| Paper | Title | Page |
|---|---|---|
| WEPEA031 | Suppression of Horizontal Beam Oscillation by using Fast Kicker Magnet System in SPring-8 Storage Ring | 2552 |
|
||
|
In top-up operation at SPring-8 the horizontal beam oscillation had been excited because the injection bump orbit is not closed perfectly. For this problem, we had made an effort to reduce the residual beam oscillation by the improvement of bump magnet design, reducing the effect due to the nonlinearity of sextupole magnet and introducing pulsed corrector magnet, etc. By these improvements the average amplitude of residual oscillation has now been suppressed to the level of less than 0.1 mm. Still remaining relatively large residual oscillation comes from a non-similarity of a temporal shape of magnetic field of four bump magnets. We then started development fast kicker magnet system to give a counter kick to this part of residual beam oscillation. A key technology in this development is how to generate a large pulsed current in a short period to meet the oscillation characteristic. A newly developed fast pulsed power supply can generate a current of about 300 A, or corresponding magnetic field of 4.61 mT, with a pulse width of 1.2 us. Recently, we succeeded in the reduction of the horizontal beam oscillation at the timing of firing bump magnets by using this kicker system. |
||
| WEPEA032 | Design Study of a very Low-emittance Storage Ring for the Future Upgrade Plan of SPring-8 | 2555 |
|
||
|
The SPring-8 storage ring has been operated for more than ten years and provided brilliant hard X-ray radiation to users. In recent years there are some discussions on upgrade plans of existing synchrotron radiation facilities and proposals of new facilities. In these the target brilliance of photons is set to be comparable or even higher, in some energy range, than that of the present value of SPring-8. At SPring-8 a design study of a new storage ring is now in progress for the future upgrade plan. The lattice structure will be changed from the present double-bend type to the multi-bend one, keeping the source position of all insertion devices unchanged. The emittance will be lowered from the present value of 3.4nmrad at 8GeV to 0.4nmrad at 6GeV (or 0.8nmrad at 8GeV) in the case of triple-bend lattice and 0.2nmrad at 6GeV (or 0.3nmrad at 8GeV) in the case of quadruple-bend lattice. We will report the present state of our preliminary work on lattice design. Nonlinear resonance correction to enlarge the dynamic aperture for on- and off-momentum electrons will also be discussed. |
||
| THPD090 | Design of Modified Lattice of Long Straight Section in the SPring-8 Storage Ring | 4497 |
|
||
|
A set of three in-vacuum undulators is going to be installed in one of four long straight sections of the SPring-8 storage ring. In order to make the undulator gap as narrow as possible, we plan to divide this long straight section into three sub-sections and install quadrupole magnets between these sub-sections to lower the vertical betatron function. In the modified lattice, however, the symmetry of the ring is lowered and in general it becomes difficult to keep a sufficient dynamic aperture for on- and off-momentum electrons. The long straight sections were originally introduced in the year 2000 and at that time we developed a method of "quasi-transparent matching of sextupole fields" where two key concepts of betatron phase matching and local chromaticity correction were combined to obtain a sufficient dynamic aperture and momentum acceptance. Then, in the year 2007 "counter-sextupole magnets" were further installed to cancel the effect due to non-linear kick by sextupole magnets used for local chromaticity correction. In designing the new lattice with a modified long straight section, we followed the same line and could recover the dynamic aperture and momentum acceptance. |
||
| THPE067 | Dynamic Aperture Study at the SPring-8 Storage Ring | 4671 |
|
||
|
The dynamic aperture is of importance for high injection efficiency and long lifetime of a storage ring. At the SPring-8 storage ring, a third generation light source facility, various improvements of the dynamic aperture were developed, e.g. the introduction of supplemental sextupole magnets at long straight sections, and the symmetry restoration of linear lattice. To understand the nonlinear dynamics limiting the aperture, the measurements were performed for the various operation conditions with the improvements. Using injection bump magnets and turn-by-turn beam position monitor system, we measured the horizontal dynamic aperture. The Fourier analysis of the oscillation of the kicked beam shows the resonance excitation influential on the dynamic aperture. The knowledge through the experiments is essential to the further improvements of the dynamic aperture of the present ring and the new storage ring design of the future SPring-8 upgrades. |