OPERATION AND MAINTENANCE FOR JAERI AVF
CYCLOTRON SYSTEM
Y. Nakamura, T. Nara, T. Agematsu, I. Ishibori, S. Kurashima, M. Fukuda, S. Okumura,W. Yokota, K. Arakawa, N. Miyawaki, K. Yoshida and S. Tajima
Advanced Radiation Technology Center, JAERI
1233 Watanuki-cho, Takasaki-shi, Gunma, 370-1291, JAPAN
Abstract
Cyc lotron
HEC R
The AVF cyclotron system[1]-[3]Cyclotron(HYPERN ANOGAN)
VP
in TIARA facility has been smoothly
BU
Cyclotron
PC
Injection
operated since the first beamSL
systemsystem
Ion sourceBM
extraction in March 1991.
The
AM
SC
systemDQ
operation time for a year is about
DS
AM
Multi
IM
3200 hours on an average through
TQ
cusp
RS
HA1
GV
FCV
recent nine years.
LE1
BM
BM
AM
Especially, the cyclotron system is TP
BM
SQ ST
HX1
LA1
BS
HB1
needed the frequent alteration of
SM
AM:A nalyzing m agnet
BM
BM:B ending m agnet
ECR
BS
BS:Beam scan ner
operation condition according to(OCT OPUS) BU:Beam bunch er
LX1
DQ:Doublet qu adrupole magnet
many kinds of ion species required
DS:Beam d iag no stic station
LC0
FCV:Fast closing valve
HY1
GV:Gate valve
from the experimenters.
BM
IM:Inflection m agnet
L B1
HE2
PC:Pulsed typ e chopp er
AM
RS:Rotary beam shutter
In order to improve the beam
HE1
SC:Sine wave ch opper
BS
HD1
SL :Solen oid magnet
quality and quantity, we have carried L B2
SM :Switching magnet
HC1
SQ:Singlet quad rupole magn et
LD1
HZ1
TP:Target p or tout continuously so far many
TQ:Trip plet q uadrupole magnet
HD2
VP:Vacuum pu mp
Beamtransport
reconstruction and development.
systemFurthermore, now we are advancing
various countermeasure to form the
Figure 1 : The outline of whole cyclotron system.
micro beam of 1µm size by means ofseveral issues, such as the installation of a flat-top small one, also only makes proton and deuteron. Ion
acceleration system, reconstruction of the cyclotron centre beam goes into the horizontal injection line and isdeflected to upward direction. The ion beam is injected
region, and so on.
into the cyclotron from the bottom, then is extracted after
1 INTRODUCTION
acceleration. The most intense beam can be got at LA1
The TIARA (Takasaki Ion Accelerators for Advanced port (among 17 ports) in the light ion room 1. After the
Radiation Application), which has another meaning of the analyzing magnet, the ion beam is distributed up to sevenpapal triple crown in Roman Catholic, has been beam courses by the round switching magnet (SM).
For the convenience to the users, we can form single
introduced to promote mainly for materials science andbiotechnology at Takasaki branch office in JAERI (Japan pulse beam by the combination of sinusoidal and pulsed
Atomic Energy Research Institute). The building of the type chopper. Three beam scanners can provide uniform
irradiation area about 5-10 cm square within 10 % by
TIARA facility was completed on Dec, 1990.
The TIARA facility is equipped with four ion means of X-Y double scanning by triangular wave.
beam attenuators, which have theaccelerators. The largest one is 930S AVF cyclotron Furthermore, the -10, are installed in the injection line.
reduction
rate
of
10
which was fabricated by SHI (Sumitomo Heavy
Figure2isaphotographof 930S cyclotron just afterIndustries, Co. Ltd). One of three electrostatictheinstallation.
This
has
the
K-value of 110, harmonic
accelerators is a tandem accelerator with terminal voltageof 3 MV, the others are a 3 MV single-ended accelerator numbers of 1, 2 and 3 are available. The range of RF
and a 400 kV ion implanter for low and medium energy frequency is covered 10.6 to 22.0 MHz. The maximum
within our facility. We can deliver various ion species to magnetic field is 1.67 T at extraction radius when thethe users with a wide range of energy from 20 keV to main coil current is flowed at 900 A.
about 1 GeV.
3 OPERATION AND MAINTENANCE

2 CYCLOTRON SYSTEM
Figure 1 shows the outline of the cyclotron system.
We have three ion sources, both of “Hypernanogan” and“Octopus” are ECR types, usually generate heavy ionsheavier than helium. A multi cusp has a hot filament, isFirst beam of helium 2+, 50 MeV was successfully
extracted on late Mar in 1991. After the acceptance test,
training and tuning were continued for about 9 months,
actual operation for research experiment was begun on
the trial base on Jan, 1992.

once because of poor vacuum of the cyclotron.

3.2 Operation and Utilization

Vacuum : 1.5 × 10-5 Pa
2-3 mmShield case~ 5 mm2 mm tInsideLeakage

OutsideMagnetic channel*IN

Most outer
beam
MID

OUT

Extraction
beam

3 mm tEntrance baffle slit

Atom osphere

Figure 4 : Vacuum leakage at magnetic channel.
For recent 7 years, an allotted beam time almost does
not change, while the time for beam tuning rather
increases. The time for beam tuning occupied by the fieldof biotechnology becomes to be large rapidly. The ratio
of its occupation already reached 54 % of the whole timeat the end of last fiscal year.
Figure 6 shows the frequency of the change ofharmonic number, particle, energy and beam course.
These frequencies increase year by year, especially thechange of beam course attains to about 300 times. We

3216

3203

3132

3271

2000

Cocktail
3286

2500

Xe
Metal
3070

3000

Ar
Kr

3233

3500

O
Ne
3068

He
C
3247

H
D

2464

So far, we experienced a lot of various troubles for 12
years. A few of typical serious troubles are shown below.
On Jun in 94, the rotating vanes in the TMP, as shown in
Fig. 3, were broken to thousand pieces surrounding thebeam line. This 600 L/s TMP was put at the beamtransport line upstream the HD1 port. We could not know
the cause of this breakdown although the inspection ofresidual vane pieces was carefully investigated by the
special metal company. The removal of broken pieces
around the SM and along the trunk line was need.
Luckily, in the cyclotron, we could not discover any
pieces from this TMP.
On Sep in 96, an inflector stem was fallen during theworking for harmonic change, because of insufficientinterlock sequence and careless operation. The weight ofthis stem was about 350 kg, and height of the dropping
was about 1.7 m. Several covers and dumping rubber
were wound by the falling impact, however fortunately
anyone suffered damage at all. After trouble, of course,
we exchanged broken and damaged parts, improved aninterlock sequence for the inflector change, also added on
the balancing weight behind the tower frame.
Next, on Nov in 01, the vacuum leak suddenly
happened when several µA intense beams of proton 70
MeV had been tuned. We confirmed that this vacuum
leak came from the meltdown of magnetic channel caseby beam bombardment, as illustrated in Fig. 4. The causeof this trouble was the reason why the position of baffleslit “IN” was not correct only about 3 mm.
Furthermore, water leakage in the vacuum chamber
occurred several times
so far. The most serious
leakage was generated
at the entrance ofmagnetic channel. The
amount of leakage
water was estimated atabout 50 litters. And,the contact fingers for
shorting plate in theresonator were melted
Figure 3 : Broken TMP.

00

01

Average : 3192 (h)1578

3.1 Serious troubles

Operation time (h)Figure 2 : General view of 930S cyclotron just after
installation

Some statistical data related to the operation andexperimental utilization for past years is explained
followings. The number of experimental subjects isalmost around 50 for past 11 years. However, subjects
for biotechnology greatly increase up to 35 from 9.
Operation time and accelerated particles are shown in
Fig. 5. Operation time has been kept more than 3000
hours certainly although we had a lot of various troubles
as mentioned just before. The numeric value of 3192
hours on the average for recent nine years is completely
the same as the sea level of second highest mountain in
Japan, its name is “Kita-dake” located in Southern Alps.
By the way, the quantity of proton is roughly same over
10 years, and the cocktail beam appears slightly in 95,
then gradually increases. Furthermore, a metallic ferric
ion was also delivered first in 99.

1500
1000
500
0

91

92

93

94

95

96

97

98

99

Fiscal year

Figure 5 : Statistics of the accelerated particles and theirbeam time for past 11 years.

300
Harmonic number
Particle
EnergyBeam course

Frequency

250

Perhaps, the busiest
cyclotron in the world !

200
150
100
50
0
92

93

94

95

96

97

98

99

00

01

02

Fiscal year

Figure 6 : Frequency of the change of harmonic number,particle, energy and beam course for past 11 years.
think without consulting anyone that our cyclotron is thebusiest cyclotron in the world. This is our catchphrase.
Furthermore, actual operation chart is very complicatedby the cascades of short-time utilization. We usually start
the beam delivery at 14 or 15 o’clock on Monday.
Generally, Start-up time including the harmonic change istaken four hours, and standard changing time for ion
species is three hours. The change of the beam course oruser is required one hour under same species. The
minimum allotted time is 30 min for individual user.
The operation chart is usually made so as to satisfy as
enough as possible various requests from the users. In an
example of last Feb, eleven hours are divided into nine
bio-users commonly. And the other user hopes to utilize
every Monday morning, another user requests to get twice
only one hour interval from 15 to 16 o’clock in 2
Wednesdays for one month.
As these circumferences, the efficiency of machinetime slowly lowers with the reduction of about 2 % for ayear. The efficiency is defined the ratio of time for beamtuning to allotted beam time. This condition is a little
serious problem for our experimental utilization.

3.3 Duty Condition and Schedule

exception of periodical maintenance and some inspection.
The utilization schedule for experiment consists of three
periods. First period is Apr to Aug, second Sep to Dec
and third Jan to Mar, respectively. According to theutilization schedule through Japanese fiscal year (JFY)2003, usable machine time for each period is 1302, 1290
and 874 hours in turn, total time through a year issummed up 3466 hours. Because the efficiency of themachine time has been predicted at 0.75 based on thepresent condition, the allotted beam time for users will be
estimated at just 2600 hours. As the reference data,
usable machine time was 3324 hours for JFY 2002.

3.4 Maintenance
We will stop the cyclotron system for four weeks foroverhaul and extra two weeks for beam tuning in summer
season during JFY 2003. And for two weeks in next
spring, the system will be stopped again for somereconstruction and maintenance.
Table 1 shows a periodical maintenance list every year,
two years or more for the devices and parts. We used to
do many kinds of maintenance and inspection fordifferent intervals according to the recommendatory
period and actual condition. Especially, we have paid
special attention for those devices which are classified
into the periodical interval more than three years. Of
course, we take care of the cyclotron every year.

4 DEVELOPMENT AND
IMPROVEMENT
A few examples of our activities connected with
development and improvement are described below. Oneof them is the development of cocktail beam[4]-[5]. An
example of cocktail beam M/Q=4 is illustrated in Fig. 7.
Single ion species can be extracted easily by the only
slight change of RF frequency after several cocktail ionswith M/Q=4 are injected into the cyclotron
simultaneously. As the users can get quickly desired ion
species every a few minutes, the efficiencies for theirexperiments were improved drastically.
Actually, a series of cocktail beam M/Q=5 is used

The cyclotron system is operated continuously during
one week from Monday morning to Friday evening.
Therefore, duty condition for
operators is determined based on
Table 1 : Periodical maintenance list for devices and parts.
this situation. Unit operation crew
Contents
Mk Remark ITVL
Contents
Mk Remarkof two persons changes their shifts ITVL
Cyclotron (Position, Insulation,
930S#
every 12 hours at 9:00 in the
Mechanical operation, RF system)
Power supplies (~30)
3#morning and 21:00 at night throughLubrication oil for rotary pumps ( ~ 50)%
Inflector electrodes (14)five weekdays. And, the other two# H=1,2,3
Power distributers for Insulating
Cooling fans (~320)% 34000 h# Regulat. 4 Batteries for sequencer (~ 20)
persons or four persons work for day
inspection (7)
% RAM
n, γ
Radiation monitors (~40 ch)
duty during 9:00 to 17:30.
1 Interlock sequence and indication (1 set) # Regulat.
Battery
setforuninterrupted
power#% Recomm.
Basically, the number of operators
Number of operations for principal
supplies (5)5#equipments(5)
is required eight at least. In actual,
Insulation and voltage check for ion#
pumps (32)
Synflex (Nylon) tube ⇒Rubber tube
Reliabi.
nine operators work for our&(Only principal part)
Leak detectors for harmful gas (1 set)#
cyclotron system, one of them
Synflex tube (Whole system)
Radiation dose at various positions (40) # n, γ
% Reliabi.
Control (push button) switches (~4000)
Safety (light weight) doors (5)#& Poorfunctions as a reserve in case of the
Cryogenic pumps (9)# Overhaul Once O-rings for flow meter in cooling system % Poor
occurrence of private business or
Sinusoidal chopper (1)Bellows for contact finger in RFresonator# 40 kV& Leakage(~50)
Beam scanners (3)# X-Ysudden illness.
2 Shielding (heavy weight) doors (7)#The cyclotron facility has been
Batteries for TMP (10)% Recomm.
also utilized through a year with the Notation, &:Renewal or Replacement, %:Exchange, #:Inspection, (n) : The number of instruments.

cyclotron system because the energy spreadis needed to restrict less than 200 ppm for the
AVF cyclotron
micro beam formation. Prior to the designing,
A series of M/Q=5,
Wide range search of LET and
wemeasured
severalimportantalready delivered
range : rapid improvement of
15 3+
experimental efficiency
characteristics for flat-top system by theN ,56 MeV20
Ne4+, 75 MeV
cooperation of Riken and Tohoku University.
f : RF frequency
Principle h : harmonic number
40 8+
Ar , 150 MeV
Q : charge state
In our flat-top system, fifth-harmonic RF
M : mass
84 17+
Simultaneous
Kr , 320 MeV
Proportion
B : Magnetic field
wave with the frequency range of 55 to 110
acceleration of
Quick change
M/Q=4 ions
MHz is superimposed on the fundamental RF.
A series of M/Q=4,
He , O , Ne , Ar , Ni , Krjust begun to deliverf
After the preliminary test and tuning, now we
Q
• B
=
2π •
4
He1+, 25 MeV
ECR ion sourceMhare sometimes operating the flat-top system
M/Q=4
16 4+
O , 100 MeV
Ri:Resolution of ion species
to improve the beam quality of 20Ne7+, 260
22
Generation of cocktail ions
Ne6+, 164 MeV
f(M Q ) =R=
MeV ion, which is one of the candidates of
10+
40 10
Isotope + Scaling∆ (M Q )Ar , 250 MeV∆ fions
methodmicro beam species.
58 15+
Ni , 390 MeV.
Typical resolution of cyclotron:Rc =. 3300
A series of M/Q=2 has been
82 20+In addition, we have also developed an
Kr , 490 MeV> Ri
Need !! Rc =not used to experiment yet.
operator assistance system for visual beamadjustment[9]. It is made sure that the
Figure 7 : An example of “Cocktail beam” with M/Q=4.
simulation of beam trajectory using thisfrequently. On the other hand, in case of M/Q=4, we add system faithfully reproduces the actual beam condition.
isotope ions on the original series because of the The simulation result of the beam envelope along the
reduction of impurity ions which are required less than longest beam transport line to the HZ1 port was obviously
100 ppm.
in accordance with the amount of the floor sinkage at
We had worried about serious beam decrease, trunk beam line just behind the cyclotron.
especially early operational condition and high magnetic
5 PRESENT STATUS
field. Therefore, operators had to adjust sometimes using
the most outer trimming coil. In order to investigate thisThe list of ion species accelerated by our cyclotron so
phenomenon, we measured various physical quantities
far is summarized in table 2. We have already developed
such as temperature, magnetic field by carefully designed
63 ion species. Ion species with harmonic number 2 are
NMR, displacement using a precise laser hologauge,
accelerated beam phase and transmission. And, thermal occupied up to 50 % of all. The highest energy ofanalysis dealt with three-dimensional model was also 36Ar18+ is 970 MeV which is close to 1 GeV. The best
carried out by SHI. Based on the comprehensive Tall, we usually call it “transmission”, is 31 % for D+, 25
consideration and measurement result[6], we concluded MeV.
Finally, we would like to show only two examples ofthat the cause of beam decrease originated into
research
activities. The research for the movement of“magnetizing factor effect”.
molecules
and ions in a plant has been carried out[10].
This effect is explained followings. If the medianplane space changes the shape or distance, it will affect The principle of positron annihilation is applied to thismagnetic field where revolving ions pass through. research. Sample plant is put at the centre between a pairof BGO-scintillator arrays.
The movement of
Actually, it is confirmed that the
An example of M/Q=4 ions

Impure ions are required
less than 100 ppm !!

Quick change : shortening
to a few minutes from ~ 2hours on normal change

RF

4

1+ 16

4+ 22

6 + 4010 + 58

15 + 82

20 +

RF

RF

whole body of the cyclotron expandsslightly because of the temperaturerise by heat transfer.
We performed the measures forstabilization of the cyclotron
beam[7]. Principal heat sources in
the cyclotron are main coil andtrimming coils as shown in Fig. 8.
We inserted the water jacket panel
between main coil stack and lower
yoke, and we reconstructed a new
exclusive cooling system, which isseparated from common coolingloop for twelve pairs of trimmingcoils. After reconstruction, the beam
condition became to be stable forvery long time more than 50 hours
without any tunings.
On last March, the flat-top
system[8] was added on the original

T rim m in g co il

Dee e le c t r o d eHH

Se c t o r

Sid e y ok e

H

Po le

260 0

RF

Main coil

Gap 7mm

Water jacket

Lower yoke
5 19 0: Hea t f lo w

H : Heat so u rce

Sectional view (1/4) and main heat sources

Impossible to improve because of narrow space

Outline of cyclotron and principal measures
Stabilization oftemperature andmagnetic field

1145

Insertion ofjacket23°C, 5 kW
Temp. control
for trim. coils

25°C, 30 kkWW
043

Appearance of water jacket (1/8 piece)Th
The
ermal ininssulationfrom coil stack

Restriction of heatflow from trim. coils

Room temp. control in vault

Stabilization ofbeam

Future subject
Optimum control method

Figure 8 : Measures for stabilization of cyclotron beam.

radioisotope-labelled material in the barley and soybean isinvestigated visually.
Another one is the research for ion-beam breeding ofplant.
Especially, heavy ion beams have superior
possibility for mutation induction in comparison with low
LET radiation such as gamma rays and electrons.
Recently, carnation flowers with new colour and shape
have been developed by ion beam irradiation incooperation with Kirin Brewery Co., Ltd. Those havebeen already commercialized as “Vital Ion Series”[11].
And, chrysanthemum flowers have been also studied bysame manner, we hear that they will be sold in the market
in near future.

6 SUMMARY
As mentioned before, we have realized the reliable
operation and maintenance for 12 years since 1991.
Simple our summary for these is shown in Fig. 9. The
operation and maintenance are always required thereliability and durability. And, the repair has to be done
as quickly as possible. On the other hand, development,
improvement and reconstruction should be continued tofurther progress the research activities in the future.
These issues including two groups function as the bothwheels of motive vehicle for the cyclotron system. Of
course, it is the precondition for success that the membersof our cyclotron group keep to have their zeal, aspirations,

7 REFERENCES[1] K. Arakawa, Y. Nakamura, et. al., JAERI-M 93-047.
pp 1-54 (1992)[2] Y. Nakamura, T. Nara, et al., Proc. 16 th Int. Conf.

Both wheels of
motive vehicle

Reliability

MaintenanceDurability

RepairCyclotron
systemOperation

As quickly as possible
Mutual dependence

Development

Futureprogress

Improvement
Reconstruction
Cyclotron
group

Zeal, Aspiration,
Responsibility etc.

Figure 9 : Simple summary for operation and maintenance.
responsibility and so on.

ACKNOWLEDGEMENT
The authors would like to greatly thank their devoted
efforts of nine operators who work for our cyclotron
system for day and night, especially.
We also wish to express our thanks to Dr. M. Saidoh
and Dr. Y. Ohara in our technology center for thecontinuous support and assistance.

Cyclo. Their Applic., East Lansing, MI, USA, pp 129132 (2001)[3] Y. Nakamura, T. Nara, et. al., JAERI-Review 2002-35.
pp 300-302 (2002)[4] W. Yokota, M. Fukuda, et. al., Proc. 12th Sympo.
Accel. Sci. Technol., Wako, Japan, pp 127-129 (1999)

Table 2 The List of ion species accelerated by JAERI AVF cyclotron so far.
Ion Energy Beam Text
species (MeV) (emA) (%)

H+

H+

D+
D+
He2+
4
He+

3

4

He2+

4

He2+

10
20
30
45
50
55
60
65
70
80
90
10
20
25
35
50
60
25
20
30
50
100

Tall
(%)
12
80
27
7
77
23
5
67
22
30
79
14
5
44
14
5
63
14
5
57
22
7
62
12
5
42
12
3
47
13
10
48
7.7
11
29
3.7
5.6
80
16
15
88
31
40
59
13
20
49
7.2
8.2
68
18
3.6 M/Q=4 13
5.5
69
12
10
42
10
20
62
22
10
32
10

Ion Energy Beamspecies (MeV) (emA)

Ion Energy Beamspecies (MeV) (emA)

4

36

He2+
C3+
12 5+
C
12 6+
C
14 3+
N
15 3+
N
16 4+
O
16 5+
O
16 6+
O
16 7+
O
16 7+
O
16 8+
O
20
Ne4+
20
Ne5+
20
Ne6+
20
Ne6+
20
Ne7+
20
Ne7+
20
Ne8+
20
Ne10+
22
Ne6+
36
Ar8+
12

108
75
220
320
67
56
100
100
160
225
335
430
75
125
120
200
260
270
350
540
165
195

Text
Tall
(%)
(%)
1.6 M/Q=2
2.0 M/Q=4
1.077
220 M/Q=24.0
43
100.70 M/Q=5 5.0
5.0 M/Q=4 22
4.0
34
21
1.9
58
21
1.0
82
13
0.1
41
6
0 M/Q=2
1.5 M/Q=5 6.6
0.01 M/Q=4
1.6
53
18
0.80 Scaling 10
3.0
70
19
0.28 Scaling 14
1.5
63
23
5
10 cps M/Q=2
0.007 M/Q=4
2.5
73
13

Ar10+
Ar18+

36

40

Ar8+

40

Ar10+
Ar11+
40
Ar13+
40
Ca9+
56
Fe11+
56
Fe15+
58
Ni15+
82
Kr20+
84
Kr17+
84
Kr18+
84
Kr20+
84
Kr21+
102
Ru18+
129
Xe23+
197
Au31+
40

195
970
150
175
250
330
460
200
210
400
390
490
320
400
520
525
320
450
500

Text
(%)
0.1
43
5
10 cps M/Q=2
2.4 M/Q=53.0
73
0.2 M/Q=4
0.7
86
0.03
63
2.0
61
1.4 M/Q=50.59
660.01 M/Q=4
6
10 cps M/Q=40.08 M/Q=5
0.04
60
0.06
72
0
M/Q=4
0.02
54
0.2
72
0.02
49

Tall
(%)
1.2
6.2
15
22
24
11
16
28

5.0
2
22
3
11
3

M/Q = 2, 4 and 5 : Cocktail beams

Color notation H=1 H=2
Total : 63 species

Text : ratio of the beam current at the Faraday cup just behind the cyclotron to that at 900 mm of the cyclotron radius.
Tall : ratio of the beam current extracted from the cyclotron to that injected into.

H=3

[5] I. Ishibori, M. Fukuda, et. al., Proc. 12th Sympo.
Accel. Sci. Technol., Wako, Japan, pp 453-455 (1999)[6] S. Okumura, K. Arakawa, et al., Proc. 16th Int. Conf.
Cyclo. Their Applic., East Lansing, MI, USA, pp 330332 (2001)[7] Y. Nakamura, S. Okumura, et. al., JAERI-Review
2000-24, pp 282-284 (2000)[8] S. Kurashima, M. Fukuda, et. al., Proc. 16th Int. Conf.
Cyclo. Their Applic., East Lansing, MI, USA, pp 303305 (2001)[9] T. Agematsu, K. Arakawa, et. al., this workshop[10] S. Matsuhashi, S. Watanabe, et. al., JAERI-Review
2002-35. pp 86-88 (2002)[11] M. Okamura, N. Yasuno, et. al., JAERI-Review
2002-35. pp 39-41 (2002)