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The Accelerator Test Facility and Optical Stochastic Cooling R&D

The Accelerator Test Facility and Optical Stochastic Cooling R&D. HEPAP AARD Sub panel Vitaly Yakimenko Brookhaven National Laboratory February 15, 2006. The ATF is a proposal-driven, advisory committee reviewed USER FACILITY for long-term R&D into the Physics of Beams.

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The Accelerator Test Facility and Optical Stochastic Cooling R&D

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  1. The Accelerator Test Facility and Optical Stochastic Cooling R&D HEPAP AARD Sub panel Vitaly Yakimenko Brookhaven National Laboratory February 15, 2006

  2. The ATF is a proposal-driven, advisory committee reviewed USER FACILITY for long-term R&D into the Physics of Beams. The ATF serves the whole community: National Labs, universities, industry and international collaborations. ATF contributes to Education in Beam Physics. (~2 PhD / year) In-house R&D on photoinjectors, lasers, diagnostics, computer control and more (~3 Phys. Rev. X / year) Support from HEP and BES. The ATF features: High brightness electron gun 75 Mev Linac High power lasers beam-synchronized at the picosec level (TW level CO2 laser) 4 beam lines + controls BNL Accelerator Test Facility - ATF

  3. Main facility results/directions: Facility (concept, developments and name are copied) 24 PhD students graduated • High brightness injectors: • Electron beam diagnostics • Development of a picoseconds Terawatt CO2 laser • Generation of the short bunches on all scales • Experimental demonstration of various advanced acceleration techniques • Free Electron Laser experiments

  4. Why we need better emittance To match FEL or accelerating optical and electron beams; or to transport through small (high frequency) accelerating channel Gun IV Mg cathode Mg cathode First 1.6 cell gun 5 mm Thomson X-ray source HGHG SASE @1mm STELLA 2 mm Dielectric WFA IFEL ICA Micro bunching 1 mm VISA Smith Purcell experiment Plasma WFA 0.5 mm 1995 1998 2001 2004 Design of the 1.6 cell gun is adopted in more then a dozen facilities

  5. ATF Terawatt CO2 Laser Story (past and present) Ion and Proton source 3 TW Seeded LWFA Resonant PWA LACARA PASER 300 GW Nonlinear Thomson scattering EUV source HGHG STELLA 30 GW Thomson X-ray source Inverse Cherenkov accelerator IFEL accelerator 3 GW 1995 2000 2005 2010

  6. FACILITY CO2 LASER LINAC DEVICES Plasma Wiggler 1st generation experiments wake field laser channel micro- bunching STELLA resonant wakefield seeded LWFA PASER 2nd generation experiments

  7. Near-term plan (2-3 year scale) • Multi-bunch plasma wake field acceleration experiments to demonstrate a high transformer ratio and a mono-energetic accelerated e-beam. • Generation of ion, neutron, and proton beams with MeV energies from a foil and gas jet with a multi-Terawatt CO2 laser. • Upgrade of the CO2 laser to the 20TW level and experimental studies of advanced accelerators and radiation sources in a strong-field relativistic regime. • Operation and characterization of a visible SASE FEL in the amplifier regime. • Continued improvement of electron beam brightness utilizing a photoinjector laser upgrade, advances in beam diagnostics and beam compression.

  8. ATF Budget Analysis: FY03/07 ($K) • PROJECT FY03 FY04 FY05 FY06(cur) FY07(proj) • ATF Ops $1,680 $1,800 $1,800 $1800 $1,990 • ATF Equ $200 $200 $200 $200 $220 • ATF (BES) $500 $500 $500 $500 $500 • Totals: $2,380 $2,500 $2,500 $2,500 $2,710 • ATF is supported by • LDRD at different levels from its formation (currently 120K$/year) • HEP DOE from 1991 (directly) • BES DOE from 1991 (indirectly) from 2002 (directly) • ATF continues to be staffed at the critically low level: • Recent reduction in the scientific personnel by 2 has negatively affected facility efficiency. • Increase in staff is needed to improve support of experiments, increase run time and make users programs more efficient.

  9. ATF Org. chart

  10. Time resolved optical spectrum of the plasma emission was measured to characterize plasma #31 density USC & ATF CTR spectrum was measured by S. Banna #30 using UCLA bolometer #26 and THz filters from STI #32 to characterize beam Beam was sent through plasma channel ATF & STI #32 in the first PWF double beam experiment ne [cm-3.] CTR [a.u.] E time delay [ns] Filter cutoff [mm] Story of one short experiment … Beam break up was noticed during beam compression studies by UCLA. Beam before final compression Beam after final compression ~1 ps ~100 fs E E Experiments are very sophisticated and very efficient sharing of the resources between experimental groups is essential

  11. sample length ~10 cm sample length ~50 mm Basic idea of OSC Stochastic Cooling Optical Stochastic Cooling In practice In practice time is amplifier limited • ~ 5 cm => ideal bandwidth limited cooling time t~2.5 hrs. • ~ 12 mm => power limited cooling time t~1 hr with 16 W; bandwidth limited t~11 sec!

  12. 5 main components of OSC • Pair (per ring) of super conductive wigglers • Optical amplifier (Optical Parametric Amplifier (OPA): • Pump source for OPA • Lattice modification • Diagnostics

  13. Optical Parametric Amplifier OPA 3 cm length crystal → intensity gain 3 105 Parametric process is photon interaction in which one high frequency photon is annihilated and two lower frequency photons are created, i.e.: w(pump) =w(signal) +w(idler) where photon energy is conserved. In addition, photon momentum is conserved by the wave vectors: k(pump) =k(signal) +k(idler).

  14. OPA test at ATF • Basic parameters of the crystal • Bandwidth of the amplifier • Phase fidelity

  15. Future development ATF ? • acquire X-band technology (extreme beam compression, diagnostics, testing of X-band devices, high gradient…) • Polarized Positron Source (PPS) with linac and CO2 laser R&D for ILC • upgrade of CO2 system to 300TW level and high field experiments • energy upgrade to 1GeV with energy recirculator (PWFA experiments, PPP)

  16. Electron cooler in RHIC IP12

  17. Number of particles in the ion bunch (as a result of “burn-off”, recombination, cooling, IBS) <L>=7e27 <L>=6e27 Recombination: OFF Recombination: ON Wigglers: OFF <L>=6e27 Average store Luminosity without Cooling 6e26 Integrated luminosity is about the same as without suppression of recombination due to reduction in cooling force Recombination: ON Wigglers: ON

  18. 20 MeV High Current High Brightness R&D ERL : layout in 912

  19. Ampere Class Cryomodule “Single mode cavity”: HOM (R/Q)Q~2*103 Ohms monopoles, ~2*105 Ohms/m dipole modes. BBU threshold current > 2 amperes

  20. SRF Gun – critical element Top cover with facilities feedthru Internal Helium dewar Cathode installation assembly Cathode isolation Valves Cavity assembly HOM Ferrite Magnetic and thermal shielding Beam line isolation valve Insulating Vacuum Port Adjustable supports Power couplers Vacuum vessel

  21. Gain of 50, still increasing W/ field, further investigation underway Gain in Emission mode From Hydrogenated samples

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