C-band Accelerator systemfor XFEL / SPring-8

C. Kondo, T. Inagaki, T. Shintake

for XFEL project in SPring-8

6/Oct/2008Seminar at SLAC

ckondo@spring8.or.jpinagaki@spring8.or.jp

8 GeV XFEL Machine Layout

InjectorS-band4 units C-band (42 off-crest) 12 units

C-band (crest) 52 units

Undulators

30 MeV100 A

500 keV1 A x 1 ns

1.4 GeV3 kA

8 GeV3 kA

400 MeV1 kA

Bunch compression

Acceleration

X-ray Lasermin < 0.1 nm

Ea = 35 MV/m

V/V ~ 0.01%rms

~ 0.2 deg.rms

V/V ~ 0.01%rms

~ 0.5 deg.rms

C-band (5712 MHz) RF system

HV Charger HV Charger

Pulse-to-pulse jitter from the klystron voltage

HV Charger

AC 420 V

XFEL requires (rms) - Intensity 0.01% - Phase 0.2 °

Modulator

Charging 50 kV

Klystron

Pulse -350 kV

Pulse Comp.

RF 50 MW

RF 70 MW 2

Accel. Struct.

0.01 %

0.01 %high precision HV charger with <0.01% (100 ppm) stability

Improvement of High Voltage Charger

Specification:・ Switching device IGBT・ Charging voltage Max. 50 kV・ Charging current 　 ~ 2 A・ Average output power 　 36 kW・ Repetition 　 60 Hz・ Voltage stability (jitter) 　 0.01 %rms

Aug. 2006, Nichicon Corp.Used at prototype acc.

Feb. 2008, Nichicon Corp.

Nov. 2007, Toshiba electro-wave,

Block Diagram of HV Charger

Full-wave rectification

AC420 V

Full bridgeswitching

Main

Sub

ResonanceHigh voltagerectification

DC600 V

Max. 50 kV

We use Main charger and Sub charger.“Main” charges 99.5%, fast but roughly“Sub” charges up to the target voltage, slowly but accurately.

Feedback Control of Charged Voltage

HV charger Modulator

PFN 　 Capacitors

HV probeJapan finechem inc. 2007

Feedback of the voltage

Error amp.

Reference voltage

Stray capacitance delays the responseMain resistor : 1 G→100 M・ Time constant: 1 msec→100 sec・ Heat loss: Fluorinert, Cooling water.

New HV charger with 10 ppm (rms) stability

Prototype modelFeb. 2008, Nichicon Corp.

This stability satisfies the requirement at XFEL (<100 ppm).

Typical HV charging cycle(Tens of waveforms are overlaid)

C-band (5712 MHz) RF system

Compact “all-in-one” modulator Compact “all-in-one” modulator

“New” modulatorOne tank including the pulse transformer and modulator

Pulse Transformer

PFN circuitCapacitor x16

(General Atomics)

Thyratrone2v CX-1836

EOL circuitDiode & Resistor

Klystroncathode

Nihon Koshuha Co. Ltd., Oct./2007Compact size: 1.7m x 1m x 1.2m, EM noise shielding, etc.

Thyratron and PFN Circuit (Detail)

Thyratron　 e2v, CX-1836・ Deuterium filled・ Impregnated cathode・ Double gap, twin trigger

・ Cooled by natural oil flow Omit forced oil flow.

Pulse Forming Network circuit ZPFN = 4 ・ Capacitor : General Atomics, Max. 50 kV 0.029 F ×16 series・ Coil 　 　 　 　 　　 0.6 H ×16 series

Replace

Other circuit EOL, tail clipper, shunt diode, discharging resistor, etc

Pulse Transformer (detail)

RISHO Co. (Japan)

Turn ratio: 1:16　　　（ Prim=6 turn 、 Sec=96 turn ）Primary voltage: -22 kVSecondary voltage: -350 KV

Epoxy-molded winding　・ High voltage insulation　・ Suppression of wire vibration

Oil cooling system of the modulator

• Concept• Fan-less cooling for viscous insulation oil• Low cost, Compact

• Requirements• Heat generation: ~3kW

• Heater ~1kW ( thyratron cathode, Klystron cathode)• Current loss ~2kW @ 45kV,60pps ( EOL, thy. Anode, Core Loss,

etc)

• Oil temperature : < 45 ℃• We measured the practical heat transfer coefficient

by model tank.• And, we designed the optimum cooling system for the

modulator.

View of Cooling system

2 panel type on partition wall

Cooling panel

1 pipe type on top board

Cooling pipe

2 panel type on side board

Cooling panel (side board)

Oil temperature

Oil temperature on nominal operation

Operation: 45 kV charging 60 ppsCooling water: 26 ℃, 8 L/min

Oil temperature: 　　　　　　　　　 < 43 ℃

Oil

Te

mp

era

ture

(℃

)

C-band (5712 MHz) RF system

C-band Klystron C-band Klystron

50MW pulse klystron

Output power : 50 MW

Frequency: 5712 MHz

RF pulse width: 2.5 sec

Beam Voltage: -350 kV

Beam Current: 310 A

Repetition: 60 pps

TOSHIBA ELECTRON TUBES & DEVICES CO.LTD.

Model No. E37202

In the test accelerator, no trouble for 3,000 hours

C-band (5712 MHz) RF system

Pulse compressorPulse compressor

C-band accelerator structureC-band accelerator structure

RF pulse compressorFabricated by Mitsubishi

Heavy Industries Ltd.

High-Q cavities mode: TE0,1,15

Q0 : 190,000 : 9.5

Mode converters (Shintake 1996) - Waveguide(TE10) Circular(TE0,1,x) - 4 coupling holes Lower rf field at the coupling hole

Input

50 MW

2.5 s

200 MW peak

0.5 s

Output

Directional coupler

Accelerating structure(Shintake structure)

Choke mode cavity (Shintake 1992) - traps the accel. mode (5712 MHz) - eliminate HOM (not 5712 MHz)

multi-bunch operation

High acceleration gradient R~ 54 M/m, ~ 0.53, L=1.8 m Ea = 35 MV/m with 63 MW x 300 nsec rf power

Fabricated by Mitsubishi Heavy Industries Ltd.

19.7

SiC absorber

Mass production of the accelerating structure@ Mitsubishi Heavy Industries Ltd.

Precise lathe

Shipping

Dr. Miura(Mitsubishi)

Cells

High power rf test bunker (July 2008 ~)

Accel. struct. Waveguide RF pulse compressor Modulator Klystron

In order to check quality of the delivered components, we constructed the test bunker. Now, rf processing is in progress.

Modulator development team

白澤近藤櫻井

稲垣武部

新竹

T. Inagaki

C. Kondo

T. Shintake

S. Indo

K. Nakajima

T. Sakurai K. Shirasawa

Summary

Highly precise charger • Parallel charging system• New HV probe of fast response-time.• Stability of charging voltage ~10 ppm (rms)

New “all-in-one” modulator power supply• Compact oil-filled power supply.• EM noise shielding, fan-less oil-cooling system …• No trouble operation for 700 hours

Schedule• High power rf components were delivered on schedule.• Quality will be checked at the rf test bunker.• 2009~2010 installation• 2011~ Beam commissioning

Thank You!