INJECTION SYSTEM OF H BEAM IN KEK BOOSTER SYNCHROTRON
Tadamichi KAWAKUBO, Hiroshi SASAKI, Izumi SAKAI and Masaaki SUETAKE
National Laboratory for High Energy Physics

Abstract
We have a plan of H- ion beam injection into KEK booster synchrotron .
After the acceleratio n by the pre-injecto r and the linac, the H- ion beam isconverted to proton beam with a carbon film stripper at the entrance of thebooster, and injected into the booster ring. The merit of this injection
scheme is to capture the linac beam of long duration in the booster.

Magnet and monitor arrangement
The arrangement of magnets
STRAIGHT SECTION I CHAMBER-------,and monitors for the injectionr-------BUMP I
scheme is shown in Fig.l. The
H- beam from the 20 MeV linac
is injected onto an injection
orbit, which is formed by distorting a portion of the central
orbit with bump magnets 1, 2, 3
and 4 as shown in Fig.l. The
H- beam is converted to a proton
Pr.lbeam by passing through a carbon
film stripper set on the injection
orbit. After one turn revoluFig.l H-ion beam injection system in KEKtion, the proton beam meetsbooster (arbitrary unit)
the H- beam. from the linac at
BUMP 1 ~ 4: Orbit bump magnet
Owing
the stripper position.
Septum magnet
SEPTUM:to the difference of the charge
Secondary emission type
Pr. 1 ~ 6:
topossible
states, it ismulti-wire profile monitor
occupy the same position in a
Carbon film
C.F.:
phase space by the proton andScraperSc.:
H- beam. As the proton beam
boostertheincirculating
passes through the carbon film repeatedly during the H- beam injection, its
betatron amplitude is increased by the scattering of carbon atoms and thedecreasing of its momentum. When this amplitude reaches the acceptance ofthe booster, the multi-turn injection of the H- beam is turned· off and themagnetic fields of all bump magnets fall off to zero rapidly. As the proton
beam begins to take betatron oscillation along the booster central orbit at
this time, it does not collide with the carbon film any longer and the increaseof the betatron amplitude ceases. In order to make fine tuning of the beamorbit, six profile monitors (Pr. 1 ~ 6) which are secondary emission typemulti-wire detector are installed in the line.
1.

Bump magnets and their power supply
As all bump magnets (BUMP 1 ~ 4) always have to be the same field, theyshould be constructed with same sizes and connected in series. The design
values of the bump magnet and its power supply are shown in Tables 1 and 2
respectivel y.
2.

-31-Bump

MagnetGap

Bump

DesignMagnet

(mm)

350

Peak

Currentheight(mm)

40

Flat

top

I Width(mm)160

Falling

LengthI

CoilTurn(f'H)

B(kG)

1.76
2.8(Tf )TimeTable 2.,
7 0I 0Design values of power
supply connected to bumpmagnet 1 'V 4 in series''''''\\I.."~0.5'''~'''

.1:

'\!
'!',, ___r-------

40

80

120
Turns

Estimation of beam intensitywith H injection scheme

8.9

1.0

Measurement and Simulation
Thin carbon films are on themarket and they are easily obtained. We inserted alternately
two carbon films with different
thickness into the central orbitof the present booster andmeasured the beam life. Theresults are quite in agreementwith the computer simulations.
(Fig.2)(}loS)

TIt (Design values of bumpmagnet 1 'V 4

Supply( KA)Time (T) ( f'S)

IL

Table 1Power(I)

Fig.2

160'"

200

Booster360
ring

Beam life with inserting carbon film
into central orbit of present booster

Using the same simulation
technique as above one, we
calculate the intensity of thebeam which is captured in the booster. The design values of the horizontal
and the vertical acceptance are (50 mm x 15 mr x TI) and (20 mm x 13 mr x rr)
respectively. But taking account of the closed orbit distortion, the values
are estimated to be (35 mm x 10 mr x rr) and (15 mm x 10 mr x rr) respectively.
We take some assumptions that the emittance of the H- ion beam from the linac
has a Gaussian density distribution whose twice standard deviation is 40 rrmm•
mr, and the intensity is 10 rnA. When such H- beam is injected to the booster
with a carbon film of 120 ~g/cm 2 thickness, the captured proton numbers per
pulse is expected to be 2.4 x 10 12 ppp. This value is about 4 times as muchas ~~e present one. with the. multi-tu~n injection scheme.
Reference1)
2)

C. Hojvat, et al. "The multiturn charge exchange injection system for theFermilab booster accelerator IEEE NS-26, No.3, p.3149, 1979.
K. R. Bourkland, 11 A 34 KA rapid cycling PFN power supply for driving injection magnets", IEEE NS-26, No.3, p.3974, 1979.

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