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KEK ATF – spring 2004

KEK ATF – spring 2004. Thursday, July 29, 2004. Marc Ross. ATF. For generation&confirmation of LC low emittance e - beam. E=1.28GeV Ne=1x10 10 e - /bunch 1 ~ 20 bunches Rep=1.5Hz X emit=2.5E-6 ( at 0 intensity) Y emit=2.5E-8 ( at 0 intensity). Vertical Emittance development.

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KEK ATF – spring 2004

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  1. KEK ATF – spring 2004 Thursday, July 29, 2004 Marc Ross

  2. ATF For generation&confirmation of LC low emittance e- beam E=1.28GeV Ne=1x1010 e-/bunch 1 ~ 20 bunches Rep=1.5Hz X emit=2.5E-6( at 0 intensity) Y emit=2.5E-8( at 0 intensity)

  3. Vertical Emittance development Values in Log-book GLC Design: 8.0 x 10-12 at 7.5x109 bunch intensity ATF Goal: Target Y emittance = 1.0 x 10-11 at 0 intensity (normalized Y emi = 2.5 x 10-8 , 1% from X emi ) ATF operation: 21 weeks/year

  4. Low Emittance tuning • Optics modeling by beam based way Q-magnet strength correction in model • Beam based BPM offset measurement Q, SX trim excitation & bump orbit to orbit response • Orbit correction • Dispersion correction • Coupling correction horizontal kick to vertical response, then skew corrector

  5. Improvement by 2µm BPM Vertical dispersion Vertical orbit

  6. X to Y coupling Improvement by 2µm BPM

  7. Twin peaks laserwire use TEM01 resonance mode in the optical cavity as a laserwire good resolution for small beam size factor 2~3 resolution improvement insensitive for beam orbit drift scan free Y. Honda – KEK ATF

  8. ATF Laserwire Precision CW cavity Inside ATF Damping Ring Primary beam size monitor

  9. Transverse Emittance by Laser wire < 0.4% y/x emittance ratio Y emittance =4pm at small intensity

  10. Preliminary result of Fast Ion Instability simulation simulation Behavior of Y emittance is very similar. Schematic of the Fast-Beam Ion Instability

  11. DR vacuum pressure • Low emittance was observed at DR pressure < 4 x10-7 Pa • Emittance growth observed with vacuum pressure > 4 x10-7 Pa, even small bunch charge. ~15 A.hour (ex. 150mA.100hours) 20 bunch, 1 train = 52mA

  12. Bunch by bunch emittance June 2004

  13. Multibunch emittancesummary • Low vertical emittance at low bunch intensity eyn = 1.5x10-8 (6pm at 1.28GeV) vertical emittance at low intensity. (GLC Design2.0x10-8 ) • Blowup at tail was observed Possible reason will be Ion effect. Study and simulation are under way. • Reducing DR vacuum pressure is important DR pressure should be < 4 x10-7 Pa with beam. 15 A.hour more beam exposure is required. bunch-by-bunch feedback like KEK-B, PEP II, is also required.

  14. High Power Generation test stand One more High Power station March 2005 PPM Klystrons for #3 and #4 station April 2004~ SLED II RF pulse compressor April 2005~

  15. Status of #3 station modulator and klystron • Modulator for #3 and #4 soket Inverter charging and conventional PFN are used. Start commissioning in April 2004. 150Hz operation tested at low voltage. Automated control software is under installation. • PPM-5 Klystron Initial processing was done at AR-south. Continuation of processing was started a week ago.

  16. ATF goals for 2004: Multi-bunch emittance ~8pm Extraction line stabilization and nano-BPM studies Initial studies for FONT Extraction line coupling correction Wiggler tests (fall) Student projects: Laserwire Optical diffraction radiation X-ray beamline (3KeV) Polarized positron GLCTA/S-band testing SLAC/LLNL/LBL/UK workers at ATF: December 2003 BBA March 2004 nanoBPM FONT June 2004 nanoBPM FONT Diamond Stray fields ATF visits & operation 04 Late June: G. Blair & D. Howell, UK Laserwire project at ATF

  17. Goals: Reduce ey to ~ 3 pm-rad (now 12 pm-rad) ◙ (gey ~ 7 nm-rad @ low I) Monitor sources of drift Sextupole BBA - innovation Alignment tests Problems: BPM resolution ◙ Sextupole trims weak reproducibility Alignment of combined function bends It is very, very slow ◙ Beam Based Alignment (BBA) 02 Mark Woodley/Janice Nelson/Andy Wolski Two year old slide June 20, 2002

  18. Goals: LOCO Single step (no bump) 1 pm Problems: Sextupole trims weak Alignment of combined function bends BBA 04 Mark Woodley/Janice Nelson/Andy Wolski

  19. Achievements 2004: Installation of LLNL support space frame Fast record monitors from LBNL Thermal stabilization and monitoring Integration with all ATF monitors * Low noise electronics tested on bench and in – situ Many small effects evaluated FONT studies begun… Problems: Controls – EPICS Beam stability Failed kicker system 10um instead of 3-4 um pulse to pulse stability (sigma ~20um) Damaged cavities nanometer resolution BPM 04

  20. X1 X2 X3 Sample pulses showing damaged cavities Cavities retuned (3rd time) by Vladimir Vogel Y1 Y2 Y3 Coupling between x and y  elliptical cavity shape This is a concern for large installations of this type of cavity BPM X1 X2 X3 Y1 Y2 Y3

  21. ATF plans • ATF is the only LC test facility that provides small, stable, electron beams for instrumentation / beam dynamics tests • New programs at ATF include: • KEK nanometer BPM – complementary to BINP/SLAC/LLNL • FONT • UK Laserwire group (Oxford/RHUL) • Stabilization system tests • (vertical incoherent floor motion is a few nm above 0.5Hz in ~5m section of extraction line) • Strong participation from UK universities, SLAC, LLNL, LBNL in addition to Asian institutes • EuroTev beam instrumentation projects also

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