Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 48 (2015)

New fast-kicker system for Rare RI Ring
Y. Yamaguchi,∗1 H. Miura,∗1,∗2 Y. Abe,∗1,∗3 and M. Wakasugi∗1
We are developing a new fast-kicker system for Rare
RI Ring. Figure 1 shows the block diagram of the new
fast-kicker system. It primarily consists of a thyratron
Kicker magnet
12.5Ω
Charger
75kV

PFN 12.5Ω(adjustable)

Coaxial Cable
5m, 12.5Ω

Thyratronswitch
HV unitThyratron
Grid pulser

Coaxial Cable
15m, 12.5Ω

Dicharge trigger
for extraction(adjustable)
Control unitMatchingresistor
12.5Ω(adjusable)

Discharge trigger
for injection

Fig. 2. PFN charging waveform for injection/extraction.
Fig. 1. Block diagram of the new fast-kicker system.

∗1
∗2
∗3

RIKEN Nishina Center
Department of Physics, Saitama University
Institute of Physics, University of Tsukuba

We fabricated a prototype twin kicker magnet toinvestigate the magnetic field by using a single-turnlong search coil. Figure 3 shows the waveform of themagnetic field. Owing to the faster response time,Magnetic field [G]switch, a charger coupled with a pulse forming network(PFN), a kicker magnet, a matching resistor, and acontrol section of the discharge trigger. The thyratron
is a deuterium-filled three-gap ceramic CX1171, which
was assembled by e2v technologies. The kicker magnet
is a distributed constant type magnet with a characteristic impedance of 12.5 Ω. We use a new substrateof the thyratron grid pulser on the basis of a previous feasibility study1) to shorten the response time. In
addition, we adopt a fast-charger named the hybridcharging system2) to reduce the recharging time.
The new substrate of the thyratron grid pulser ismainly composed of four FET drivers, four MOSFETs, and four pulse transformers (PTs). Here, theresponse time refers to the interval between the timeof input of the discharge trigger signal and the time of
10 % of the thyratron current output. The responsetime steadies at around 250 ns when the charging voltage becomes 25 kV or more.
The hybrid charging system, which consists of amain charging part and a sub-charging part, is indispensable for extracting a particle from the ringin 700 µs using the same kicker magnet. The maincharge (90 %) is achieved in about 0.1 ms using adouble forward converter composed of IGBTs and aPT. After the main charging process is completed,the sub-charging process is immediately started. The
sub-charge is completed within 0.1 ms using a highfrequency (500 kHz) resonant circuit and a PT. In addition, a high-precision voltage divider, which connects
to the sub-part coupled with a comparator, can be
maintained at a constant charging voltage level within
the range of fluctuation of less than ± 1 %. Figure 2indicates an example of the PFN charging waveformfor injection/extraction.




465 ns







Triggerin          
Time [ns]

Fig. 3. Waveform of the magnetic field at the charging voltage Vc = 25 kV.

the propagation time from a trigger signal input tothe power supply until the flattop center of the kicker
magnetic field is about 465 ns. On the other hand,the shape of the flat-top part and the tail-part of thewaveform does not satisfy our requirements. The fluctuation of the flat-top, which is defined as ±80 ns ofthe flat-top center, should be maintained at less than±3%, and we want to restrict it to less than 0 ± 1%
for the region after 355 ns (for 200 MeV/u) from theflat-top center. Therefore, we are trying to reduce thedisturbance of the waveform.
References
1) Y. Yamaguchi et al.: RIKEN Accel. Prog. Rep. 44, 157(2011).
2) Y. Yamaguchi et al.: RIKEN Accel. Prog. Rep. 46, 166(2013).

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