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The accelerator magnet power supply is an important and unique field for the power electronic devices, such as thyristor, GTO, IGBT, IEGT so on. In this report, authors will introduce the power supply system for the synchrotron accelerator magnet, for example, KEK 12 GeV-PS, J-PARC and then pulsed magnet power supply. more...

Crab cavities have been installed in the KEKB B-factory rings to compensate the crossing angle at the collision point and thus increase luminosity. The beam operation with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is necessary and under way to reach the prediction of simulation. more...

KEKB has been operating with crab cavities for the first time in the world. This paper represents beam operation with the crab crossing.

The main ring magnet power supply for the KEK 12 GeV power supply consists of several 12-pulse thyristor rectifiers, DC filters, reactive power compensators, AC harmonic filters, and analog-digital control systems. Although a DC low-pass filter is effective for reducing the logical ripples over a few hundred hertz, lower-frequency uncharacteristic ripple components may be on the same order as or larger than logical ripples depending on the network condition. Some techniques for reducing these uncharacteristic ripple components are described. > more...

The main ring magnet power supply of the Japan National Laboratory for High-Energy Physics (KEK) 12-GeV PS (proton synchrotron) consists of several twelve-pulse thyristor rectifiers with DC filters, two reactive power compensators with tuned AC harmonic filter and an analog and digital hybrid control system. This magnet power system was upgraded to extend the flat top. The current capability of the bending magnet power supply has been increased, and the analog and hybrid control system was remade in the past decade. Eight twelve-pulse rectifiers for the bending magnets are still controlled by six groups of voltage patterns. The hybrid control system with the analog automatic current regulator and automatic voltage regulator loops, as real-time negative feedback control, and repetitive current and voltage control algorithms have been implemented. This upgrade makes it possible to perform stable operation of the PS and to achieve the most effective utilization of the slow extracted beam spill. After the last upgrade of the reactive power compensator and the multicomputer control system, a flat-top current precision in the 10/sup -5/ range was obtained. > more...

In order to use the slow extracted beam of the KEK (Japan National Laboratory for High Energy Physics) proton synchrotron more effectively, the period of slow extraction has been extended. An upgrade of the main ring magnet power supply is described. The main power supply consists of thyristor rectifiers, DC filters, reactive power compensators, AC harmonic filters and control systems. To increase the current capacity during flat top, the rectifiers and transformers were improved. The AC network and DC filters were left unchanged, since the acceleration and deceleration times were not varied. Analog control devices and the computer control software have also been improved to realize a 2 s flat top with a 4 s repetition rate, compared with the former 0.6 s flat top with a 2.5 s repetition rate. > more...