INJECTION AND EXTRACTION SYSTEM FOR THE 1ST RING CYCLOTRON
T. Itahashi, M. Inoue, A. Shimizu and I. Miura
Research Center for Nuclear Physics, Osaka University
Ibaraki, Osaka 567, JAPANAbstract
The injection and extraction system of the 1st ring cyclotron areredesined. The injection system is composed of two bending magnets, twomagnetic inflection channels, two quadrupole magnets and an electrostatic
inflection channel. The extraction system is composed of two electrostatic
extraction channels, two magnetic extraction channels and a bending magnet.
Optimal configuration s for some of these element have been determined byusing the TRIM code.
1. Introduction
An intermediate energy particle accelerator complex is being designed as
accelerator facility at RCNP. It consists of an injector cyclotron andnewa
two separated sector cyclotrons. Beam injection from the injector into the
1st separated sector cyclotron should be designed to meet necessities ofvariable energy and variable particles. The injection system has been
proposed to meet the optical properties from the point outside the sse to the
1st equilibrium orbit. Some preliminary studies for the extraction system
has been also designed.

2. Injection system
The injection system is designed to fit the high radial focussing frequencies vr~l.5. The injection trajectory for accelerated equilibrium orbit
and injection elements in the central region of the 1st ring are· shown inFig. 1. The characteristic s of the injection elements are given in Table 1.
The radial dispersion matching on the 'point to point' and 'parallel toparallel' transfer mode was studied using the computer code TRANSPORT. The
beam envelope and the trajectories for the point and parallel beams are shownin Fig. 2. A beam having an emittance, 12 mmx2.8 mrad in horizontal direction and 12 mmxl.4 mrad in vertical direction, is transfered to the injection
point as a beam just match the eigen-elipses , 4.8 mmx7 mrad and 4.2 mmx4 mradin horizontal and vertical directions respectively. The turn separation of
the beams on the injection point is 20 mm. The momentum acceptance of theinjection system is more than ±0.5%.
The MICl should raise the field inside the channel by about 3.3 KGaussat the maximum excitation of the sector magnet. A combination of the ironshims and 4 turns septum coils is confirmed to be fitted for economical andtechnical conditions by using the computer code TRIM. A 6 mm thick and 8 em
wide floating iron shims shown in Fig. 3 was chosen. The field inside theMICl can be varied about 10% of its maximum by changing the coils currents.
The flatness of the field inside the MICl at various excitation levels of thesector magnet was also confirmed by the combination of the coils currents.
The field distribution in the symmetry plane was shown in Fig. 3.
3. Extraction system
The extraction system is composed of two electrostatic extraction channels (EECl, EEC2), two magnetic extraction channels (MECl, MEC2) and abending magnet (BM3). The characteristi cs of the extraction elements aregiven in Table 1. At the extraction point in the valley, the turn separationof the beam is only 5 mm. However, the radial focussing frequencies of the1st ring is very high (vr~l.5) on the extraction radius for protons and lightions. Thus the turn separation of 10 mm can be achieved with proper precessional motion of the beam. The MECl is septum coil and the MEC2 has
dipole and quadrupole coils. The dipole coils are made of copper hollow-103-conductor. The
quadrupole coils arecooled by the dipolecoils through He gas
filled in the channel.
The MEC 1 may be
septum magnet composedof 4 turns coils.
The field inside theMECl was calculated
by using TRIM as shownin Fig. 4It needs
a little more rnodification by a furtherstudy.

Table 1
Chacactertstttcs ot the injeCt lOll a11d extcdctton elements

BM 1BM 2MIClMIC2
Ol02
EIC0I

length29"
10"

Hem( 10")87cm( 110")
78cm(94")
80cm(87")
lScm
lOcm
JOcm(J")

g•

30°

EECl
EEC2MECl
MEC2BM 3e,Max .•o•effective width
Vert.
Horiz.

llkG
l7.SkG(l6+3.3)kG(l6+0.9)kG
lkG/cm
0.2kG/cm
7SkV/cm

-21"
16.8.
22°

50cm(0.2")80cm(0.8")75cm
60cm(4.5°)l07cm(45")

field

60kV/cm
75kV/cm( 16-0. 5) kG
JkG+O. SkG/cm
l6kG

Scm
Scm
J.Scm
J.Scm
Scm
4cm
l. Scm

J.Scm
J.Scm
4cm
4cm
Scm
2.Scm
2cm

l.Jcm

2cm
2cm
4cm
2cm
4cm

l. Scm

2cmJcm6cmt_____ju unr--:-1SmnI

Fig. 1. Layout of the injection andextraction system for the 1st ring.

nFig. 2. Beam envelope of injectedbeam into the 1st ring.

tl'.OKC"•••11•1411,0I)

O.IKG_,,-··...

"-....

/ /./.·"///././ /./L)(//LL/l?(Uf-J7j''; --·... __L·I~ l,_ ~~-'·-· _....,!.,.. ~"" '·-· --~---·---L•"'"MK< '" CM

Fig. 3. Calculated field distribution of
the magnetic inflection channel 1.

-104-..

"Fig. 4. Calculated field distribution around the MEC-1.