The 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

HV TRAPEZOID 1 f.IS-PULSE SWITCHING USING SI-THYRISTORFOR KICKER MAGNET SYSTEMS
Eiji NAKAMURA, Hikaru SATO, Mituso AKEMOTO, Tdamichi KA WAKUBO, Shigeru MURASUGI,High Energy Accelerator Organization (KEK), 1-1 Oho, Tsukuba, Ibaragi, Japan
Naohiro SIDMIZU,NGK INSULATORS, LID., 2-56 Suda-cho, Mizuho, Nagoya, Japan
Kenichi AOKI, Kazuya YOKOYAMA,
Sumitomo Heavy Industries, Ltd., 2-1-1 Yato, Tanashi, Tokyo, Japan

Abstract
The R&D on the fast rise/fall switching of highvoltage and large current trapezoid wave has been started
for the power supplies of kicker magnet using SIthyristors instead of thyratrons. Test experiment wasdemonstrated using the prototype SI-thyristor pulse
module, which is made for the klystron driver, connectedto the pulse forming line (PfL) with an end-clipper. Risetime of 0.3 JlS was observed for - 27 kV . It is possible tointroduce the SI-thyristors into the kicker system for alarge lepton accelerator ring at least. It is expected to
improve the current rise time less than 100 ns with
optimum surrounding circuit elements, and to establish astacking technique to produce higher voltage and larger
current for hadron kicker systems finally.

vacuum tube has a drawback of limited lifetime, so it
should be replaced to an all-solid-state element with alonger lifetime as possible.
This paper describes the preliminary demonstration
results using SIThs.
KickerCurrent
Magnets width rise[Jls] [ns]BK1-4
0.2 50MK1,20.2 50
MK3-5
0.2 50
AIK0.2 50
AEK
1.4 80FX2-8
1.1 80PFK
0.9 80BIK
3.0 K1- 11
1.2 80MIK
1.2 80MEK
6.0 80
KLHC
25.0 80

1 INTRODUCTION
In order to improve the reliability and lifetime of apulsed power supply and a high voltage switching,
semiconductor-switching devices have been desired toreplace the thyratron tubes. Recently, pulse andswitching operations of several tens kV using IGBT andMOSFET have been developed [1]. We notice the turnon characteristics of the SI-thyristor (SITh). SITh isattractive of the attention for its large current gradientdlldt- 100 KA/Jls as equivalent to a thyratron and it has
been attempted to use as a klystron modulator [2] and ahigh repetition modulator [3] for an induction
accelerator[4] recently. We have started to develop forthe kicker system as one of its application.
Kicker magnet systems are commonly used for an
injection/extraction of particle accelerator rings toproduce a rectangle wave of magnetic field with a fastrise/fall and sufficient flatness. Those kicker magnets aredivided into two types: one is a lumped magnet, which isoften used for larger rings with a long pulse width of 1 30 JlS; the other is a transmission type, used for smallerrings with 20 ns - 1 JlS pulses. Table 1 shows the several
kicker magnets around KEK under operating anddesigning now. All the kicker systems are operated anddesigned with a thyratron switch. However, such aField
rise
[ns]
9212085
85
150
145
400
1000
240
250
1000
1000

PFL
Impestrength Voltage dance
[KG]
[KV]
[Q]
0.40
65
25
0.63
65
25
0.32
65
25
0.32
2565
65
1.00
12.5
0.96
12.5
63
106.2535
lumped
-0.560106060lumpedlumped80

Table 1 : Parameters of kickers.
BK
MK,FX
AIK,AEKPFK
BIKKMIK,MEXKLHC

KEK-PS-BR-extraction
KEK-PS-MR-injection & -ext.
KEK-PS-AR-inj. & -ext. (designed)
KEK-PF-inj.
KEK-B-inj.
JAERIIKEK-BR-ext. (designed)
JAERIIKEK-MR-inj. & ext. (designed)
CERN-LHC (designed)

2 CHARACTERISTICS OF
THE SI-THYRISTOR
SITh has a low on state voltage drop characteristics bymeans of thyristor action followed by the high carrier
injection effect around the gate channel. It has the highspeed switching and low loss characteristics and has hightolerance for electronic noise. These features areespecially remarkable at the high blocking voltage area,
over 3 kV or so. For these high voltage applications,buried gate type SITh is just suitable comparing withanother structures, because of the easiness to get high-262-

The 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

voltage and high conduction characteristics. Especiallyfor the Pulsed Power Application, the high blocking
voltage, high current rise rate and high current
characteristics are quite necessary to get the high powerand high efficiency.
On the other hand, pulse turn-off characteristics isnow under consideration. In order to get the superior
Pulsed Power characteristics, the gate control techniqueis the most important invention.

cables (Hitachi Cables type 20.0/6.0) of 130 m lengthwith 50 n impedance. The end-clipper consists of thediodes (ORUIN MD-065SN1K) and resistors. The
potential at PFL was observed with 5,000 : 1 probe
and the anode current was measured with CT (Pearsonmodel 110) through the 1/19.1 attenuator as shown inFig. 3.

'DCPower
Supplyi------------r·j---r·------------11.

Oscillo-scope (1 Mil)

On(-e5::)thyris~ ,~SI Thyristor Stack
RT103N 15 series-lOOpF

Figure 3: Single test line for a trapezoid pulse switching.

4 EXPERIMENTAL RESULT

Figure 1: 15 series SI-thyristor stack for 40 kV operation.

The PFL is charged by the DC power supply through a
1 Mil resistor. The potential at PFL is decided at a ratioof the resistances, 7.5 Mil I (1+7.5) Mil. Fig. 4 shows atypical wave form of a PFL potential, measured by the5,000: 1 probe in case of Vps = 20 kV charging; bellow
curve shows the same result but in [20 ms/div]. The
measured maximum potential is 17.6 kV, and its ratio isequivalent to the resistance divider. The potential falls tothe ground potential in 0.2 - 0.3 ~s and is recovered asfollows with an electrical time constant tc& from a PFL
capacitance.
lII

-- --

-- --

--1--+ --1--+-~I.llIpe\1
l7.58 v---~-----'.

[.

''.

. .

'~" vv1\r.

-.- .

. - ..

'.

..

. . --.

'l.

1

Figure: 2 SI-Thyristor RT103N.
I- - - ---.~"!

3 EXPERIMENTAL SETUP
Fig. 1 shows the switch used for the test and figure 2shows the structure. The switch has been assembled for aklystron driver [2]. Fifteen SIThs of type RT103N [5],which is reverse conducting with 4 kV hold-off voltage,
are stacked in series to operate for 40 kV. Several diodes
were connected in parallel with each thyristor to protectfrom the emergent large reflected current up to 12 kA.
The trapezoid pulse was produced with the co-axial-263-IV"-----·.DI

1~-.-.

1/, . I·I~-:1.

..

---I

L':l ffJS.

5.0 \}!7.5e 1/---··-..

..

]

Figure 4 : Typical waveform of PFL potential.

'. - .. C[lThe 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

Figures 5 and 6 show the measured anode current incase of VPS = 10 kV, for Z = 50 Q and R = 45 Q (oneline cable load) and Z = 25 Q and R = 24.8 Q (two linesparallel cable load), respectively. The current waveforms
have a notable characteristic of two current risetendencies. One is a former linear rise. This is dominatedby the protection circuit elements around each SITh.
Those parameters were chosen for a klystron driver as
mentioned before. On the other hand, such large
elements are not necessary for the power supply of thekicker magnet, so we can improve the former rise timeby optimising these parameters of protection elements.
The other tendency is a latter exponential rise. This iscaused from a parasitic inductance and can becompensated by inserting speed-up capacitors.

1----.
.2 IJS
200 r'IV-900 r'IV--- ----~·-__.__:=.J-;;y;;;;j--+-,_-t~, -------1---+-f+-+---1--+---ii----1---H--- - - --- I
I

Measured results are summarized in Table 2 for Z =50 or 25 Q and Vps = 10, 20, 30 kV.

5SUMMARY
In order to confirm the feasibility for application ofSITh to the kicker magnet power supply, demonstration
experiment was performed using the prototype SIThpulse modulator, which is making for the klystron driver,connected to the pulse forming line (PFL) with an endclipper. Rise time of 0.3 J.I.S was observed for - 27 kV. It
is possible to use the SITh in the kicker system for alarge lepton accelerator ring at least. It is expected toimprove the current rise time less than 100 ns with
optimum surrounding circuit elements, and to establish astacking technique to produce higher voltage and larger
current for kicker systems in hadron accelerators at last.
The more effort will be necessary to reduce the rise timeless than 100 ns, due to the potential dependence of theSITh turn-ON. We will continue this experiment using
the SITh stacking module for the exclusive use of thePFL.

l,i-++++-l-~ffl.H+t--+++I-+-1-HH+++++++-++-1-++H-++H~H-+++-+-1-H-1:

REFERENCES\\I-· ....

----\- /----+-~~-+-~--\./

Figure 5: Measured current for Z =50 0.

-- -- -/-.-. . -.-~II\io--""'

l·- . . - -..

. ... -- ...
1. --.

.2 IJS
0.58 v
1. 812 v-----\- . -.-\\_\Figure 6: Measured current for Z = 25 0.

1[1] Several presentation at the PAC2001, Chicago.
Akihiro Suzuki et al., T.IEE Japan, Vol.121D,No3,2001, p.308
Akihiro Suzuki et al., T.IEE Japan, Vol.121D,No4,2001, p.453
M. Watanabe et al., Presented at PAC2001, Chicago,
USA (June 18-22, 2001), FPAH042.
S. Ishii : Proceedings of he 14th Symposium of StaticInduction Devices(2001), pp.39.
[2] M. Akemoto et al., Conference Record of the 2000
24th International Power Modulator Symposium,
Norfolk Virginia, USA (June 26-29, 2000), p.205.
[3] E. Hotta, Presented at the 2nd Workshop on theInduction Accelerator Module Development, KEK,Tuskuba, Japan, 30 August 2000.
[4] K. Takayama and J. Kishiro: "Induction
Synchrotron", Nucl.lnst. Meth., A45111(2000)304[5] N. Shimizu et al., 1Oth SI Device Symposium,
SSID-97-6,1997.

Impe~
PS
PFL Current
Gradient
dance Voltage ~oltage rise at anodedYdt[Q][KV] [KV] [ns][KNJJ.S]
108.75 240 (0-95%)50
1.020
17.58 260 (0-95%)
1.3
26.64 240 (0-95%)30
2.02510280(0-86%)
8.75
1.020
17.58 280 (0-86%)
2.026.64 260 (0-86%)
303.2Table 2 : PFL potential and impedance
dependence of Anode current rise time.

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