Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Battery-operated compact ion source for beam transport test
T. M. Kojima,∗1 T. Sonoda,∗1 I. Katayama,∗1 M. Wada,∗2 and H. Ishiyama∗1
An ion source for a beam transport test at theSLOWRI beamline1) has been desgined and assembled.
The beamline was constructed to transport slow rareisotope (RI) ions extracted with an accelerating voltage
of a few tens of kilovolts from the PALIS apparatus2)or RF gas cell.3) PALIS and the gas cell are systems
used for catching, thermalizing, and accumulating RIs
produced at BigRIPS. At present, neither PALIS nor
the gas cell is completed, and no ion can be extracted.
Instead of those systems, an ion source is necessary toexamine ion transport at the SLOWRI beamline. However, there is no room for installing a usual ion sourceat the upstream end of the beamline, since PALIS has
been already installed at that place, i.e., the F2 chamber of the BigRIPS facility.
The newly designed ion source is used as a sideinserted-type device. It can be installed at any of theparticular CF114 ﬂanges for the beam-proﬁle monitoron the duct (see Fig. 1). The system consists of an ion
emitter part and extraction part. The former is biased
at an accelerating voltage of a few tens of kilovolts sothat it is isolated with a CF70 isolating nipple. A comercial thermal-ionization-type alkali ion emitter (HeatWave Labs, Model 101139 Cs+ )4) surrounded with a
50 mmϕ repeller electrode is mounted at the end of theisolated rod (see Fig. 2). The emitter, which contains aheater inside, has a cylindrical shape of 6.35 mmϕ and9.9-mm length, and its end side is coated with alkalicompounds. Note that the center hole of the repeller
is 10 mmϕ, which is slightly larger than the emitter, toavoid thermal contact. The position of the emitter isdesigned to be on the axis of the beamline duct. The
heater power of the emitter is supplied by a lithium-ion

Fig. 2. Photograph of the electrode arrangement of the ion
source. The coated alkali compounds of the ion emitterare seen at the center of the repeller.

battery (GlobalTech, GANGAN GT5)5) with an output
regulating circuit. The battery and circuit are housedin an acrylic box mounted on the top of the isolating
nipple; thus, they are isolated from the GND potential.
Therefore, it is easy to apply a high voltage bias to theion emitter part. The battery, when fully charged, canoperate the ion source for more than ten hours underusual conditions. The extraction part is assembled on
the CF114 ﬂange at the GND potential. It has two electrodes, i.e., an extractor with a 6 mmϕ aperture anda “collimator” with a replacable aperture plate. Onecan adjust the emittance of extracted ions by changng
the aperture size of the “collimator,” though the extracted intensity decreases as the emittance decreases.
A 4 mmϕ aperture is set currently.
The ion source was tested at a very short (40 cm)
region of the beamline, which includes only one 20-cmlong electrostatic quadrupole between the ion source
and a Faraday cup. With 10-kV acceleration and 6.8W heater power, the ion current extracted through the4 mmϕ “collimator” was about 1 nA on the Faraday cup
at 40 cm downstream when the electrostatic quadrupole
was optimized. The intensity is suﬃcient for our purpose. In addition, a higher intensity is expected witha higher power since the rated power of the heater is11.3 W.
With this ion source, the ion-transport properties ofthe beamline will be examined and adjusted.
References

Fig. 1. Left: The assembled ion source without the heatercontroller. Right: The heater controller set on the topof the CF70 isolating nipple.
∗1∗2

RIKEN Nishina Center
KEK Wako Nuclear Science Center

1) M. Wada et al., RIKEN Accel. Prog. Rep. 47, 203 (2014).
2) T. Sonoda et al., Prog. Theor. Exp. Phys. 2019, 113D02(2019).
3) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B
204, 570–581 (2003).
4) https://www.cathode.com/i_alkali.htm .
5) https://g-tech.jp/gt5 . (in Japanese)- 109 -