structure in ASTA –Tested two high gradient structures in NLCTA –Study of materials for high gradient performance Direct laser acceleration –Reconfiguring experiment for the PBG fiber experiment Plasma wakefield effort is focused on the FACET project

SLUO Meeting July 16, 2009 Page 12 / 25 Echo-Enhanced Harmonic Generation Novel approach to harmonic generation that potentially seeds harmonics as high as a few 100 –Seeding increases the temporal coherence and spectral brightness and shortens the required undulator length Planning experiment to verify EEHG at NLC Test Accelerator this year Evolution of the longi- tudinal phase space (one laser period is shown): 1. Energy modulation after first modulator 2. Tilted beamlets in the phase space after the first chicane 3. Energy modulation after the second modulator 4. Phase space after the second chicane

SLUO Meeting July 16, 2009 Page 13 / 25 High Gradient R&D P5 noted that a future lepton collider will be a necessary complement to the LHC –The science case remains strong SLAC has been developing LC concepts for 30 years Many options for the next-generation collider with different levels of risk and different costs –ILC: most developed, lowest risk but high cost –High gradient klystron: medium risk with significant cost savings –Drive-beam microwave: higher risk with probably greater savings –Dielectric or Plasma acceleration: much higher risk but with potential for much lower costs R&D programs on these different options have broad applicability across Office of Science

SLUO Meeting July 16, 2009 Page 14 / 25 High Gradient Microwave Acceleration Extensive R&D on breakdown limitations in microwave structures –US High Gradient Collaboration –CERN and Japan In the last few years: –X-band gradients have gone from ~50 MV/m loaded to demonstrations of ~150 MV/m loaded with ~100 MV/m expected –Greatly improved understanding of breakdown and limits

SLUO Meeting July 16, 2009 Page 15 / 25 NLC Test Accelerator: RF Testing 3 x RF stations –2 x pulse compressors (240ns - 300MW max), driven each by 2 x 50MW X-band klystrons –1 x pulse compressors (400ns – 300MW /200ns – 500MW variable), driven by 2 x 50MW X-band klystrons. 1 x Injector: 65MeV, ~0.3 nC / bunch In the accelerator housing: –2 x 2.5m slots for structures Shielding Enclosure: suitable up to 1 GeV For operation: –Can run 24/7 using automated controls (Gain = 3.1)

SLUO Meeting July 16, 2009 Page 16 / 25 July 8, 2008Page 16 ASTA Test Facility From Two 50 MW Klystrons Variable iris Variable Delay line length through variable mode converter Gate Valves Two experimental stations inside the enclosure, one with compressed pulse and the other without the benefit of the pulse compressor. Designed for economical testing of TW, SW accelerator structures, and waveguides. Add an electron gun to test gradients next year Versatile structure for future applications (beyond high gradient work)

SLUO Meeting July 16, 2009 Page 17 / 25 High Gradient Acceleration with Lasers Laser capability improving rapidly –Billion $ industrial development effort Two acceleration approaches using lasers: –Laser wakefield (plasma) acceleration, i.e BELLA(10 GV/m) –Direct laser (dielectric) acceleration, i.e. E-163 (1 GV/m) Real challenges for both approaches Very different laser requirements –Both require high average power  must generate beam power Laser-wakefield acceleration requires high peak laser power –Lasers are most efficient and cost effective near CW operation CW operation is best use of expensive amplification medium  SLAC is pursuing direct laser acceleration with ~10,000 times lower peak power requirements  more favorable cost scaling

SLUO Meeting July 16, 2009 Page 18 / 25 The E-163 Facility at the NLCTA (Commissioned in March 2007) RF PhotoInjector Ti:Sapphire Laser System Next Linear Collider Test Accelerator Cl. 10,000 Clean Room Counting Room (b. 225) Optical Microbuncher Gun Spectrometer ESBESB Next Linear Collider Test Accelerator E-163 The E163 program has advanced rapidly due to three factors: A decade of experience conducting this type of experiment at LEAP Extensive NLCTA infrastructure required modest extension to make a functioning facility Experienced help from the Test Facilities staff at every step Experimental Hall

SLUO Meeting July 16, 2009 Page 19 / 25 Staged Laser Acceleration Experiment Total Mach-Zender Interferometer path length: ~19 feet = 7.2x10 6 !! All-passive stabilization used (high-mass, high- rigidity mounts, protection from air currents) Energy Spectrometer Buncher Accelerator 3 feet e

SLUO Meeting July 16, 2009 Page 20 / 25 New SLAC Experimental Facility: FACET New FACET facility will provide high quality 25 GeV e+ & e- beams for studies of plasma wakefield acceleration –Plasma wakefield acceleration could reduce cost/GeV significantly for linear colliders and could provide an easy upgrade for FEL facilities –FACET will also be used to develop beam-driven dielectric acceleration and plasma focusing concepts as well as other beam physics studies Beams of e+ / e- at 25 GeV with 20kA and 10x10 um spot sizes –Unique facility is only possible because of SLAC linac FACET timescale 2010 – 2017 Scheduling CD1 Review in June LCLS Undulator 2 End Station Test Beam

SLUO Meeting July 16, 2009 Page 21 / 25 Promise of Plasma Acceleration (Beam-driven or Laser-driven) 50 GV/m in FFTB experiments –Potential use for linear colliders and radiation sources Simulation of 25 GeV PWFA stage Drive bunch Witness bunch

SLUO Meeting July 16, 2009 Page 22 / 25 Broad Research Capability Unique science opportunities in many fields: –Plasma beam source for LC concepts or radiation source –Plasma lens for compact focusing –Bent crystal for beam collimation or photon source –e+ and e- acceleration study essential for LWFA & PWFA –Dielectric wakefield acceleration –Energy-doubling for existing facilities such as FEL’s –Generation of THz radiation for materials studies Short bunches and their Tera-Hz radiation open new possibilities to study ultrafast magnetization switching

SLUO Meeting July 16, 2009 Page 23 / 25 FACET Program Development FACET is aimed at R&D on Plasma Wakefield Acceleration however unique beams will be used for broader research –Originally proposed a 3:1 ratio between PWFA and other programs Present PWFA collaboration (UCLA, USC, SLAC) is developing new formal collaboration structure –Will grow collaborations to support full PWFA R&D program Two workshops planned on Advanced Accelerator / PWFA –ICFA Mini-Workshop on Novel Concepts for Linear Accelerators and Colliders, July 8-10, 2009 –Workshop on PWFA and FACET Research Opportunities, Feb 2010 Creating external advisory committee to review the SLAC Accelerator Research program as well as FACET

SLUO Meeting July 16, 2009 Page 24 / 25

SLUO Meeting July 16, 2009 Page 25 / 25 Summary of SLAC Accelerator Research Excellent research programs in Accelerator Science: –High gradient acceleration: microwave structures, direct laser acceleration, plasma wakefield acceleration –High brightness sources; Beam physics and computing Strong programs on existing and next generation accelerators at SLAC and world-wide Laboratory has unique experimental facilities –End Stations A and B, SLAC Linac, ASTA, Klystron Test stations, NLC Test Accelerator with FACET and ITF in the future Excellent technical support and fabrication capabilities and strong ties to Stanford University SLAC accelerator research is key to the future of the laboratory and to the international accelerator program

SLUO Meeting July 16, 2009 Page 26 / 25 Backup END OF TALK

SLUO Meeting July 16, 2009 Page 27 / 25 Potential for Near-term Development ASTA  photo cathode test facility as well as rf test facility –Supports high brightness source development and LCLS upgrades NLCTA  support quick Acc Science experiments as well as rf testing and DLA programs –Not planning to convert NLCTA into full fledged user facility SLAC Linac  FACET and Injector Test Facility (ITF) –FACET will support plasma acceleration and intense beam R&D –ITF will be able to support a broad program of beam manipulation LCLS  End Station Test Beams and LCLS Undulator #2 –User facility for HEP and BES using End Station A

SLUO Meeting July 16, 2009 Page 28 / 25 SLAC Linac Sectors 0-20 Plans for the SLAC Linac include FACET, ITF, and LCLS Undulator 3 –SLAC linac is a unique resource –Cost to maintain the linac in a warm state: ~7 M$ / year –FACET and ITF operations would invest another 6~7 M$ / year –Critical to maintain linac in operation state to ensure future capability

SLUO Meeting July 16, 2009 Page 29 / 25 Injector Test Facility Injector Test Facility (ITF) –Use SLAC linac to characterize the beam emittance –Develop cathodes and rf gun technology –Will be placed to serve as the injector for LCLS upgrades –Dramatically reduces risks on LCLS upgrades to harder x-rays

SLUO Meeting July 16, 2009 Page 30 / 25 SLAC Research Yard ESA ESB LCLS BSY NLCTA

SLUO Meeting July 16, 2009 Page 31 / 25 End Station A – ESTB & LCLS U2 End Station A is proposed to house Undulator 2 –Undulator 2 and parasitic HEP test beam to be developed Optimization of Undulator 2: seeding options, ESASE, … –Need to develop pulse sharing mechanism with Undulator 1 Operate with multibunch trains Alternate pulses Beam Switch Yard Secondary Target and Undulator End Station A: Undulator 2

SLUO Meeting July 16, 2009 Page 32 / 25 End Station B

SLUO Meeting July 16, 2009 Page 33 / 25 Direct Laser Acceleration (E-163) Experiment Layout (telecom ) 2R (defect) (µm) a (pitch) (µm) lattice dia. (µm) cladding dia. (µm) / commercial fiber candidates: 10 µm HC-1060 Fiber simulation of accelerating mode Permanent Magnet Quadrupoles fiber aperture  * = 0.5 mm PMQB’(T/m)Bint(T)Leff(mm) Simulated Field Strengths (RADIA) Completed April wedge Halbach geometry Material: NdFeB Remote actuation: - intra-quad spacings - z position of assembly - insert/remove from beam path String encoder position read-back In-vacuum assembly SEM scan of fiber

SLUO Meeting July 16, 2009 Page 34 / 25 EEHG Demonstration at NLCTA Use 120 MeV beam from rf gun with 20 pC and  < 8 mm-mrad