MODEL STUDIES FOR THE MAGNETS OF THE RING CYCLOTRON PRCJECT IN RCNP
K. Hosono, K. Enoki and I. Miura
Research Center for Nuclear Physics, Osaka University, Suita, Osaka
An intermediat.e energy particle accelerator complex is being designed asa new accelerator facility of RCNP. The proposed facility 1 l consists of two
separated sector cyclotrons, an injector cyclotron as an injector for lightions and a Wideroe type variable frequency linac as an injector for heavy ions.
Magnetic field studies have been started for the lst and 2nd rings. A 1/3.5scale model magnet of the lst ring and a 1/4-scale model magnet of the 2nd
ring have been made to study various magnetic field properties. The magnetic
field characteristic of these models and the results of orbital analyses aredescribed.

Model Magnet of the lst Ring
A 1/3.5-scale model magnet of the lst ring has been prepared to study
various magnetic field properti·es. The model magnet weighs about 8-tons. The
radial pole edges are shaped stepwise into a Rogowski's curVe with a numerically controlled milling machine. The designed maxium flux density in yoke isabout 15 kG. The gap width is 22.9 mm.
A single F.W. Bell Hall probe have been used for magnetic field measure~ments. The mean temperature coefficient of the probe is quoted as ±so ppm/°C
Thus no attempt has been .made to regulate temperature of the probe, nor tocorrect the Hall voltage with the temperature coefficient. The Hall probe ismounted on an end of aluminum arm stretched from probe carriage~,3l.to thecenter line of the model magnet. Magnetic field mapping has been made. on acartesian grid. The mapping hardware is interfaced to a computer:for automatic measurements)) .
Figure 1 di13plays a typicaL map of the magnetic field at a excitationlevel of 100 A(LO kG). Orbital properties of the lst ring have been studied
using these measured fields. Figure 2 shows the calculated isochronous fields
for maximum energies of various ions as a full-scale radius. Figure 3 shows .
the radial and axial focusing frequencies calculated with fields isochr.onizedexcept in the region near injection and extraction. We will be fr1=.e of instabilities caused by the essential resonances. The required radial fieldgra~
dient for isochronism shown in fig. 2 will be produced by trim coils mounted
onto the pole faces. The trim coils for a 1/3.5-scale model magnet have been
designed and the fields are being measured. ·Model Magnet of the 2nd Ring
A 1/4-scale model magnet of the 2nd
ring has been also . prepared to study
various magnetic field properties. Planand side views of the model magnet,
weighing about 5-tons, is shown in fig ..
4. The radial pole edges are also
shaped into a Rogowski's curve. The
gap width is 20 mm. The measuringsystem of the magnetic fields is same asthat for the .1st. ring. ..
Figure 5 shows ~· typical map of themagnetic field at a excitation level of
100 aUO kGl . Figure 6 shows calculated
isochronous fields for various' ions asa full-scale radius. Figure 7 shows theradial and axial focusing frequencies
calculated with fields isochr01iiz'ed
except in the region near injection and

l=lOOA

Fig. 1. A three dimensional display of·. a magnetic field at a.excitation level of 100 A (lO,kG).

-185-extraction. We can obtain proton energy of 520 MeV with the magnet from thepreliminary results of calculations. A little correction of the spiral angleof the 2nd ring is necessary in order to obtain more energies than 520 MeVproton energy.
18.-----~----~~----~-----.

R!NG1

17
16

1.3

15-ti

1.2

1H+(193 MeV)

1.1

11300

0/,~{··~,

Isochronous Fi~

1.2

400

1.3

1.4

1.5

1.6

lJr

Fig. 2. Calculated isochronous fields
using measured magnetic fields forvarious ions.

Fig. 3. Calculated radial and axial
frequencies based on measured magnetic fields.

Fig. 4. Planand side viewsof the 1/4scale model
magnet of the2nd ring.

Fig. 5 •. Three dimensional. displayof a magnetic field at a excitationlevel of 100 A (lOkG)
1.6 614M..V_20Ne5•:r ··""-----Rl~·z---~~F~g.
6. Calculated·::~1•

jlisochronous fields
using measured mag1 netic fields of thesv.A.,5-5$
1~f~~~~s ~ing for various~

3~62)[~-~~~:'H~··~·.J =~ 11 ·.32 1<1-~/231
f'iioR(c;/r'sbo

j:·4/52Me-V-P.

,._.

_:.·;

·~~ ~~~~~'·' u ,_,~0o 'Rl NG 2·~.

,, ,, "j1..,Fig. 7. Calculated radial and axial
frequencies for 2nd ring based on
measured magnetic fields.

References
1) I. Miura et al., IEEE Tras. Nucl. Sci. NS-26, 2074(1979)
2) I. Miura et al., RCNP Annual Report (1978} p. 231.
3) K. Hosono et al., RCNP Annual Report (1978) p. 240.

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