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The Photon Factory Advanced Ring (PF-AR) is a synchrotron light source dedicated to X-ray research. Although the PF-AR is usually operated at a stored beam energy of 6.5 GeV, a 5.0 GeV mode is also available for medical application. In the 6.5 GeV mode, the beam current of 60 mA in a single-bunch and the typical lifetime of 15 hrs at the current have been archived. Single-bunch operation for pulsed X-ray and its relatively high beam energy characterize the PF-AR. However, the high-current in single-bunch causes several problems to be solved, such as the temperature rise of some of the vacuum components, a pressure increase in the ring, and a sudden drop of beam lifetime. In order to avoid these problems, developments of new methods have been continued. In this paper, the status and the recent developments of the PF-AR are presented. It concerns: the successful operation with a two-bunch high-current operation at 5.0 GeV; the vertical beam size control for the medical application; modulating the RF acceleration phase in order to elongate the bunch length; stabilizing temperature in the ring tunnel; the study for medium emittance operation with 160 nm · rad; transferring the RF cavities in order to install a new insertion device; an innovative injection scheme using a pulsed quadrupole magnet.

Effect of a rod type HOM coupler on the accelerating mode in a normal conducting single cell cavity was studied by using MAFIA. Usually, this type of coupler is used to reduce Q-values of some HOMs such as TM011, TM111, TE111, TM021-like modes which have strong E-field in the middle of cylindrical wall of the cavity. We are trying to use this rod type HOM coupler in the off-centred position on the cylindrical wall in order to make it effective for other HOMs such as TM012, TM022-like modes. When it is attached to the position apart from the middle of the cylindrical wall, the coupling with the fundamental mode should be taken into account. Therefore we studied the effect of the rod type HOM coupler on the fundamental mode by the use of MAFIA. The results are presented.

At the 2.5-GeV ring of the Photon Factory, a large-scale reconstruction of its lattice is in progress. The objects of the reconstruction are an increase in number and extensions of the straight sections for insertion devices. Four new straight sections will be created and all existing straight sections will be largely extended. As a result, the number of straight sections for insertion devices will be increased from the currently available seven to thirteen. The newly created straight sections are short in length but will have low beta functions and will be suitable for housing short-period narrow-gap undulators. An invacuum undulator, which has a sufficiently high brilliance within a spectral range for the x-ray research field, is being developed and will be installled. The shutdown for the upgrade project is scheduled for the period from March to September, 2005.

In this paper, we report the operations, troubles, and modifications of an rf system for the 6.5 GeV synchrotron light source PF-AR for the past two years. It includes a strange trouble in one of the cavities, our efforts to recover this cavity, and the work of transferring two cavities from the west to the east rf section.

In the Brookhaven AGS, an adiabatic excitation of longitudinal bunch-shape oscillations was successfully used for producing short proton bunches. We applied this method to electron bunches in the Photon Factory (PF) storage ring at KEK. As a result, the electron bunches could be shortened by a factor of about two by applying an rf voltage modulation. It was also found that another fast excitation of oscillations could be used to produce a little shorter bunches than the original slow excitation method. Both experimental and simulation studies are presented.