SCSS Prototype Accelerator -- Its outline and achieved beam - - PowerPoint PPT Presentation

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 1

SCSS Prototype Accelerator

• - Its outline and achieved beam

performance --

Hitoshi TANAKA RIKEN, XFEL Project Office

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 2

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 by Hitoshi TANAKA 3

• 1. SPring-8 v.s. XFEL

(1) (Peak) Brilliance of ~1020 (1024)

photons/s/mm2/mrad2/0.1b.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

(1/3)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 4

(1) (Peak) Brilliance of ~1021 (1032)

photons/s/mm2/mrad2/0.1b.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

• 1. SPring-8 v.s. XFEL

(2/3)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 5

• 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.

(3/3)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 6

• 2. What are the critical issues?

ve ve ve z Electron Orbit Undulator Field Ex EM Field by Radiation Ex Ex

FEL Interaction Image

(1/3)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 7

S S S S S N N N N S S S S N N N N N

The density modulation of λ-scale is necessary for achieving the amplified undulator radiation.

• 2. What are the critical issues?

∼λ=1Å (2/3)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 8

• 2. What are the critical issues?

(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 (3/3)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 9

• 3. Missions of the Prototype

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.

(1/2)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 10

• 3. Missions of the Prototype

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.

(2/2)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 11

Unique Features (1/7)

Schematic View

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 12

Unique Features (2/7)

Picture from the E-gun

• Oct. 13, 2006

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• 4. Unique Features (3/7)

4.1. Specially Designed In-vacuum Undulator

45-deg. Tilted Magnet Configuration

Period: 15mm Length: 4.5m Period No. : 300 Material: NdFeB Min.Gap: 2mm K-value: 1.8@MinG

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 14

• 4. Unique Features (4/7)

4.2. C-band Accelerator System initially developed for JLC was used. fRF: 5.7GHz Gradient: 32MV/m RF Power: 53MW

• Accel. Unit Length:

1.8m RF Pules Width: 2.5µsec

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 15

• 4. Unique Features (5/7)

Schematic View of C-band Accelerator System

• Oct. 13, 2006

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• 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

• utside of SPring-8 were negative against the

SCSS injector system.

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 17

• 4. Unique Features (7/7)

0.6πmm.mrad

Measured Normalized Emittance (rms, 90% particles)

0.4πmm.mrad

Theoretical Thermal Emittance (rms)

CeB6 Cathode Material 1400~1600°C Cathode Temperature 3mm

Cathode Diameter

60Hz

Repetition Rate

2µsec

Pulse Width (FWHM)

1~3A

Peak Current

500keV

Beam Energy

• Oct. 13, 2006

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• 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/π2mm2⋅mrad2.

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 19

• 5. Beam Performance (2/6)

Prototype Target v.s. 8GeV XFEL Target Prototype: Peak Current=800A Normalized Emittance=2πmm.mrad 8GeV XFEL: Peak Current=3kA Normalized Emittance=1πmm.mrad

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 20

• 5. Beam Performance (3/6)

5.1. Electron Beam Brilliance(1)

• Angular photon flux

v.s. K-value with ID#1.

• 270~315

π2mm2⋅mrad2 estimated by 3D-FEL simulator SIMPLEX.

1 10 100 1000 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1500A 1250A 1070A 937A 832A 750A Meas. Ratio(Coherent/Spontaneous) K Value Q=0.25nC ε=2πmm.mrad σδE/E=0.001

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 21

• 5. Beam Performance (4/6)

10-1 100 101 0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28 Experiment Fitting Curve Intensity (a.u.) Electron Beam Charge (nC) y=a∗x1/2exp(b∗x1/3)+c∗x

• Radiation Intensity

v.s. peak current with ID#1 and ID#2.

• 240 π2mm2⋅mrad2

estimated by 1D-FEL model.

5.1. Electron Beam Brilliance(2)

• Oct. 13, 2006

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• 5. Beam Performance (5/6)
• Good reproducibility of

SASE lasing by reloading machine parameters.

5.2. Lasing Stability

0.5 1 1.5 2 2.5 5 10 15 20 25 30 E(µJ/pulse) Time (sec) Ave.=0.96µJ/pulse 1σ=0.43µJ/pulse(~45%)

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 23

• 5. Beam Performance (6/6)

5.3. Beam Stability

50 100 150 200

• 0.1
• 0.05

0.05 0.1 Hori. Vert. Frequency Devitation ∆ [mm] σ

x=13µm

σ

y=21µm

• Orbit Stab.(1σ) @ID

~1/5~1/10 of beam size

• Energy Stab. (1σ)

~0.06%@250MeV

• Oct. 13, 2006

140th JASRI Colloquium presented by Hitoshi TANAKA 24

• 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

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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
• 6. Towards 8-GeV XFEL (2/3)

• Oct. 13, 2006

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• 6. Towards 8-GeV XFEL (3/3)