1. Development of new power supplies for J-PARC MR upgrade
Yoshi Kurimoto (KEK)
for J-PARC accelerator group

2. Contents About J-PARC Main Ring and The upgrades
Capacitive Energy Storage
System Development
Summary

3. Introduction

4. J-PARC Main Ring (MR)
Circumference
1568 m
Injection Energy
3 GeV
Extraction Energy
30 GeV
Repetition Rate
0.4 Hz
RF Frequency
MHz
Number of bunches 8
Synchrotron tune
Betatron tune
22.4, 20.75
MR is currently operated at a beam intensity of 360 kW
Upgrades toward 750 kW are planned !!

5. Synchrotron Repetition Rate
Increasing Repetition Rate from 0.4 Hz to approximately 1 Hz
< 1.3 s
Requirement : Energy Storage
Issue：Large power AC main grid　𝑷=𝑽𝑰= 𝑳 𝒅𝑰 𝒅𝒕 +𝑹𝑰 𝑰
2.56sec cycle
1sec cycle
磁気エネルギーの流れ
~D140MW
Not allowed by Tokyo Electric Power Company
Energy Recovery with Bank Capacitor

6. Capacitive Energy Storage

7. Effect of Capacitive Energy Storage
Conceptual Schematics
Loss Compensation
Magnetic Energy flow
All magnetic energy (~10 MJ for 1 bending family ) is provided from the capacitor energy storage
Only loss is compensated from the main
Input Power can be reduced by 70 %
AC main
Input and Output Power for one power supply
Input Power
Output Power
Dry-type film Capacitor
Requirement for the capacitive energy stroage
Long Lifetime > 10 years ~108 charge-discharge cycles
No internal Short (for safety)

8. Self-Healing Structure
Internal Structure of Film Capacitor
More pixels = Safer
Many small pixel capacitors connect with each other
A pixel capacitor with weak part is isolated by over current
As a result, the capacitance decreases by 1/10000
The lifetime is defined as the time until capacitance decreases by 5 %

9. AC or DC ? For DC voltage For AC voltage (50/60 Hz) Bigger
fewer (Large) pixels to reduce discharge at the surroundings of pixels due to voltage change
Lower voltage (<100 V/mm)
Many (small) pixels
Higher voltage (200 V/mm)
Bigger
Our application (Not 50/60 Hz but only 1 Hz) is the middle of DC and AC
DC Capacitor- based development !!

10. Lifetime test with DC capacitor
Difference of the electrode material
60 Hz (accelerating test by factor 60)
Capacitance Drop (%)
material A
material B
material C
Material C is selected
Time (h)
Extrapolated lifetime (5 % capacitance drop) = 4.5 ×108pulses
Capacitor design was fixed !!
Single capacitor : 2mF 2.5 kV kg

11. System Development

12. Basic Design
Design for new PS for 1 bending magnet family
Same power units are used for both choppers and converters
Developed Capacitor Bank.

13. Test Results with Minimum Hardware
Schematics
Full bridge circuit
Magnetic Energy
Loss Conpenstaion
IEGT
Test Resutls
Output Current
1 s
Single Capacitor :
2500 V 2 mF 29 kg
400A
Capacitor Voltage
~ 3 m
Planed area for new PSs can accommodate all capacitor banks (≈6F)
400V
Total 48 mF
We have successfully controlled energy between the capacitor bank and magnets

14. Other Developments Low Noise Measurement and Digital Control
24 bit A/D board and Isolation between analog and digital componets
PS for Sextupole
Current 200 A
DI/Iref
10-6
（Hz）
Succeed to measure current at ppm level
Digital Control Board for Tracking Error Correction
Tracking error can be reduced down to 10-5
FPGA-CPU board
24 bit A/D Board
Y. Kurimoto et. al. IEEE. TNS

15. Summary
In J-PARC Main Ring, we plan to increase the repetition rate from 0.4 Hz to approximately 1 Hz for 750 kW operation
Power supplies for main magnets needs to be replaced
Power variation with 1 Hz operation must be absorbed on-site
Power supplies using capacitive energy storage has been developed and successfully tested
We aim at replacing all power supplies until the end of FY2018