SCSS Prototype Accelerator -- Its outline and achieved beam performance -- Hitoshi TANAKA RIKEN, XFEL Project Office Oct. 13, 2006 140th JASRI Colloquium presented 1 by Hitoshi TANAKA
Content 1. Light Quality; SPring-8 v.s. XFEL 2. What are the critical issues? 3. Mission of the Prototype Accelerator 4. Unique Features of the Prototype 5. Achieved Beam Performance 6. Towards 8-GeV XFEL Oct. 13, 2006 140th JASRI Colloquium presented 2 by Hitoshi TANAKA
(1/3) 1. SPring-8 v.s. XFEL (1) (Peak) Brilliance of ~10 20 (10 24 ) photons/s/mm 2 /mrad 2 /0.1b.w./100A(5A) (2) 1D Spatial Coherence at the sample (3) Pulse Width of ~40psec (4) High Pulse Rate >200KHz Signal Integration Time-Averaged Steady State Oct. 13, 2006 140th JASRI Colloquium presented 3 by Hitoshi TANAKA
(2/3) 1. SPring-8 v.s. XFEL (1) (Peak) Brilliance of ~10 21 (10 32 ) photons/s/mm 2 /mrad 2 /0.1b.w. (2) 2D Full Spatial Coherence at the sample (3) Pulse Width of ~100fsec (4) Low Pulse Rate, 60Hz Shot-by-Shot Time-Sliced Observation Unsteady State Oct. 13, 2006 140th JASRI Colloquium presented 4 by Hitoshi TANAKA
(3/3) 1. SPring-8 v.s. XFEL XFEL provides users with: (1)Transversally full coherent, (2)short pulsed, (3)ultra-intense probe and exciter in x- ray wavelength regime. Oct. 13, 2006 140th JASRI Colloquium presented 5 by Hitoshi TANAKA
2. What are the critical issues? (1/3) FEL Interaction Image Undulator Field v e z E x EM Field by Radiation Electron Orbit v e E x v e E x Oct. 13, 2006 140th JASRI Colloquium presented 6 by Hitoshi TANAKA
2. What are the critical issues? (2/3) S N S N S N S N S ∼λ =1Å N S N S N S N N S The density modulation of λ -scale is necessary for achieving the amplified undulator radiation. Oct. 13, 2006 140th JASRI Colloquium presented 7 by Hitoshi TANAKA
2. What are the critical issues? (3/3) (1) Generation of high quality electron beam with small emittance and high peak current (2) Ultimate stability of electron beam (3) Precise overlap of electron beam and undulator radiation (4) Measurement of slice emittance, etc Oct. 13, 2006 140th JASRI Colloquium presented 8 by Hitoshi TANAKA
3. Missions of the Prototype (1/2) SPring-8 Compact SASE Source (SCSS) adopts three unique systems; a low emittance injector with 500 kV pulsed electron gun, C-band accelerator, and in- vacuum undulator. The prototype is a test-bench to confirm the performance of each system. Oct. 13, 2006 140th JASRI Colloquium presented 9 by Hitoshi TANAKA
3. Missions of the Prototype (2/2) The biggest question is whether "emittance conservation" through the injector is a sufficient level or not under the practical error condition. Only the experimental results can answer the above and verify the validity of the injector system. Oct. 13, 2006 140th JASRI Colloquium presented 10 by Hitoshi TANAKA
Unique Features (1/7) Schematic View Oct. 13, 2006 140th JASRI Colloquium presented 11 by Hitoshi TANAKA
Unique Features (2/7) Picture from the E-gun Oct. 13, 2006 140th JASRI Colloquium presented 12 by Hitoshi TANAKA
4. Unique Features (3/7) 4.1. Specially Designed In-vacuum Undulator Period: 15mm Length: 4.5m Period No. : 300 Material: NdFeB Min.Gap: 2mm 45-deg. Tilted Magnet Configuration K-value: 1.8@MinG Oct. 13, 2006 140th JASRI Colloquium presented 13 by Hitoshi TANAKA
4. Unique Features (4/7) 4.2. C-band Accelerator System initially developed for JLC was used. f RF : 5.7GHz Gradient: 32MV/m RF Power: 53MW Accel. Unit Length: 1.8m RF Pules Width: 2.5 µ sec Oct. 13, 2006 140th JASRI Colloquium presented 14 by Hitoshi TANAKA
4. Unique Features (5/7) Schematic View of C-band Accelerator System Oct. 13, 2006 140th JASRI Colloquium presented 15 by Hitoshi TANAKA
4. Unique Features (6/7) 4.3. Low Emittance Injector with 500kV pulsed E- gun World Standard: Photo-cathode RF-gun based system Most of accelerator physicists at the inside and outside of SPring-8 were negative against the SCSS injector system. Oct. 13, 2006 140th JASRI Colloquium presented 16 by Hitoshi TANAKA
4. Unique Features (7/7) Beam Energy 500keV Peak Current 1~3A 2 µ sec Pulse Width (FWHM) Repetition Rate 60Hz Cathode Diameter 3mm 1400~1600 ° C Cathode Temperature Cathode Material CeB 6 0.4 π mm.mrad Theoretical Thermal Emittance (rms) 0.6 π mm.mrad Measured Normalized Emittance (rms, 90% particles) Oct. 13, 2006 140th JASRI Colloquium presented 17 by Hitoshi TANAKA
5. Beam Performance (1/6) First SASE lasing at 49nm was successfully observed in June this year. The lasing data showed that the achieved “beam brilliance” reaches to the target value, 200A/ π 2 mm 2 ⋅ mrad 2 . Oct. 13, 2006 140th JASRI Colloquium presented 18 by Hitoshi TANAKA
5. Beam Performance (2/6) Prototype Target v.s. 8GeV XFEL Target Prototype: Peak Current=800A Normalized Emittance=2 π mm.mrad 8GeV XFEL: Peak Current=3kA Normalized Emittance=1 π mm.mrad Oct. 13, 2006 140th JASRI Colloquium presented 19 by Hitoshi TANAKA
5. Beam Performance (3/6) 5.1. Electron Beam Brilliance(1) 1000 •Angular photon flux Ratio(Coherent/Spontaneous) 1500A 832A v.s. K-value with ID#1. 1250A 750A 1070A Meas. 100 937A •270~315 Q=0.25nC ε =2 π mm.mrad π 2 mm 2 ⋅ mrad 2 10 σ δ E/E =0.001 estimated by 3D-FEL simulator SIMPLEX. 1 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 K Value Oct. 13, 2006 140th JASRI Colloquium presented 20 by Hitoshi TANAKA
5. Beam Performance (4/6) 5.1. Electron Beam Brilliance(2) 10 1 •Radiation Intensity y=a ∗ x 1/2 exp(b ∗ x 1/3 )+c ∗ x v.s. peak current with Experiment Intensity (a.u.) ID#1 and ID#2. Fitting Curve 10 0 •240 π 2 mm 2 ⋅ mrad 2 estimated by 1D-FEL model. 10 -1 0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28 Electron Beam Charge (nC) Oct. 13, 2006 140th JASRI Colloquium presented 21 by Hitoshi TANAKA
5. Beam Performance (5/6) 5.2. Lasing Stability 2.5 •Good reproducibility of Ave.=0.96 µ J/pulse 1 σ =0.43 µ J/pulse(~45%) SASE lasing by 2 reloading machine E( µ J/pulse) 1.5 parameters. 1 0.5 0 0 5 10 15 20 25 30 Time (sec) Oct. 13, 2006 140th JASRI Colloquium presented 22 by Hitoshi TANAKA
5. Beam Performance (6/6) 5.3. Beam Stability 200 • Orbit Stab.(1 σ ) @ID σ x =13 µ m Hori. Vert. 150 σ y =21 µ m ~1/5~1/10 of beam size Frequency 100 • Energy Stab. (1 σ ) 50 ~0.06%@250MeV 0 -0.1 -0.05 0 0.05 0.1 Devitation ∆ [mm] Oct. 13, 2006 140th JASRI Colloquium presented 23 by Hitoshi TANAKA
6. Towards 8-GeV XFEL (1/3) The experimental results show that PARMELA gives a good design guideline in our case and conclude that the beam performance for x-ray FEL is reachable by the smooth extension of the prototype accelerator. Oct. 13, 2006 140th JASRI Colloquium presented 24 by Hitoshi TANAKA
6. Towards 8-GeV XFEL (2/3) The remaining issues: • Optimization of multi-stage bunch compression system • Improvement of inverter PS • Precise timing system • Alignment scheme for photon and electron beam along undulators • etc Oct. 13, 2006 140th JASRI Colloquium presented 25 by Hitoshi TANAKA
6. Towards 8-GeV XFEL (3/3) Oct. 13, 2006 140th JASRI Colloquium presented 26 by Hitoshi TANAKA
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