JAERI-Conf 95-021

2a4-3

DEVELOPMENT OF HIGH DUTY PULSE POWER SUPPLY FOR S-BAND KLYSTRON
K.Satoh,N.Kumazawa,O.Endoh,M.Imagawa,Y.Yamashita,Y.Suzuki,M.Shinohara,
A.Miura,K.Nagatsuka,N.Matsunaga,K.Suzuki,H.Matsumoto,H.Baba,K.Shinohara,
S.Katoh•,Y.kamino•,T.Noguti•,N.Hisanaga•
NIHON KOSHUHA Co.,LTD1119 Nakayama-cho,Midori-ku,Yokohama-shi,Kanagawa-ken,226,Japan•MITSUBISHI HEAVY INDUSTRIES,LTD•NAGOYA AEROSPACE SYSTEMS•10,0ye-cho,Minato-ku,Nagoya-shi,455,Japan

Abstract

Composition

As industrial equipments , we have developed
the line-type pulse modulator for S-Band klystron with 700pps maximum repetition rate and205kW average electric power loss. And then PFN
charging period is about 500uS , charging peakcurrent is 50A and average current is 16A. Especially,we describes an issue on the design andtest results in this paper.

Fig.1 shows the block diagram of klystron modulator and Fig.2 indicate the Klystron mount.
And then Photo.4 shows the thyratron unit.

Introduction
This paper describes the outline and test results of Klystron Pulse Modulator which we havedeveloped as S-Band rf power supply of the industrial equipments in order to operate steadily
with high duty (see Table 1).
Table 1
Parameter of power supply
Klystron beam voltage [kV]140
Klystron beam current [A]108
Gun voltage [kV]
150 CONSTANT
Gun current [A]
0.7 CONSTANT
Pulse width [uS] flat top
14-3dB
19.2
Pulse stability and flatness [%] ±0. 7
Pulse rise time [uS]2.5
Pulse repetition [ppS]
60-700

Fig.2 Klystron mountL1

Fig.1 Block diagram of this klystron modulator-212-L2L3JAERI-Conf 95-021

Table 3
Parameter of thyristor

Design point
1. Selection of switching device:
Thyratron is used in general for the switchof high voltage and high current . As to thethyratron as satisfying to Table 2 , we havechose the big tube, CX-1720MN which has a effective result after discussion with EEV(Maker ofthyratron).

PFN charging voltage [KV]PFN charging[A]
Peak current[A]
RMS current
Average current [A]Max.rating
50
331080 5000
2514.425

2. Use of command charging system5030
163-1. Research for the SCR break down voltage
In case of high speed thyristor , the peak
repetitious opposite voltage is about 2500V atthe maximum, if required as Table 3,it is better
to use in series /30pcs according to the deviceof dilating break down voltage, and then we use
6pcs per 1 stack , ie using 5 stack. And alsousing high speed thyristor(turn off time <40uS)
was adopted in order to keep the precision ofcharging voltage.

Table 2
Parameter for operating switching device
PFN charging voltage [KV]PFN peak current [A]PFN average current [A]Recovery time [uS]33

One of specifications in thyratron , there is
problem of recovery time . In order to recoverthyratron , it should be kept over 25uS at condition of Anode voltage below 100V after stopping thyratron. Therefore, thyristor is used forthe switch in order to turn on or turn off thecharging voltage • Thyratron surely was recovered by trigger timing as Fig.3.

3-2. SCR gate trigger system
It is required to put the reliable gate trigger in order to operate surely all of SCR/30pcs
at the same time without failure , and then it
is operate by the insulated pulse transformer
which is able to endure 40kV . Fig.4 shows theconfiguration of the insulated pulse transformer for SCR gate trigger unit.

------------------ ----·---..

33k v

Charging
voltage
waveform

SCASec20V/4AJl

0 v,'--------Trigger.
source~~~~~~
de-Q

I---~~~------~.----~-+i--~~
I~1 500PS {llr300PS)fl._______

I:

1t i min g -+:_______;_~--------.....l~..___,_I

Thyratron-T;E________1_·_2_2_m_s_______.....~)rL

Fig.3 Block diagram of trigger timing

Fig.4 Configuration of the insulated pulse
transformer for SCR gate trigger unit

3. Selection of SCR thyristor for holdoff of command charging system
The SCR thyristor is required to satisfy
Table 3 , and so there are two important anissue . One is the research for the SCR break
down voltage (3-1) • The other is the SCR gate
trigger system (3-2).

4. Treatment for noise
With regard to noise treatment , we bind thesheet copper (width 365mm , thickness 0.1mm)tobottom of enclosure and between enclosure andklystron • Then we have succeeded to operate
surely this equipment without any trouble-213-JAERI-Conf

95-021

Test results

Photo.3
Up Charging voltage 33kV
Down de-Q timing of trigger

Picture 1 through 3 shows the wave form ateach position for this line-type pulse modulator , and then these wave form have indicatedreally steady operation without disturbance due
to noise.
Photo.lUp
rf output power 5.5MWpeak
Down Klystron beam voltage 140kVpeak

UpDown5kV/div
5V/div

500uS/div
500uS/divConclusion
UpDown50mV/div
20kV/div

5uS/div
5uS/div

We have succeeded to develop the pulse power
supply at the first achievement in the world
which has gained pulse width 14uS and the pulse
repetition 700pps.

Photo.2
Up de-Q R current 300Apeak
Middle de-Q current
800Apeakdown de-Q C current 800Apeak

Up/Middle/Down 200A/div 200uS/div

Photo.4 Thyratron unit for forced oil cooling-214-