MO6PFP018

THE PULSED MAGNET SYSTEM FOR THE SIMULTANEOUS INJECTION
OF KEK-PF AND KEKB RING
T. Mimashi, K. Furukawa, N. Iida, K. Kakihara, M. Kikuchi, T.Miyajima, S. Nagahashi,M. Sato, M. Tawada, A. Ueda, KEK, Tsukuba Ibaraki Japan
T.Kudo, MELCO SC, Tsukuba Ibaraki Japan
K.Iwamoto, S.Kodama, A.Sasagawa, Kyocera Co., Gamo-Gun Shiga Japan
N.Ishii, Tigold Co., Sanmu Chiba Japan
H. Mori, Nichicon Kusatsu Co., Kusatsu Shiga JapanAbstract
The KEK Linac provides the four different energy beams to the four storage rings. The 3.5 GeV
positron and 8 GeV electron beams are injected into KEKB. The 2.5 GeV and 3 GeV electron
beams are delivered to the Photon factory ring (PF) and the Photon factory advanced ring (PF-AR).
To deliver the beam to the KEK-photon factory and KEKB ring simultaneously, the pulsed bending
magnet was installed at the end of KEKB Linac. It makes possible the top up operation of PF ring.

Introduction
In KEKB, electron and positron beams are injected sequentially. It takes 30 seconds to switch thebeam mode. Since the luminosity tuning has been sensitive to the beam condition of each ring, there
is an increased demand to ensure the simultaneous injection of beams into KEKB rings. In addition
to this demand, the top-up operation of the PF ring also required to obtain high-quality experimental
data. In order to satisfy these requirements, three ring simultaneous injection was planed. The
installed pulsed bending magnet is one of the hardware components of this upgrade project.

Parameters
Deflection angle
Max. magnetic field
Magnet Gap (W x H)
Coil
Magnet Core
Max. Repetition rate
Max. Current
Output current wave form
Pulse WidthValue
114 mrad1.36 T
157 x 30
One Turn1m
25 (12.5) Hz
27 (32) kA
Half sinusoid
200 µsec

The specification of the pulsed bending magnet.

Pulsed Magnet SystemMagnet
For the 2.5 GeV electron beam, the magnetic field strength is about 1.22T and the maximum
repetition rate is 25Hz. The magnet system was designed for the beam operation up to 3GeV.
The magnet is a wind frame type magnet. Laminated core was used for the magnet. Thickness of theplate is 0.35mm. The core length is 1m, and the gap height is 30mm. The single turn coil is used.

Power supply and Control System
Photograph of the pulsed bending magnet.

Ceramic Chamber
Picture of the power supply at
the Linac Klystron gallery

Switching thyristor of
the power supply

The schematic diagram of the power supply

The power supply is located in the klystron gallery at the end of lineac and connected with 7m long 40
coaxial cables to the magnet. To reduce the noise, the exclusive earth ground is prepared. The trigger
signal is sent through the optical fibre cable. Mitsubishi FT1000A-50A thyristor was selected for theenergy discharge switch. Total 24 thyristors, 6 series and 4 parallels, were used. The power supply iscontrolled from the remote sight through the Programmable Logic Controller (PLC) supervised by theEPICS system. The local control of the power supply can be done through the touch panel.

Photograph of ceramic chamber

Special removable flange of the ceramic chamber
The ceramic chamber has racetrack type inner wall coated with Ti-Mo. The surface resistance isaround 100!/ !. The special removable flange is used for one side of the chamber so that thechamber can be inserted from one side to the other.

Operation Status

Parameter
Value
Ceramic chamber length
1316.95mm
Ceramic size (inside)
86x16x1200 mm
Ceramic size (Outside)
99x27x1200 mm
Ti coating surface resistance100!/!
Ceramic chamber parameters

The three ring simultaneous injection has been succeeded since April 2009. The beam is injected
into KEKB HER/KEKB LER/PF ring in the 12.5 Hz/12.5Hz/1Hz or 12.5Hz/25Hz/0.5Hz. The
storage beams in the three rings are kept constant and top-up operations of three rings have beensucceeded. The pulsed bending magnet extracts the beam to the PF on 1 Hz or 0.5 Hz at the top-up
mode, and 25Hz to storage the beam from 0.

Summary
The three rings (KEKB LER, HER and PF rings) pulse-to-pulse simultaneous injection started successfully from April 2009. PF top-up
operation improves the data quality. KEKB luminosity tuning has been performed at the constant beam current. The pulsed magnet
selectively extracts the beam to the PF beam transport line.