NSRRC, Hsinchu
National Tsing Hua University, Hsinchu
The Taiwan Photon Source (TPS) vacuum system has been designed for a 3 GeV electron storage ring of 24DBA lattice, 518.4 m circumference, 24 unit cells and 24 long straight sections of 6 in 12 m and 18 in 7 m. The vacuum ducts for each cell made from thick aluminum plates and extruded aluminum beam pipes will be precisely machined and welded for obtaining a low impedance with small quantity of flanges and bellows. The beam ducts in long straight sections will be flat extruded aluminum pipes of 10 mm vertical height inside which will be ready for installation of the undulators without breaking the vacuum. The BPMs, 2 in each straight sections and 5 in each cells, will be fixed on the ground or on the girder rigidly through the strong supports maintaining a displacement of < 0.1 micron against the stress force of 10 kg from the beam ducts. The small aperture of 10 mm inside the aluminum bending chamber rejects the PSD outgas from the crotch absorbers backfilled to the beam channel, while the surface of bending chamber will be cleaned with ozonated water to reach lower thermal outgassing rate that maintains a much lower averaged pressure below 100 nPa inside the beam ducts.
NSRRC, Hsinchu
Front End (FE) is the first area shapes radiation power to suit the need not only for protection but also for the beam line uses. About 14m long FE vacuum system will connect the ultra high vacuum (UHV) storage ring and beam line in Taiwan Photon Source (TPS). The Fixed mask (FM), photon absorber (PAB) and slit are the major high gas load components, especially in insertion Devices (ID) front ends, because of the synchrotron radiation. From the P(pressure)=Q(outgas)/S(pump) formula, there are some issues will be concerned to get lower vacuum pressure: The low outgassing rate of the vacuum chamber (Qthermal), the localization of the the pumps (IP and NEG) to pump down the outgassing of the photon simulated desorption(Qpsd), and the arrangement of the aperture and gas load . The basic pressure distribution of the bending magnet (BM) and ID front ends will be discussed.
NSRRC, Hsinchu
National Tsing Hua University, Hsinchu
The Taiwan Light Source (TLS), a third generation accelerator, has been operated successfully since 1993. It has been upgraded to increase the beam energy from 1.3 GeV to 1.5 GeV and the consequent capability of full energy injection afterwards. While the beam current has been increased from 200 mA to 300 mA after replacement of RF cavities with superconducting one. The vacuum pressure tends to decrease continuously after installations of 3 undulators and 4 wigglers as well as the new front ends. The accumulated beam dose increased faster up to > 14500 Ah after the routine operational top-up mode since 2006 with average pressure has been maintained below 0.13 nPa/mA. The beam life time of 6 hours at 300 mA has been kept with a limitation of Touschek life time at a stable beam with variation of photon flux < 0.05%. However, the photon absorbers of front ends have been replaced with new ones for subjecting the higher irradiation power after upgrading. The good dynamic pressure reflects the effective pumping performance. The experiences of components failures will be summarized in this paper.
