Power Modulator using Inductive Energy Storage for Induction Synchrotron

1
Power Modulator using Inductive Energy Storage
for Induction Synchrotron

• Eiki Hotta
• Kaoru Hashimoto, Kunihito Yamauchi,
• Masato Watanabe, Akitoshi Okino
• Tokyo Institute of Technology
• Acknowledgment
• SI Thyristors are provided by NGK Insulators Ltd.

2
Outline of Talk

• Principle of Accelerating Voltage Generation
• Testing Circuit Operating Mode
• POP Experimental Results
• Summary

3
Induction Synchrotron
Main Ring
Barrier Bucket Gap
Acceleration Gap
v
v
t
t
Non-symmetric output pulse waveform
Super bunch
Super bunch
Voltage waveforms
4
Inductive Energy Storage
For Induction Synchrotron
Only one switch - Simple circuit
L
R
VR
E
Opening SW
Normally used for Pulse Power System
5
Inductive Energy Storage
Opening switch with high-speed, high-hold-off
voltage is required.
E Accelerating Voltage T Accelerating Pulse
Width
6
Circuit Analysis Laplace Transformation
Laplace transformation after t 0
At t 0
- ET
Laplace transformation
?
Final value theorem
7
Testing Circuit and its Operation
V
t
E
SI Thy (T335R-40) Peak hold off voltage 4000
V
8
Photo of Testing Circuit
MOSFET
Inductor
Load Resister
SI Thy
9
Output Voltage
L 2.6 mH
50 W
V
?Accelerating voltage and reset pulse
Oscillation after the reset pulse Voltage
drop in accelerating voltage
10
Suppression of Oscillation
50 W
Increase the damping factor by connecting Rp
Oscillation after reset pulse is suppressed
11
Cause of Voltage Drop
V
V
Voltage drop in accelerating voltage Charge
career density in SI Thy is low ? Internal
resistance of SI Thy is large ? ON voltage of
SI-Thy is large
By injecting charge, initial career density in
SI-Thy is increased
12
Reduction of Voltage Drop
Gate circuit
By connecting a gate resistor, ON voltage of SI
Thy is reduced and the flatness of the
accelerating voltage is improved.
13
Experiment with Magnetic Core
30 m
Finemet
50 W
Because of mismatch, a little dip in accelerating
voltage and an oscillation after the reset pulse
are observed.
14
Switching Loss of SI Thy.
Larger L ? Lower current ? Reduction of loss
At DC power supply voltage of 250 V, L 2.6 mH,
pulse width 900 ns,
Switching loss is 5.2 mJ
SI ThyJunction temp. 125 ?,Ambient temp. 25
?,Thermal Resistance 0.055 ?/W
?Maximum rep. rate will be about 400 kHz
15
Summary

• Using an SI Thyristor as a high-voltage,
  high-speed opening switch, a power modulator
  using inductive energy storage for induction
  synchrotron was fabricated.
• Generation of an accelerating voltage and a reset
  pulse has been confirmed.
• The power modulator generates the reset pulse
  automatically according to the pulse width and
  height of accelerating voltage.
• The estimated maximum repetition rate is 400 kHz
  under our experimental condition (250 V, 900 ns,
  L2.6 mH) without forced cooling.