Research for a high repetitive synchrotron accelerator with the new type of RF cavity using high permeability magnetic alloy

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We developed the first proton FFAG (Fixed Field Alternating Gradient) accelerator in the world. We had already had the electron FFAG accelerator, but the proton FFAG accelerator had not been realized ever.We constructed the PoP (Proof of Principle) FFAG with the new type of RF cavity using high permeability magnetic alloy. In 2002, PoP FFAG could accelerate the proton beam. In principle, FFAG can accelerate the beam in high repetition rate due to the fixed magnetic field. We demonstrated the acceleration within 1msecwhere the proton accelerated from50keV to500keV. We ensure that the possibility of the acceleration in high repetition rate with FFAG Accelerator.For the studies of the basic performance of the PoP FFAG, the "zero chromaticity" of the PoP FFAG was verified experimentally. The zero chromaticity is an important characteristic for FFAG accelerator, which means that betatron tunes do not change during the acceleration. Betatron tunes were measured not only at injection stage bu … More t also during acceleration. The rf knock-out method was employed for the measurement. In addition, an electrode was newly developed and installed for the measurement. According to the experiment, it was verified that the betatron tunes were kept almost constant in the energy range from 50keV to 500keV. For the beam dynamics of a beam transporting system with strong non-linear field, a measurement of the horizontal dynamic aperturewas tried. Anumerical simulation predicts that the PoP FFAG has horizontal acceptance one or two orders of magnitude larger than that of conventional synchrotron.An indirect measurement of horizontal acceptance has been carried out and the results supported the simulation. To measure the acceptance directly, a new beam position monitor, which can measure the beam position and angle simultaneously, was developed. The beam motion in the phase space is expected to be observed directly. The development of the monitor itself had many R＆D issues, but the development has already been done and the monitor was installed in the PoP FFAG. At present, preliminary results of the direct measurement of the dynamic aperture were obtained. Less