Recent Status of Linac Facility at Osaka University

A.Saeki

Prof. S.Tagawa group: (Beam Material Science)S.Seki, T.Kozawa, K.Kobayashi, K.Okamoto, A.Saeki

Prof. G.Isoyama group: (Accelerator Science)R.Kato, Y.Honda, S.Kashiwagi, N.Kimura

Prof. T.Majima group: (Molecular Excitation Chemistry)M.Fujitsuka, N.Ichinose, S.Tojo, K.Kawai

Prof. Y.Yoshida group: (Beam Science for Nanofabrication)J.Yang

Technician:S.Suemine, T.Yamamoto

Outline1. Recent renewal of linac facility2. S-band photocathod RF-gun linac3. Pulse radiolysis

1

1. Recent renewal of linac facility

Prof. G.Isoyama group:R.Kato, Y.Honda, S.Kashiwagi

Technician:S.Suemine, T.Yamamoto

2

38 MeV, L-band linac 150 MeV, S-band linac

30 MeV, S-band photocathod RF-gun linac

Pulse radiolysisFEL, SASEPositronium Annihilation Lifetime Spectroscopy

Used for

Three linacs 3

Recent renewal

• RF system– Klystron– Pulse modulator for the klystron– Wave guide system– Three amplifiers for the sub-harmonic buncher system– Master oscillator

• Magnet system– Power supplies for the Helmholtz coils, the bending magnets, the quadrupole

magnets, steering coils.• Computer control system• Timing system• Facility

– Interlock system for radiation safety– High precision cooling water system (< ±0.03 °C )– High precision air conditioner for the klystron room– AVR for the AC200V line for the klystron modulator

4

• Previous system– 5 MW klystron (Toshiba,

E3775A) for the prebuncherand the buncher

– 20 MW klystron (Thomson, TV-2022A) for the acceleration tube.

• New system– 30 MW klystron (Thales, TV-

2022E) for the all.

Klystron 5

• Vmax = 295 kV, Imax = 275 A• Pulse Width 4 µs / 8 µs

– Long pulse mode for FEL– 2 modes changeable by remote control.

• Flatness of the flat top < 0.2 % (< 0.1 %)• Pulse-to-pulse fluctuations< 0.1 % (< 0.05 %)• Repetition

– 60 pps for the short pulse mode– 30 pps for the long pulse mode

• Inverter type HV generator– Stable and efficient

• Thyratron Switch– To be replaced with SSD

• Remote control using FL-net.

Pulse Modulator for Klystron 6

Master Oscillator 7

Doors, Radiation Monitors,Instruments

RF-Amplif ier-PSKlystron Modulator

108MHzMaster Oscillator

Subharmonic Buncher1~3 Controllers

Helmholtz Coil-PS-PB,B,A1,A2

Steering Coil (FEL)-PS-F5~8

Electron Gun

(EG)

Bending Magnet-PS-A1

Faraday Cup

Steering Coil 2-PS-1~8

Quadrupole Magnet-PS-A1~4

Bending Magnet-PS-F1,2

Beam Slit for BunchCompression

Beam Shutter-1~3

Bending Magnet-PS-1

Video Switcher

Quadruple Magnet-PS-F1~5

Injection TriggerSystem

Gate Valve-1~6Analyzer Slit

Beam Profile Monitor-1~3Beam Profile Monitor-F1~5

Ion Pump-PS-1~9,A1, F1~3

Ion Gauge-PS1~3CCG-4,Dual-5

Gauss Meter

Ethernet

Gateway ServerOperator Terminal-PC

Safety SystemInterlock PLC

（including an emergencystop button and a key

switch）

Steering Coil 1-PS-1~8

QuadrupoleMagnet-PS-1~11

Helmholtz Coil-PS-S1~8

Bending Magnet-PS-2RS485

RS485

Interlock PC

PLC Pannel in the Control Room （CNT- DCS)

Linac Room PLC１Linac Room PLC3

（LNC1- DCS)(LNC2- DCS- 3)

Bending Magnet-PS-3

GPIB

RS232C

RS232C

RS485

Control Room PLC１Control Room PLC２

（CNT１- DCS）（CNT２- DCS）

FL- net

FL- net

Operation OK Signal

Vacu

um F

ault

H U B

H U B

Linac Room PLC２（LNC2- DCS- 1,2,3)

FL- netH U B

RS232C

Steering Coil (FEL)-PS-F1~4

RS485

RS485

PLC Pannel in the Linac Room （LNC- DCS)

RF-Buncher-Attenuator,PSRF-PreBuncher-Attenulator,PS

Electon Gun HV-PS

RS485

Computer control system 8

GUI of Computer control system

All parameters are automatically saved, so that they can be restored in the next operation.

9

2. S-band photocathod RF-gun linac

Prof. Y.Yoshida group:J.Yang

Prof. S.Tagawa group:T.Kozawa

10

ps laser fs LaserSynchlorize

Photocathod RF-gun AcceleratorMagnetic pulse compression

KLY

Photochathod RF-gun linac 11

Linac fs laser

ps laser

12

3. Pulse radiolysis

Prof. S.Tagawa group:S.Seki, T.Kozawa, K.Kobayashi, K.Okamoto, A.Saeki

Prof. Y.Yoshida group:

Prof. T.Majima group:M.Fujitsuka, N.Ichinose, S.Tojo, K.Kawai

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IRIRNIRNIRVisVisUVUV

psps nsns µµss msms

History of Pulse Radiolysis at Osaka Univ.

UV, Vis 1994NIR, 1995Low-temp, NIR, Vis, 1997IR, 1998UV, Vis, ns-ms, 2001

ns system ps system (stroboscopic)

Laser-linac synchronized, 1995Vis, 1998Pulse compression, 1998Jitter compensation, 1999Improvement of S/N ratio, 2001

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LINAC (L-band electron linear accelerator)28MeV 8nsc

BeamCharge

Beam Catcher

Lens

MonochromatorSi / InGaAs Detector

TemperatureControl Wavelength Range

２５０ｎｍ～２１００ｎ

Sample Cell

CryostatOxford Instruments

Optistat DN

Xe Pulse LampTransient Digitizer

SCD 1000

SignalLiq. Nitrogen

Trig.

Trig.

Sync. Circuit

Gun

ns pulse radiolysis 15

ns pulse radiolysis

in Visual Basic

16

(SCN)(SCN)22--..

00 200200Time (Time (µµsecsec))

∆∆AA

00 8282Time (Time (µµsecsec))

∆∆AA

00 4141Time (Time (µµsecsec))

∆∆AA

00 2020Time (Time (µµsecsec))

∆∆AA

00 88Time (Time (µµsecsec))

∆∆AA

00 44Time (Time (µµsecsec))

∆∆AA

00 22Time (Time (µµsecsec))

∆∆AA

ns pulse radiolysis

A kinetic trace in wide dynamic range can be measured on one pulse irradiation

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Highest time resolution 800 ± 50 fsMonitoring wavelength 790 nm

Stroboscopic pulse radiolysis 18

Streak Camera etc Oscilloscope etc

GPIB-ENET

GPIB-ENET

etc

HUBHUB

GPIB-ENET

GPIB-ENET

Stroboscopic pulse radiolysis

in Visual C++

19

Fluctuation which comes from mechanical vibration of laser cavity etc.

≒12 ns

I0 I

This difference causesdegradation of SN ratio

I0 I

Nearly same amplitude

Improvement of S/N ratio

D.M.Bartels et al., J.Phys.Chem. A, 104, 1686 (2001)

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0 10 20 30 40 500 20 40 60 80 100Time [ns]

Ampli

tude [

arb.

unit]

Time [ns]

I0 I

Electron beam

Improvement of S/N ratio 21

-0.01

0

0.01

0.02

0.03

0.04

0.05

-50 0 50 100 150 200 250 300 350

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

-50 0 50 100 150 200 250 300 350

Opt

ical

den

sity

Time [ps]Time [ps]

Opt

ical

den

sity

Improvement of S/N ratio

Before improvement After improvement

T.Kozawa et al., Jpn. J. Appl. Phys., 41, 4208 (2002)

22

Fluctuation of Beam Position

-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0 500 1000 1500 2000 2500 3000 3500

測定回

BPM

(mm

)

Laser pulse

Electron beam

Cherenkov radiation

Sample

To Streak camera

To Si Photo detector

BPM Current detector

Laser pulse

Electron beam

Cherenkov radiation

Sample

To Streak camera

To Si Photo detector

BPM Current detector

0

10

20

30

40

50

-0.60 -0.40 -0.20 0.00 0.20 0.40 0.60ビーム位置変動 (m m )

カウ

ント数

Deviation of beam position (mm)

Num

ber

Measurement numberBeam position calculated by pickup voltage and a1=8.52 Deviation of beam position and Gauss fitting

Diagram of BPM calibration experiment

σ=0.18 mm

23

Calc. about effect of beam position on O.D.

{ }),(exp),(),(_

0),(,0),(,0

_

0),(,0),(,0nnB

nummesh

yxfyxfnnnL

nummesh

yxfyxfnnnL

i yxgyxgyxgInnBnnlnnBnnl

α−×+= ∑∑≤≤=>≤=

∑≤=

=nummesh

yxfnnnL

i

nnl

yxgI_

0),(,00 ),(

=),( nnL yxg

+− 2

22

2exp

21

L

nn

L

yxσπσ

（Gauss Function）

=),( nnB yxg

−+−− 2

22

2)()(

exp2

1

B

nin

B

hydxσπσ

i

i

i II

DensityOptical 0log][ =

（Gauss Function）

<Algorism of BPM calibration>

24

-4 -2 0 2 4 6 8

LaserBeam

Calculation result of BPMRe

lative

valu

e of O

.D.

d v.s. Relative value of O.D. parameter1, parameter2

0.0

0.2

0.4

0.6

0.8

1.0

0.0 1.0 2.0 3.0 4.0

σ L (mm) σ B (mm) h (mm) σ L boundarycondition

σ B boundarycondition

Parameter1 1.5 1.5 0.0 radius 1.5 mm radius 3σ mmParameter2 1.5 3.0 0.0 radius 1.5 mm radius 3σ mm

Simulation parameter

d [mm]

Relat

ive am

plitu

ded

Hole on cell holder

Image of position correlation between laser and beam

Almost no effect!

d (=separation between centers of each circle) [mm]

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Additional Summary 27

L-band linac was renewed and the renewal was completed in May 2004.

It will become a powerful tool for establishing bases of nanotechnology.

The nanosecond & picosecond pulse radiolysis have been developed.

The available wavelength of these system will expand and cover the range from UV to IR.