Current status of XFEL/SPring-8 project and SCSS test accelerator Takahiro Inagaki for XFEL project in SPring-8 inagaki@spring8.or.jp
Outline (1) Introduction (2) Key technology for compactness (3) Key technology for stability (4) Operation status of SCSS test accelerator
Where is SPring-8? Shanghai Osaka Tokyo SPring-8 100 km west of Osaka
SPring-8 campus, 4 photon sources XFEL 8 GeV, 0.1 nm 2011 ~ (plan) Storage ring 8 GeV 1997 ~ 700 m New SUBARU (Storage ring) 1.5 GeV 1998 ~ SCSS test accelerator 250 MeV, 50-60 nm 2005 ~
Expected performance of XFEL/SPring-8 Wavelength Peak Power X-ray Pulse Length X-ray Pulse Energy Photon Flux < 0.1 nm ~ 20 GW 200 fs ~ 20 fs Max 0.4 mj 2 x 10 11 p/pulse Peak Brightness 1 x 10 33 p/mm 2 /mrad 2 /0.1% BW Repetition e Beam ~ 60 pps 8 GeV x 0.3 nc 0.8 πmm.mrad, 3 ka Expected X-ray pulse of 0.1 nm (SIMPLEX simulation)
XFEL project team in SPring-8 More than 100 members
(1) Introduction (2) Key technology for compactness (3) Key technology for stability (4) Operation status of SCSS test accelerator
Concept for Compact XFEL T. Shintake et al, Proc. SPIE 4500 (2001) p.12 1) Short-period Undulator Short period (λu) Lower beam energy (γ) In-vacuum undulator λ = λ ( 2 ) 2 1 K / 2 / 2nγ u + 2) High-gradient Linac Higher frequency for higher power efficiency 3) Low-emittance Electron Injector Need for short gain-length of SASE-FEL. ε = ε n βγ C-band linac (5712 MHz) Single-crystal thermionic gun + Stable bunch compression
CeB6 single-crystal thermionic gun K. Togawa, PRST-AB 10-020703 (2007) Cathode -CeB6 single crystal - Φ3 mm - Lifetime ~ 2 years -Low emittance ~0.6πmm mrad -Uniform profile -Stable, maintenance free -500 kv High voltage tank Profile of the beam 1 μsec Cathode voltage -500 kv Beam ~ 1 A Heated to 1500 C
L-band S-band BC1 BC2 C-band BC3 C-band 8 GeV 3 ka Magnetic compression (chicane) 500 kev 1 A Velocity bunching (< several MeV) T. Shintake, EPAC08-MOPC031
C-band (5712 MHz) accelerator in XFEL tunnel Details are introduced in the afternoon session -High gradient:35 MV/m -HOM absorber for multi-bunch From 400 MeV to 8 GeV -Active length: 250 m -128 accelerating structures -64 klystron units
Klystrons and power supplies should be compact Klystron 50 MW Compact Modulator -350 kv 110 MW 4 cabinets -Timing - LLRF - rf amplifier - PLC control - - Inverter-type HV charger 4 m / 1 unit
In-vacuum Undulator T. Tanaka,. -Short period lower electron energy -Variable gap tunable wavelength 18 segments (~ 100 m) will be installed in BL3. Type Active length Period (λu) Magnetic circuit Planar 5 m / segment 18 mm Hybrid (NdFeB+Permendur) K Maximum 2.2 Gap Minimum 3.5 mm
(1) Introduction (2) Key technology for compactness (3) Key technology for stability (4) Operation status of SCSS test accelerator
Higher bunch compression higher rf stability BC1 BC2 BC3 L-band ΔV/V ~ 0.01%rms Δφ ~ 0.06 (120 fs) S-band ΔV/V ~ 0.01%rms Δφ ~ 0.1 (100 fs) C-band (0ff-crest) ΔV/V ~ 0.01%rms Δφ ~ 0.2 (100 fs)
Pulse-to-pulse jitter from the klystron voltage Accel. Struct. XFEL requires (STD) - Intensity ±100 ppm - Phase ± 0.2 Pulse Comp. RF 70 MW 2 RF 50 MW Klystron Pulse -350 kv Modulator ± 100 ppm ± 100 ppm Charging 50 kv HV Charger AC 420 V Precise HV charger Voltage stability ~ 10 ppm (STD)
Temperature stabilization of LLRF and timing signal N. Hosoda, IPAC10-TUPE024 VME (D/A, A/D, Trigger) LLRF (modulator, detector) Solid state rf amplifier (klystron driver, water cooled) Water cooled cabinets Air cooled cabinets
Electron beam monitors S. Matsubara, IPAC10-MOPE004 OTR profile monitors ~ several μm Cavity BPM ~ 0.2 μm Current monitor - High precision and high reliability - Feedback control of the beam properties; energy, peak current, trajectory,...
Production & Construction Status Building (2006~2009) Accelerator (2007~2010) Kly. gallery (2007~2010) Undulator (2008~2010) Schedule Autumn 2010 ~ RF processing Beginning of 2011 ~ Beam commissioning
(1) Introduction (2) Key technology for compactness (3) Key technology for stability (4) Operation status of SCSS test accelerator
SCSS test accelerator (2005 ~) Total length: 60 m S-band APS and TWA Bunch compressor 2 units of C-band accelerator 238 MHz pre-buncher 476 MHz booster 500 kv electron gun CeB6 thermionic cathode In-vacuum undulators
Characteristics of Electron Beam K. Togawa, PAC09-TH3PBI02 Energy Charge Peak Current Bunch Width Rep. Rate Initial Emittance (normalized, rms) Electron Beam 250 MeV 0.3 nc 300 A 0.7 ps 60 pps (max.) 0.6π mm mrad (90%-core) Transverse Profile OTR monitor at C-band linac exit
Stable EUV photon beam is delivered to user experiments Wavelength: 50-60 nm Pulse energy: 30 μj typical Power Fluctuation: ~10 % K. Togawa, PAC09-TH3PBI02 Transverse Profile 5 mm measured by Si photodiode measured by Ce:YAG screen
Summary Compact XFEL has been constructed in SPring-8 site, based on 3 key technologies. Low emittance thermionic gun & injector High gradient C-band accelerator Short period in-vacuum undulator In order to provide stable laser light, we carefully developed, Precise HV charger for klystron voltage stabilization Temperature stabilization of LLRF and timimg Precise electron beam monitors for the feedback control SCSS test accelerator has provided stable EUV laser to user experiments.
Spare slides
XFEL machine configulation 500 kev 1 A x 1 ns Injector 30 MeV 100 A S-band 4 units 400 MeV 1 ka Bunch compression C-band (42 off-crest) 12 units 1.4 GeV 3 ka Acceleration C-band (crest) 52 units 8 GeV 3 ka Undulators X-ray Laser λmin < 0.1 nm
Bunch compression K. Togawa, PRST-AB 12-080706 (2009) 1428 MHz APS accelerator 476 MHz booster 238 MHz pre-buncher BC1 (chicane) 5712 MHz correction 1428 MHz APS accelerator Velocity bunching < several MeV 3 magnetic compressions BC1 at 30 MeV BC2 at 400 MeV BC3 at 1.4 GeV
C バンドのシステム図
C-band (5712 MHz) accelerator in XFEL tunnel RF pulse compressor 50 MW 2.5 μs -High gradient: 35 MV/m -HOM absorber for multi-bunch Choke-filter SiC absorber 150 MW 0.5 μs 70 MW 0.5 μs Acceleration gradient 35 MV/m 1.8 m-long accelerating structure Details are introduced in the afternoon session Cavity
Construction schedule of the XFEL accelerator FY 06 FY 07 FY 08 FY 09 FY 10 FY 11 Building Now Accelerating structures and waveguide systems ED Production Installation Klystrons and modulators Klystron Modulator Production Installation Control cabinets and low level rf systems Undulators Commissioning Production Installation Production Installation High power rf Commissioning
SCSS test accelerator (2005~ ) 2005 Construction 2006 SASE lasing at 49 nm Seeded FEL at 160 nm 2007 SASE saturation at 50 ~ 60 nm EUV experimental facility building E: 0.5 MeV 500 kv PULSED GUN Velocity Magnetic bunching compression 1 A 100 A peak 238 MHz PRE-BUNCHER S-BAND LINAC 1 m 2 m 300 A peak E: 40 MeV E: 250 MeV C-BAND LINAC UNDULATOR L: 9 m (4.5 x 2) USER AREA BEAM DEFLECTOR 476 MHz BOOSTER Acc: 1.8 m x 4 Kly: 50 MW x 2 λu: 15 mm Kmax: 1.5 Gap: 3 mm Total length : 60 m (1/10 of 8 GeV machine)
Saturation of the SASE amplification T. Shintake et al, Nature Photonics 2 (2008) p.55 Change the undulator gap Instead of change the undulator length Experimental data analyzed by 3D-FEL code SIMPLEX SIMPLEX is produced by T. Tanaka http://radiant.harima.riken.jp/simplex/index.html Small K Large Gap Large K Small Gap Normalized Emittance = 0.7π mm mrad!
Characteristics of EUV Photon Beam EUV Photon Beam (SASE) Wavelength 50-60 nm Pulse Energy 30 μj typical Power Fluctuation ~10% Spot Size* 3 mm (FWHM) Pointing Stability* 5% of spot size Averaged Spectrum Width 0.6% (FWHM) K. Togawa, PAC09-TH3PBI02 * 10m downstream from the undulator