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C. Christou, M. Dehler. Summary of Working Group 1 Linear Colliders and Light Sources. Goals: Review state of the art in linear colliders and light sources Applicability of X band structures as basic building blocks Demands for X band power sources and accelerating structures.
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C. Christou, M. Dehler Summary of Working Group 1Linear Colliders and Light Sources
Goals: • Review state of the art in linear colliders and light sources • Applicability of X band structures as basic building blocks • Demands for X band power sources and accelerating structures
One dedicated session heavily concentrated on light sources (3 presentations), one lost sheep from WG2 • Global joint session, our special focus X band sources, availability and cost • Joint with WG4: Standard components
RF Systems Booster: 500MHz 1 x 5 cell Cu PETRA cavity1 x 60kW IOT Storage ring: 500MHz 3 x 1 cell Nb Cornell cavities3 x 300kW IOT complex Linac: 3GHz 2 x 5.2m Cu DESY structures 2 x 35MW klystronsbunchers Cavities from Accel. Amplifiers from Thales
Beamtime Statistics (to end Sep.) 2008: 3177h delivered with 95.0% uptime, MTBF = 14.6 h 2007: 3120h delivered with 92.4% uptime, MTBF = 10.0 h
The UK’s New Light Source Project Project to consider the scientific case and develop a conceptual design for a possible next generation light source based on a combination of advanced conventional laser and free-electron laser sources. • STFC Daresbury and Rutherford Laboratories • Accelerator Science and Technology Centre (ASTeC) • Central Laser Facility (CLF) • Diamond Light Source • John Adams and Cockcroft accelerator institutes • Various Universities • NLS Progress • Official Launch, April 11th 2008 • Science Workshops, May 13th – June 19th • Draft Science Case published, Sep. 11th • Science Case approved by the Physical And Life Science committee of the STFC, Oct. 17th approval to proceed to the design stage www.newlightsource.org
NLS: normal conducting option S-band for acceleration X-band for phase space linearisation at input to BC1
NLS: superconducting option Possible SRF Linac Parameters for NLS
Upgrade Paths • Higher photon energies, ≥ 1.5 keV – additional linac • Increased rep. rate, ≥ 10 kHz – VHF/SC gun • Longitudinal coherence to ≥ 1 keV – improved seeding sources • Shorter pulses, ≤ 1 fs – slicing/single-spike • Additional FELs/experimental stations • Latest News • NLS Project Governing Body agreed on Nov. 19th to proceed with the cw superconducting option. • Studies will now concentrate on both the straight and recirculating SC linac options, with 1 keV baseline photon energy.
4th Generation Machines Worldwide Blue – single-stage Red – multi-stage (inc. harmonic correction) Yellow – ERL (various methods) Bold – they have measured that bunch length NLS SC Design NLS NC Design • Users want 1kHz rep. rate, 20fs pulses, 3 GeV ideally • Our initial interpretation, a ~1 GeV SC linac, upgradable to 3 GeV • Other approach, a 3 GeV NC linac (R. Bartolini) • Recirculating option being developed
Similar Schemes to a SC NLS WiFEL Both about 2 GeV Both about 600 m (facility) LBNL
An NLS SC Design (Hywel Owen and Peter Williams) • 735 MeV chosen as it corresponds to 1 nm, the limit for HHG seeding i.e. this is a possible extraction energy where we want short bunches • Compression scheme must be carefully designed – linearisation, cavity wakefield compensation, CSR, LSC • 200 pC bunch charge chosen, based injector on XFEL • EPAC08: MOPC034, MOPC035 available at www.jacow.org • PR-STAB in preparation
Why superconducting in the UK? ‘Mega-facilities’ already under construction – LCLS, XFEL, SCSS, with different pulse patterns, but all ‘low rep. rate’. Provide short wavelength output c. 1 A. Lower-energy ‘low rep. rate’ facilities already operating, under construction or proposed – FLASH, FERMI, MAXLAB etc. Low rep. rate machine (e.g. up to 400 Hz) can use NC cavities, e.g. S-band, C-band, using established technology – therefore cheap, but not competitive • User advantages of SC all from higher rep. rate • Bunch properties about the same • Synchronisation might be easier • Experiments faster, or different ones possible • Disadvantages: • Greater Capital cost (about 1.7 times cf. NC on NLS) • Cryoplant • Lower gradient than C-band (about the same as S-band) – up to 20 MV/m • An X-band solution should compete on: • Higher gradient • Lower cost cf. SC • Rep. rate higher than 1 kHz to compete against S-band • At lower energies, want all X-band to minimise facility length • Wakefields an issues for short bunch production (important)
FERMI@Elettra Linac Experimental Hall Spreader & FEL Hall • Financed by • MIUR • FVG Region • EIB
FERMI objectives Construction of a single-pass FEL User Facility, in the soft X-ray region, based on the existing Normal Conducting S-band Linac. • Beam energy 1.2 GeV (Phase I), 1.5 GeV (Phase II) • 10-50 Hz pulse repetition rate, 1 e-bunch/pulse • Seeded operation with Harmonic Generation • Spectral range: • Phase I 100 (80) – 40 (20) nm, single stage • Phase II 40 (20) – 10 (5) nm, two stages • Short sub-ps pulses 200 fs • Flexible polarization, gap tuning, apple type undulators
LCLS TUE APS 1.6 cell 2.6 cell 1.0 HOM FERMI machine layout X-Band structure Laser heater E~100 MeV E3=1200/1500 MeV 7 nose cone BW_TW 3/4 p (6.1 m) with Sled 9 Slac type FW_TW 2/3 p (3.0 - 4.5 m) without Sled
Firstphotoelectrons Courtesy of M. Trovo’
Cost discussion • Main cost driver is klystron • Usual economies of scale apply • Price starts coming down over 10 units • CLIC will require larger number of X-band klystrons for testing, commissioning… • Specification still not standardised