Status of X-ray FEL/SPring-8 Machine Construction

Transcription

1 T. Oct 2008 Status of X-ray FEL/SPring-8 Machine Construction Representing JASRI+RIKEN Joint Team T. Shintake RIKEN/SPring-8 Status of 8 GeV XFEL/SPring-8 Construction What we learned from SCSS Test Accelerator 0.7 π.mm.mrad emittance at undulator

2 XFEL/SPring-8 (photo 2007 Summer) T. June GeV SPring-8 Ring since 1997 SCSS Test Accelerator since 2006 Project Period First X-ray Beam E Beam Energy Project Cost Main Accelerator Undulator Hall Experimental Hall 2006 ~ GeV ~360 Oku-Yen 400 m on surface 250 m, 5 lines 56 x 31 m 8 GeV XFEL under construction

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4 Basement Construction (Strengthening foundation) 8 GeV Linear Accelerator (400 m) Soil Soft hardness rock Mid hardness rock Total Number of stakes: 139 Size : 1.5 m ~ 1.6 m Length: average ~30 m (max 52 m) Piling : June ~ October

5 8 GeV XFEL Construction 2008 January T. June 2008 Linac Tunnel Undulator area has been excavated to replace soft soil to hard basement.

6 T. June GeV XFEL Construction 2008 May

7 8 GeV XFEL Construction T. SCSS & XFEL/SPring September Undulator Hall 400 m accelerator Accelerator tunnel Assembly Hall

8 Tunnel Construction 2008 September T. SCSS & XFEL/SPring Undulator Hall 400 m accelerator Steel Mesh & Level Guide Rail Beam Dump

9 Concept of XFEL/SPring-8 Thermionic Electron Gun 8 GeV C-band accelerator In-Vacuum Undulators X-ray Laser Electron Beam SASE-FEL Beam Dump 1) Electron gun Low emittance (εn ~ 0.7π mm*mrad) Higher electron density at the undulator. 2) C-band accelerator High gradient (Ea ~ 35 MV/m) Compact accelerator. 3) In-vacuum undulator Short period (λu ~ 18 mm) Shorter wavelength with lower electron energy.

10 500 kev 1 A x 1 ns 8 GeV XFEL Machine Layout 30 MeV 100 A 400 MeV 1 ka Bunch compression Injector S-band C-band (42 off-crest) V/V ~ 0.01%rms φ ~ 0.2 deg.rms 1.4 GeV 3 ka C-band (crest) Acceleration Ea = 35 MV/m V/V ~ 0.01%rms φ ~ 0.5 deg.rms 8 GeV 3 ka Undulators X-ray Laser λmin < 0.1 nm

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12 T. June 2008 Expected Performance of XFEL/SPring-8 Wavelength Peak Power X-ray Pulse Length X-ray Pulse Energy Photon Flux Peak Brightness Pulse Repetition Bunch per Pulse e Beam Multi-bunch Option < 0.1 nm ~ 20 GW ~ 20 fs 0.4 mj 2 x p/pulse 1 x p/mm 2 /mrad 2 /0.1% BW 10 ~ 60 pps 1 ~ 50 (4.2 nsec spacing) 8 GeV x 0.3 nc 0.8 πmm.mrad, 3 ka 50 x 60 = 3000 pps Expected X-ray pulse of 0.1 nm (SIMPLEX simulation)

13 Gun 238 MHz 476 MHz RF Acceleration System in 8 GeV SPring-8 XFEL Injector L-band s1 S-band 50 MeV 450 MeV s4 T.Shintake 2007 March c C-band Sector-1 BC-0 BC-2 BC-1 c GeV c GeV c2-1 C-band Sector-2 c GeV C-band Sector-3 c3-1 c3-16 C-band Klystron 64 Acc. Str GeV c4-1 C-band Sector-4 c GeV To Undulator

14 C-band RF system

15 400 m Long C-band Main Accelerator

16 T. June 2008 C-band Accelerator for Multi-bunch Option 13,000 cells are under mass production. T. Shintake, Choke Mode Cavity, Jpn. J. Appl. Phys. Vol. 31 pp. L1567-L1570, November 1992 Higher Order Mode Damping for Multi-bunch operation. Maximum 50 bunches x 1 nc, at 4.2 nsec spacing Sadao Miura, MITSUBISHI Heavy Ind, April 2008

17 128 tubes of the C-band Accelerating Structure are in mass-production for 8 GeV linac. T. Shintake@ June 2008

18 C-band accelerator at the prototype accelerator Waveguide from rf pulse compressor Undulators After accelerating structure 120 MeV 250 MeV After rf pulse compressor Peak 200 MW Unit#1 Unit#2 Accelerating structure 1.8 m x 4 colums Klystron output 50 MW Klystron voltage -330 kv Since May 2008 run period, Accelerating gradient = 36.6 MV/m (@unit#2) So far, no trouble, very rare trip rate (rf discharge)

19 RF trip rate in 37 MV/m operation User run (May 2008 ~ July 2008) Total: 299 hours, 10 pps Fault: 26 times Safety interlock 4 Control 2 C-band #2 4 Reason GUN 11 RF trip 2 High voltage 1 Fake interlocked 1 C-band #1 0 S-band 2 Buncher 3 This is acceptable rate for XFEL C-band is stably operated.

20 Klystron Modulator for C-band, S-band 50 MW Klystrons Modulator Mass Production

21 Modulator Mass Production Ship Engine maker KOTOBUKI at AIOI city makes modulator tank. Circuit blocks will be mounted On base plate, which is precisely machined, suitable for mass-production.

22 T. June MW Klystron and Modulator for XFEL Max RF power : 50 and S-band Max Pulse Power: 110 MW Max Rep Rate : 60 pps Size : 1m x 1m x 1.7 m Total Weight : 4.5 ton Insulation oil filled. Water cooled. Perfect EM noise shield. Ready for mass production of 70 units. Pulse Voltage Stability 10 ppm. rms

23 High power test stand PFN HV charger - 50 ppm (p-p) repeatability at PFN voltage Accelerating structure RF pulse compressor Modulator - PFN, thyratron and pulse transformer in one oil tank High power test of rf components - Sample check before installation to XFEL

24 High power test stand for XFEL RF pulse compressor Klystron Accelerating structure Modulator -PFN, thyratron and pulse transformer in one oil tank - good stability for XFEL 50 ppm (p-p) at PFN voltage Combined test of the C-band unit (rf components, klystrons, power supplies, ) which are used at 8 GeV machine.

25 Q-D-V44 Q-D-V44 Electron Beam SP-8 XFEL Undulator Line Undulator Lines Elxperimental Stations Bending Magnet 1.2 m FEL light 5 m ST -D-V44 ST -D-V44 ST -D-V44 ST -D-V44 UND-ID-1 ~110 m 18 Undulator Segments Drift Section GV,PM,CT,BPM Focusing Q Phase Shifter Steering Coils

26 Undulator for XFEL/SPring-8 Takashi Tanaka Magnetic Circuit Hybrid Length Period 5 m 18mm NeFeB Hybrid Number of Periods 276 Gap Minimum 2mm At 1 ope 4mm K-value Max Max At 1 ope 40mm

27 Undulator for 8GeV X-ray FEL SPring-8 Outlook of 5 m long in-vacuum undulator for X-ray FEL. 18mm NeFeB magnet array, undulator period is 18 mm.

28 SAFALI Field Measurement System SAFALI: Self-Aligned Field Analyzer with Laser Instrumentation Simple mover of hole probe. fit within vacuum chamber. Laser beam guide for xy-displacement, and position feedback on guide rail. Laser distance meter for z-location. Takashi Tanaka laser scale corner cube laser diode 2-axis stage rail carriage stepper motor

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30 Field Tuning by SAFALI At unit-1, tuning taper by 2 μm At unit-3, tuning offset by -2 μm Field reproduced the field before installing magnet inside the vacuum chamber Phase Error (degree) (a) σ φ =7.2 o Before Tuning Gap Fine Tuning (b) σ φ =3.3 o After Tuning Pole Number Pole Number

31 SCSS Test Accelerator Performance T. June 2008

32 50~60 nm, 30 μj/pulse Multi-photon absorption. Wavefront distortion measurement. etc. T. June 2008 SCSS Test Accelerator User Run Has been Started in 2008

33 T. June 2008 CeB6 Crystal Cathode has reached its lifetime after 20,000 hour operation. January 2008, right after the new year holiday, the emission current decreased quickly by 50%. It has been nicely running for user experiment till end of December 2007, (60 nm full saturation) This crystal was installed in October Lifetime is 20,000 hours, which is shorter than we expected. But, it is fairly long enough, we decided to regularly change the crystal every year at summer shutdown. It took two weeks to replace cathode and tuning beam to recover full saturated lasing.

34 Single-crystal CeB 6 Cathode for the SCSS Low-emittance Injector 500 kv Electron Gun Heating Cathode Diameter : φ3 mm Temperature : ~1500 deg.c Beam Voltage : 500 kv Peak Current : 1 A Pulse Width : ~2 μs

35 2008/01/28 First experience, but team did nice work. T. June 2008 We replaced CeB6 crystal in SCSS accelerator, after 20,000 hour operation. Anode flange had color change.

36 It was found the cathode surface became concave of 0.2 mm deep from the initial flat surface. It corresponds to evaporation speed of 10 nm/hour ( 10 nm/h x 20,000 h = 200 micron-meter) Concave geometry made beam slightly focusing, but did not break emittance. Electron microscope study showed (1) Surface is fairly smooth, (2) covered by carbon contamination (lowered electron emission). CeB6 cathode after 20,000 hour use. T. Shintake@ June 2008

37 T. June 2008 Cathode Surface EM Image There is no evidence was found by SEM imaging, no carbon contamination. Graphite holder CeB6 After 20,000h operation CeB6 New, before usage CeB6 Material Evaporated, 200 um. Carbon sintered with boron from CeB6

38 T. June 2008 SCSS Test Accelerator Performance Running Always in Saturation Mode 50~60 nm (wavelength is limited by accelerator energy) 30 uj/pulse energy 200 fs pulse length E-beam 250 MeV, 0.4 nc, < 1 psec, 10 pps E-beam Emittance in the undulator is 0.7 π.mm.mrad Determined from FEL gain measurement.

39 SASE Performance at Saturation Item Achieved Performance Wavelength Repetition Rate Pulse Energy Pulse Energy Fluctuation(STD) Laser Size (FWHM)# Pointing Stability# 50~60 nm < 20 Hz ~10% ~3mm ~5% to the beam size 0.6% Averaged Spectrum Width (FWHM) # 10m downstream location of the source point 4

40 FEL test accelerator (2005~ ) To confirm feasibility of 1. Bunch compression for SASE lasing 2. Accelerator components 3. Experiment with FEL light. Total length : 60 m (1/10 of 8 GeV machine) E: 0.5 MeV E: 40 MeV E: 250 MeV 238 MHz PRE-BUNCHER 500 kv PULSED GUN S-BAND LINAC 1 m 2 m 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: 1.3 Gap: 3.7 mm

41 Saturation of SASE Amplification The normalized emittance is estimated to be 0.7πmm.mrad! Exponential Growth Saturation 5

42 Stability of SASE Intensity Intensity variation = 11%(1σ) 50 nm 6

43 T. June 2008

44 HHG Seeding Experiment At SCSS Test Accelerator G. Lambert, LOA ENSTA Palaiseau, France

45 T. June 2008 Summary SCSS Test Accelerator is running fully saturated condition. E-beam Emittance in undulator is around 0.7 π.mm.mrad. This is enough for X-ray FEL at 0.1 nm range. Construction of 8 GeV XFEL/SPring-8 is going well. First X-ray beam : End of FY 2010

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