S. Sakanaka

Reconstruction for the brilliance-upgrading project of the Photon Factory storage ring

Reconstruction of the Photon Factory storage ring (PF ring; 2.5 GeV) is now in progress to provide very brilliant synchrotron radiation to users, i.e. the emittance is being reduced by a factor of five. Components, such as the quadrupole and sextupole magnets, vacuum chambers, beamlines and beam-position monitors, are being replaced by new ones in 16 normal-cell sections of the PF ring. The accelerating cavities, injection systems and control systems are also being replaced. Operation will commence when the improvements are completed on 1 October 1997.

Observation of the ion trapping phenomenon with bremsstrahlung

Abstract The ion trapping phenomenon was studied at the Photon Factory storage ring. The accumulating process of ions in the electron beam orbit was directly observed by detecting bremsstrahlung from electron-ion collisions.

Vacuum protection system using an interlocked fast-closing valve for a high-power wiggler beam line

The finite-element method was used to calculate a rise in temperature at a fast-closing valve (FCV) blade during exposure to intense synchrotron radiation from a 53-pole wiggler at the 2.5-GeV Photon Factory storage ring. The results indicate a possible meltdown of the titanium-alloy blade within 0.1 s at a maximum beam current of 500 mA, making the vacuum protection function of the FCV ineffective for an instantaneous vacuum failure downstream of the wiggler beam line. In order to prevent the blade from melting, the FCV control system has been interlocked with RF klystrons so as to initiate blade closure after dumping the electron beam by turning off the RF power. Performance tests have shown that the system could dump the electron beam within 95 mu s and then close the blade within 12.4 ms after being triggered. >

Differences in the ion trapping between uniform and partial bunch fillings

Abstract Ion trapping was studied at the Photon Factory storage ring at KEK with bremsstrahlung from electron-ion collisions. Differences in the bremsstrahlung yields were found in the operations between the partial and uniform filling modes. Observed count rates for the uniform bunch filling were always higher than those for the partial filling, indicating that a small number of ions were captured in the latter case. The results clearly show the reason why ion-trapping problems can be alleviated in the partial filling.

Commissioning of the PF Ring after the Reconstruction for the Straight‐sections Upgrade

At the 2.5‐GeV ring of the Photon Factory, a large reconstruction of the lattice around the straight sections has been accomplished in 2005. Thus reconstruction is the main part of the straight‐sections upgrade project to rebuild existing undulators and to increase the number of undulator beamlines. As a result of the reconstruction, four short straight sections have been newly created and the lengths of the existing straight sections have been much extended. To exploit the new straight sections, short‐period narrow‐gap undulators which have a sufficiently high brilliance in hard x‐ray range have been developed. The reconstruction work of the ring was completed in a seven‐month shutdown from March to September, 2005. In the area over two thirds of the storage ring, all the quadrupole magnets and all the beam ducts have been renewed and rearranged to construct the new lattice. Recommissioning of the storage ring was finished at the end of October, 2005. Though we made no in‐situ baking for the beam ducts, ...

Present status of Photon Factory Advanced Ring

The upgrade project of the pulse X-ray source PF-AR was successfully completed by the end of 2001. The initial beam current and the lifetime were largely improved. The injection energy was raised from 2.5 GeV to 3.0 GeV, the maximum beam current of 65 mA was achieved. With a new global orbit feedback system, orbit drifts were largely improved.

Development of a broadband HOM load for the 714-MHz HOM-damped cavity

A 714-MHz higher-order-mode (HOM) damped cavity was developed at KEK, and two cavities of this design are under operation in the Accelerator Test Facility (ATF) damping ring. Each cavity is equipped with four waveguide ports to extract HOM power. In order to achieve the very low HOM impedance required for the damping ring, each waveguide port should be terminated by a broadband, low-reflection load. We have developed a broadband HOM load for this purpose. We describe the design, construction and RF characteristics of the HOM load.

The vertical emittance in the ATF damping ring

Abstract The results of calculations and simulations of the vertical emittance in the KEK Accelerator Test Facility damping ring are described. Both systematic and random alignment tolerances and a skew correction scheme are presented which limit the normalized vertical emittance to γϵ y −8 m rad. The effect of intrabeam scattering on the vertical emittance is calculated.

Collective effects in single bunch mode at the Photon factory storage ring

The bunch length and width in the single bunch mode were measured as a function of bunch current. Bunch lengthening and widening were observed and compared with theoretical models of potential-well distortion and microwave instability. The experimental data was found to agree with these theoretical models. At the same time, the longitudinal effective impedance was obtained. The coherent betatron tune shifts were also observed. The tune shifts were explained with the head-tail mode theory, which gave an estimate of the horizontal and vertical effective impedances.<<ETX>>

New Upgrade Project for the Photon Factory Storage Ring

A new project for upgrading the 2.5‐GeV Photon Factory (PF) storage ring is now being undertaken to create six new short‐straight sections and to lengthen the existing eight straight sections. The short‐straight sections will provide an opportunity to install short‐period narrow‐gap undulators, while the extensions of existing straight sections will be taken advantage of updating current insertion devices to the latest models in future. To this end, the lattice configuration around the straight sections is modified by replacing old quadrupole magnets with new shorter ones and placing them closer to the near‐by bending magnets. Necessary replacement of the vacuum ducts and the beamline front ends will be carried out together. This project will be completed by the end of September, 2005, after six months of shutdown.