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TESLA Linear Collider project overview and linac technology

The TESLA Collaboration's superconducting linac technology for a 500 GeV e+e- Linear Collider, benefits, challenges, and key components like accelerators, beam delivery, and cavity preparation.

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TESLA Linear Collider project overview and linac technology

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  1. TESLA Linear Colliderproject overview and linac technology R. Brinkmann, DESY ITRP Meeting, RAL Jan. 28, 2004

  2. 500( 800)GeV e+e- Linear Collider Based on superconducting linac technology

  3. The TESLA Collaboration: 54 Institutes from 12 countries MIT (Jan 2004)

  4. Acknowledgement Many thanks to the colleagues from other LC design groups for critical and competent reviews of TESLA design issues! Collaborative effort (e.g. beam dynamics) during TRC process is a step in the right direction

  5. Cost estimate 500GeV LC, one e+e- IP: 3,136 M€(no contingency, year 2000) + ~7000 person years

  6. Why… …technology? • Low RF losses in resonators (Q0 = 1010 ,pure Nb at T=2K) • High AC-to-beam efficiency • Long pulses/many bunches with low RF peak power • Fast intra-train orbit&energy feedback & luminosity stabilisation Low frequency (f=1.3 GHz), small wakefields  f 3 Relaxed alignment tolerances, good beam stability

  7. Accelerating gradient on test stand reached 25 MV/m on average for 1999/2000 cavity production

  8. Higher performance cavities: energy reach  800 GeV 1st step: no add. investment, 2nd step: add cryo+RF power

  9. Site power: 140 MW Linac: 97MW Sub-systems: 43MW RF: 76MW Cryogenics: 21MW Injectors 78% Damping rings Water, ventilation, … Beam: 22.6MW 65% 60%

  10. Main Linac basic unit: 10MW klystron 3 modules with 12 cavities each 3 prototypes delivered from European industry operated at design spec Ongoing: prototypes from two more vendors Per main linac: 286 units, incl. 2% reserve for failure handling

  11. The sub-systems… • Considerable complexity • technical and beam dynamics challenges Damping ring e+ source e- sources Beam delivery

  12. Preparation of Cavities

  13. Search for clusters in Nb sheets. Eddy current system. DESY eddy current scanning apparatus for niobium discs. 100% Nb sheets for TTF scanned and sorted out An eddy current scanning system for Nb sheets can be industrially produced now on basis of DESY and BAM development

  14. Fluorescence analysis Example of the Nb sheet eddy current scanning test. Arrow indicates the suspicious spot.

  15. Exciation Curves for Cavities from the 3rd Production Series TESLA goal TESLA goal 35 Unloaded Quality Factor Q0 30 25 TESLA goal TESLA goal 20 15 Accelerating Gradient ( MV/m ) 10 5 0 High Gradient Performance The First Three Production Series (without electro-polished cavities) <Eacc> [MV/m] Approx. 70 cavities were produced in three production series. Gradient and gradient spread improved a lot. Six accelerator modules with 8 cavities each were assembled. Three of them were used in the TTF Linac. Modules 4 and 5 tests started in autumn 2003. The First Six Accelerator Modules 1 2 3 4 1* 5 Accelerator Module no.

  16. e- beam diagnostics e- beam diagnostics bunch compressor laser driven electron gun undulator photon beam diagnostics pre-accelerator superconducting accelerator modules TESLA Test Facility Linac (Phase-I until 2003) 240 MeV 120 MeV 16 MeV 4 MeV

  17. Total accumulated beam time 13,000h Mainly at 13…17 MV/m (FEL) Several weeks of module 3 at max gradient 30MV/m M5 Test with RF, Q0 = 8109 at 25 MV/m (equal RF power to all cav’s – limitation on acc gradient by cav #8)

  18. week 3 / 2002 FEL User Operation week 7 / 2002 Accelerator Studies Approx. 50% of beam time allocated to FEL operation

  19. Beam operation with module #3 at max. gradient (average of 8 cavities) 22MV/m

  20. 1000 MeV 450 MeV 150 MeV 4 MeV experimental area bypass undulators seeding collimator #7 #6 #5 #4 #3 #2 module #1 RF gun 250 m TTF Phase-II (from 2004) • VUV/soft X-ray FEL user facility down to 6nm wavelength • Operational experience with 5 accelerator modules • Beam test of module with high-performance EP cavities (M6)

  21. Other Test Facilities • PITZ, DESY-Zeuthen: photocathode RF gun (low-emittance beam, mainly FEL-related R&D), n.c. booster cavity (e+ injector prototype) • A0, FNAL: photocathode RF-gun, 9-cell cavity & bunch compressor, diagnostic beam line (low-emittance short bunches, flat beams x>>y, and R&D not related to LC) • RF power input coupler test stand, LAL-Orsay

  22. R&D towards higher energy reach: 1. Superstructure • Increase fill factor by 6% • Reduce # of RF couplers by factor 2 • Test of two prototypes Sept/Oct. 2002: • Frequency tuning no problem, field flatness >90% • Beam test with long bunch trains at 15MV/m, dE/E ~few 10-4 • HOM damping better than TESLA specs

  23. 2. Improvement of Nb surface quality with electro-polishing (pioneering work done at KEK) BCP EP • Several single cell cavities at g > 40 MV/m • 4 nine-cell cavities at ~35 MV/m, one at 40 MV/m

  24. EP facility at DESY, commissioned 2003

  25. CW test of best 9-cell EP-treated (at DESY) cavitynote: no 1400 C titanisation treatment!

  26. CHECHIA test in pulsed mode (two cavities tested to date, similar results) TESLA 500 – 800 design

  27. High Power Test of a complete EP nine-cell cavity Calib.Measurement HERA plant • 1/8th of a TESLA cryomodule • 5 Hz, 500 ms fill, 800 ms flat-top • 35 +/-1 MV/m with no interruption related to cavity-couplerfor more than 1000 hours • No field emission upto 35MV/m, small FE > 35 MV/m • Active compensation of Lorentz force detuning operational for more than 500 hours • Interruptions due to • cryoplant (HERA shutdown, TTF restart) • RF system (power jumps, problem with old LLRF system +modulator) Power/kW Eacc/MV/m

  28. Lorentz force detuning at high-g successfully compensated with piezo-tuner

  29. HH/SH Linear Collider site • Most of preparation work for “Planfeststellungsverfahren” (plan approval, legal procedure for construction permission) has been completed • Will not start formal procedure unless decision/approval process more advanced • LC and XFEL sites are de-coupled

  30. Seismic measurements: Ellerhoop more quiet than HERA (data taken on a Monday, 0.00h – 1.00h) HERA tunnel Ellerhoop (barn)

  31. Tunnel layout being reviewed: Optimise usage of the cross section

  32. The European X-ray FEL project • Update to TDR in Oct. 2002: XFEL with separate linac • Estimated cost 684 M€ (year 2000) including personnel • Approval for construction as European project by German Government Feb. 2003, incl. 50% funding • Discussion with European Partners ongoing at government and laboratories levels • European project organisation in 2005 and start of construction 2006

  33. New site: starting from DESY, 3.3 km towards WNW Seismic measurements

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