The 11th Symposium on Accelerator Science and Technology, Harima Science Garden City, 1997

Installation and measurement of the ATF Injection Kicker
T. Naito, T.Korhonen, K. Kubo, N. Terunuma, J.Urakawa,
A.R.Donaldson*, D.S.Williams*, P.Blum*, B.McKee*,KEK,High Energy Accelerator Organization, 1-1 Oho Tsukuba, lbaraki, Japan 305*Stanford Linear Accelerator Center, Stanford, CA 94309, USA
Abstract
An injection kicker system of the same type as SLC
North Damping Ring(NDR, for e- injection) is used at
ATF DR for future linear collider development in KEK.
The magnet and the power supply have been constructed
at SLAC and installed to the ATF DR at June 1996. The
operated from the beginning ofsystem has beencommissioning, January 1997, to the present operation,
July 1997, with single bunch injection mode. The
construction and the operation has been done as a part ofthe collaboration program of the ATF project. The
operation characteristics of the injection kicker were
measured using beam. The system configuration and theresult are described in this paper.

1 INTRODUCTION
ATF DR in KEK aims to make a small emittancebeam to obtain a high luminosity for future linear
collider. ATF was designed to circulate · multi-bunch
beam, 20 bunc:Q.es with 2.8ns spacing, and multi-train ofmax. 5 trains 1). The injection kicker magnet is required toproduce a pulse magnetic field which has very fast riseand fall time with 60ns flattop. The parameters shown in
Table 1, are almost the same as SLC NDR of SLAC. We
agreed to use the same type of the kicker system as a partof the collaboration program. The SLAC kicker system
has a long improvement history 2)3)4). Especially, theyspent large effort for the magnet to improve the pulse
shape and the higher voltage capability5). Thus thesystem is expected to have high reliability and good
pulse characteristics for ATF application.
The components of the kicker system weremanufactured and tested at SLAC. The system wasassembled and installed into ATF DR at June 1996. The
pulse characteristics were measured and confirmed theperformance except for the pulse flatness. The system
has been working from the commissioning to the present
without serious problem. The operation parameters were;energy: 0.95GeV(Jan-April) and 1.3GeV(May-July),
Intensity: 3-6xl09(single bunch), repetition rate:0.8 or
1.5 Hz. The operation characteristics of the kicker were
measured by using the beam.
SLC NDR
ATFDR
1.2GeV
1.5GeVEnergy
8mrad
5mrad
Kick angle
45cm
45cm
magnet length
710Gauss
510Gauss
fieldmagnetic
60ns
60ns
rise time
60ns
60ns
fall time
60ns
60ns
flat top
Table 1 Specification of the ATF/SLC injection kicker

2 SYSTEM DESCRIPTION AND
INSTALLATION CHARACTERIST ICSPFL Voltage: I th50kV:

MINERAL OIL (e"' 2.5) FILLED ALUMINUM TANK; tL._j_j_ :II! 100J.<S

045t-~8:,'------------·

14Junelle, DONALDSON& WIU.lAMS

Fig.l Simplified Schematic drawing of the kicker syste~

The schematic drawing of the kicker pulser is shownin Fig.l and the installed kicker magnet is shown inFig.2. The high voltage charges to two shorted pulse
forming lines. The charging starts about lOOJ.LSec before
the thyratrons are discharged. It is called command
charging and can hold the stable charging voltage for
Two thyratrons(CX1671D)
different repetition rate.
discharge at the same timing and the current is transferredto 12.5 ohm load termination through the kicker magnet.
The magnet is required to have a matched impedance forhigh frequency region. The specifications are; charging
voltage(max.): 80kV(the high voltage at the magnet
correspond to the half of the charging voltage),current(max.): 3200A(produce 948 Gauss at the magnet),
pulse width: 130ns(FWHM) and impedance: 12.5 ohm.

-267-The lith Symposium on Accelerator Science and Technology, Harima Science Garden City, 1997

ohm. The reflection rate was agreed with the impedancemismatch. However, the DC resistances were measured as
12.7 ohm and 12.2 ohm, respectively. Fig. 4 shows dB/dt
pick up coil signal which is proportional to the time
derivative of the magnet field. The amplitude jitter of thecharger voltage was 0.33%(peak to peak) which waslimited by the resolution of the instrumentation.
3Fl.g. 2 Installed kicker magnet at ATF
The kicker system was successfully installed andconnected to the trigger and control system. The magnet
was mounted on its own support and the beam line
chamber was pumped down to 5xl0-8 Torr. The magnet
was processed ,by watching the vacuum level, up to 48kV
charging voltage and at the repetition rate of 1Hz, 25Hz,
50Hz and 60Hz. There were no signs of arcing or the odorof ozone. The pulse characteristics were measured afterthe processing. Fig. 3 shows the wave shape of thecurrent of the two thyratrons. About 10% of reflection
was observed. The reflection is affected to the multi-train
injection. The spacing of the trains at the case of 5 train
is only 39.2ns. The calculated impedance from thevoltage wave shape and the current wave shape was 13.7
1200
1000~ BOOE
1:600"'"0e 400["'1-KICK ANGLE MEASUREMENTWITH BEAM

The kick angle of the beam was measured from theinjection orbit and the first turn orbit by changing thehigh voltage, the timing and the repetition rate. Thismeasurement was affected by the orbit error and the beamloss come from the small physical apertureof the baem
path. The estimation was done by #22BPM signal
located at 1.076m downstream of the kicker and the R12
and the R34 transfer matrices. The resolution of the BPM
was -1 OOj..Lm. The measurement was done with following
two conditions, the energy: 0.95GeV and 1.3GeV.
3.1 High voltage characteristics

The absolute kick angle couldn't be measured
directly, because the orbit couldn't be measured at zerovoltage setting. The differences of the kick angles at thedifferent high voltage settings from 16kV to 27kV weremeasured. The absolute kick angle was estimated bysubtracting the offset of the zero cross of the linear
fitting. Fig.5 shows high voltage characteristics at
0.95GeV. The obtained coefficients of horizontal kickwere -0.1409 micro-rad/V(0.95GeV) and -0.1179 microrad/V(l.3GeV). The results of the coefficients inhorizontal are about 10% deviated from the energy scale
factor. The kick angle at usual operation was measured as
3.lmrad(0.95GeV) and 3.4mrad(1.3GeV), respectively.
For vertical direction, a small kick angle was observed.

200

HV v.s. kick angle

01000 ..-~--.-.~.:::.::::::,•.-~-o~.o~q.-:c4:/::-r3;:-'+~-,c:·""o.•'.;xh"'"7o g:C:-a~66:::19:rr-~"! 500·-200-1 10'7 -5 10-8

05 10-8:

1 10' 7 1.5 10'7 2 10'7 2.510'7 310'7---~ ·347.64~+ 14.603X ~= 0.61807 ~=Time [sec]Fig.3 pulse shape of the thyratron currents

I.,"": •••••••••t•··••J10t~al""0~.."

0:12-5

....
i:75
al:

400f!

""~

350

300-4000

250
0-100

1 10'7

2 10'7

Time [sec]

1015

20

25

HV(kV)

3 HJ'

Fig. 5 High voltage characteristics

Fig.4 pulse shape of the dB/dt pick up-268-;;"'"'f!.:.

~::: •••••i••t::,i::•••::~~~l~5'?

:€II••~-;:t··~·~c•••f(fH~hfj

450

30~

i::-:..-

The 11th Symposium on Accelerator Science and Technology, Harima Science Garden City, 1997

micro-rad was 67.2ns for 0.95GeV and 1.3GeV. This isenough wide for ATF 20 bunch injection. The kick angle
at usual operation of the single bunch injection wasmeasured as 0 nsec point. This timing is near the centerof the flattop.

Timing v.s.KickAngle
550j

3000···········-···················

1: . •. •. . . ~ ;J :r::~~450··········-~-t~············=': ··I: t J:
15000................

:500400
350~1::1"'~-?"
300E250:........•...•.••.•. ; ........... .
-~-angle

200

3.3 Repetition rate characteristics

The repetition of beam trigger can be selected 0.8, 1.5,3.1, · 6.2, 12.5 and 25Hz. The dependence of the kickangle on the repetition rate is plotted in Fig.7. There isno clear difference at each repetition except for 0.8Hz.
The deviation at 0.8Hz comes from the operation
condition of the thyratrons. The thyratrons are not enoughstabilized at the low repetition rate.

-500 L......o._,_................L_._..........~......_~_,_~'---'--'-................J 150
50100-100·50
0Timing(ns)4Fig. 6 Timing characteristics
The coefficients were 0.0146 micro-rad/V(0.95GeV) and-0.0462 micro-rad/V(l.3 GeV). The vertical kick angle
was 10% and -40% of the horizontal kick angle. These
results of the vertical kick was included the effect of thebeam loss, the intensity was decreased at the low settings
in Fig.5.

3.2 Timing characteristics

The effective kick angle at the time domain can bemeasured by changing the beam injection timing andmeasuring the kick angle of the beam. The beam
injection timing at the kicker can be changed in 2.8ns
step by a programmable delay module. The absolute
kick angle couldn't be measured, because the orbit
couldn't be measured at the off timing of the flattop ofthe pulse. The differences of the kick angles at thedifferent injection timing settings near the flattop weremeasured.
Fig.6 shows the mJection timing
characteristics at 0.95GeV. The flattop width within 200

Rep.rate v.s. Kick angle
600

400

~. ~. ..l.~. . . . .l. . .~. . .L.. . . . .
i~e-~200'ir"'>-.~

0><·200ii.t1. . . . .

L. .........

iPti+ i.f. J..... i . r··+It If J.-1-1T. . . ..
...........f.............f......:..... J............. J...........

!

!

!

!

350;300

g.,..i.

SUMMARY

The injection kicker same type of the SLC NDR
was installed and the characteristics were measured ·byusing the beam. The kick angle at usual operation was3.1mrad (0.95GeV) and 3.4mrad(l.3GeV), respectively.
The design value is 5mrad. This deviation means that theinjection orbit at the septum region goes off-center andthere is a one of the reason of the beam loss. The pulse
shape of the magnetic field has 67 .2ns of the flattop
region which is adequate for multi-bunch injection. At
the case of the multi-bunch injection of 20 bunch, theflattop is required to 53.2ns.

5 ACKNOWLEDGMENTS
We would like to express our thanks to Professor
K.Takata for his encouragement. We also wish to thankATF operation group for their support.
REFERENCES[1] Ed. by F.Hinode, et al., "ATF Design Study Report••,KEK Internal 95-4, June 1995
[2] T.Mattison, et al.,"Status of the SLC Damping Ring
Kicker Systems", Proc. of IEEE Particle Ace. conf.
1991 pp2331-2333[3] T.Mattison, et al.,"Operational experience with SLC
Damping Ring Kicker Magnets", Proc. of IEEE
Particle Ace. conf. 1991 pp2955-2957[4] A.R. Donaldson et al., "Kicker thyratron Experiencefrom SLC", Proc. of IEEE Particle Ace. conf. 1991
pp3165-3167[5] T.Mattison, et al.,"Fast.and Reliable Kicker magnets
for the SLC Damping Rings", Proc. of IEEE Particle
Ace. conf. 1995 pp1915-1917

1"'.E.

250

200!

·400 .__._~......._....................~...................~..............................................., 150
152025.30
010
Repetition rate(Hz)Fig. 7 Repetition rate characteristics-269-