AUTOMATIC CONTROL OF GAS CIRCULATION AND GAS-FEED SYSTEMFOR ION SOURCE OF 160 CM CYCLOTRON
T. Noda, K. Ikegami, N. Kamiyama and I. Kohno
The Institute of Physical and Chemical Research
Hirosawa 2-1, Wako-shi, Saitama, Japan
ABSTRACTThe circulation system and the gas-feed system forthe ion source of RIKEN 160 em cyclotron were newly
developed. The circulat~on system is 1 ~sed to rl~se thehigh cost gases such as He, enriched co 2 ando2 •The gas-feed system is used to feed eight kinds of gas.
The system has two gas-feed lines for making gas mix
with two gas flow controllers;·
These system can beoperated automatically according to the sequence predetermined by a programmable controller which is made of
OMRON SYSMAC M5R having I/O port of max 256 points.
CIRCULATION SYSTEM
313 co18The high cost gases such as He, enriched
2ando2 necessitate the use of a circulation system torecover any gas not accelerated or trapped in the cyclotron and to provide its purification for re-use in theion source.
Figure 1 shows a block diagram of the gas
circulation and the gas-feed system for the ion sourceof the cyclotron.
The system consists of a vacuumtight intake and exhaust rotary pump, first charcoal
trap, second two 3 charcoal traps TZ and T3, two reservoirs(one is fSr the Hr 8gas and another is for other gases
such asco 2 and o2), several pirani and absolute
PG2gauges, a rotary pump for evacuating, many air operated
and electromagnetic valves, and a programmable control~ler.
The syste~)is connected to the ion source in thecyclotron through a pressure controller.
Two mechanical booster pumps are connected to the circulation system
as main backing from the exhaust of diffusion pumps
without evacuating by the backing rotary pump.
Thegases produced in the chamber are passed through firstand second traps by the circulation pump.
The first
charcoal trap is cooled down below a temperature of -20
C by four thermoelectric cooling units.
Almost water
vapour of main component in the residual gases aretrapped in this charcoal.
Second trap is cooled down
~y liquid nitrogen.
The other residual gases except
He gas are adsorbed in the second trap.
The system can be automatically operated by one
touching with a programmable controller when we selectthe reservoir and traps..
The system is first evacuatedand the traps selected are cooled down.
After cooling
down the traps, the gas is supplied from the reservoir
in the system by the circulation pump and circulated topurify through traps in the system.
After purification,
the gas is sent through pressure controller to the ion
PG3

PGl
BAV3

MB2MBJ.

GEV19CYCLOTRON63

VACUUMCHAMBERION SOURCE

RPl and MRP: rotary pump.
RP2: circulation pump ( vacuum-tight intake and exhau,s t rotary pump) •MB: mechanical booster pump.
DP: diffusion pumps of 32 and 14 inch connected in series.
BAV, GAV, AV and S3: air operated valve.
V: hand valve.
GEV: electromagnetic valve.
Rl ~ R4: reservoir( Rl and R2: a volume of 15 t, R3 and R4: a volume of 100 mt ).
Tl: thermoelectric cooled charcoal trap.
T2 and T3: liquid nitrogen cooled charcoal trap with baking heater wound.
This trap is set in the thermos withthe lifter moved by a motor.
PR: pressure regulator.
PG and BG: pirani and ~bosolute gauge.
PC: pressure controller( 10-1 ~ 10 2 Torr ).
GFC: gas flow controller( GFCl: max 5 cc/min, GFCZ: max 10 cc/min).
Fig. 1 A block diagram of the circulation and the gas-feed system for the ion source of the 160 em cyclotron.
36source and recovered from the cyclotron to the system.
When the experiment is finished, the gas used is recovered into the reservoir by the circulation pump after
To remove the gases adsorbed in the traps,purification.
Go~the traps are evacuated by rotary pump while heating,-Ion Source--~

GAS-FEED SYSTEM
This system consists of eight kinds of gas bottle
having a pressure regulator, respectively, several air
operated and electromagnetic valves, and two gas-feedlines for making gas mix with a gas flow controller.
A gas flow controller is composed of a piezoelectric
Figure 2 shows avalve PV-10 and a mass flow meter.
The valve
block diagram of the gas flow controller.
PV-10 is operated by an electric pulse with a repetition
By varrate of 100 Hz and an amplitude of 40 ~ 100 V.
ying the pulse duration from 0 to 50 %, one gas flowcontroller(GFCl) can be controlled over a range of 0 to
5 cc/min and the other controller(GFC2) from 0 to 10
Figure 3 shows a gas flow rate for nitrogencc/min.
gas versus duty factor of the electric pulse applied to
the PV-10.
2)
In the case of mixed gas , the main gas issupplied to the ion source through one gas-feed line andthe supporting gas is supplied through the other line to
produce highly charged heavy ions and to operate stably
the ion source in the long time.
The system can be operated by one touching after
When the switch " START "the gas required is selected.
is pushed on the graphic panel, the system is evacuatedand gas is fed to the ion source.
At present, a gas flow rate is manually controlled
However, as the device has theon the control desk.
interface to control by a micro conputor, it will becontrolled by the microcomputor in the future.

~JUL~

_.j

10 mSEC

Cyclotron RoomControl Room
cc/mln

GFCl

0~5

GFC2

0-10 cc/mln

Fig. 2A block diagram of the gas flow controller.

50

10Repetition: 100Hz
Base Voltage: 44.6 V~z::E:......
u840~..

UJ1-Gas Flow
6304'20 .....
0~

3:0_J

REFERENCES..

l.Lu<I)

1) M. Tonuma, S. Nakajima, and K. Kohno., J. Vac. Soc.
Japan, Vol. 10, p22, (1967).
2) K. Ikegami, K. Ogiwara, T. Kageyama and I. Kohno.,
Proc. 6th on Ion Source and Ion-Assisted Tee. pl55,(1982).

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102.....
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002

4

6810

Dial Number of Controller
Fig. 337

Gas flow rate for :nttrogen gas versus dutyfactor of the electric pulse applied to thePV-10.