Shanghai Synchrotron Radiation Facility (SSRF), a 3.5 GeV, 3.9 nm-rad synchrotron radiation light source, started its user operation in May 2009. By the end of 2015, SSRF has served more than 12000 users and produced major experimental results. The SSRF operation achieved a machine availability of >98% and mean time between failure (MTBF)>80 hours. The electron orbit stability in the storage ring is kept within sub-micron levels. A proposal for SSRF Phase-II Project got approval in 2015. It consists of sixteen advanced beamlines, user experimental supports, beamline technique supports and machine upgrade. Free electron laser (FEL) technology is the next focus of SSRF. Shanghai Deep Ultraviolet Free-Electron Laser (SDUV-FEL), a test facility for new FEL principles, has been operated for 5 years and got a serial of important results. Shanghai X-ray Free-Electron Laser (SXFEL), a soft X-ray FEL test facility, started construction at the end of 2014. It will be commissioned in 2017.

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 National Synchrotron Light Source-II (NSLS-II) is the latest storage ring of 3 GeV energy with the horizontal emittance of the electron beam being 0.9 nm.rad. Nine In-Vacuum Undulators (IVUs) are utilized at the NSLS-II as of February 2016. All IVUs have a unique side window derived from the experience from the CHESS facility in Cornell University. An R&D activity called “Vacuum Seal Test” was conducted to ensure the viability of aluminum wire seal. Another R&D activity to develop a measurement system for Cryogenic Permanent Magnet Undulator (CPMU)¹⁾ was also performed. Other in-air devices, namely damping wigglers (DWs) and elliptically polarizing undulators (EPUs) utilize extruded aluminum chambers with Non-Evaporable Getter (NEG) coating. The beam-based integral estimates were obtained from the virtual kicks at the upstream and downstream of the undulator that best fit the measured orbit distortion in a model lattice with Tracy. In some cases, there are fairly large discrepancies between magnetic measurement data and observed integrals by the beam. Beam studies were carried out to explain the discrepancies mentioned earlier. The latest experiences on ID development and commissioning are discussed in conjunction with related activities in the world.

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 For vacuum systems in high-power proton accelerators, compared with those in conventional particle accelerators, there are more challenging requirements in addition to their basic role owing to the existence of a large number of high-energy protons, rapid cycling of the magnetic field, and high radioactivation. In addition, it is necessary to promptly evacuate from the atmospheric pressure to ultra-high vacuum (UHV) and ensure sufficient pumping speed against an additional gas load because of the desorption of ion-induced molecules from the vacuum wall. The vacuum system of the 3 GeV Rapid Cycling Synchrotron (RCS) at the Japan Proton Accelerator Research Complex fulfills such unique requirements of high-power proton accelerators. Many vacuum devices such as turbo molecular pumps with radiation toughness, beam pipes made of alumina ceramics, and titanium beam pipes and bellows were developed in accordance with the design concept of the system. Treatments to minimize both static and dynamic outgassing were also performed, e.g., surface polishing, coating, and vacuum firing. With regard to the performance of the entire vacuum system, rapid evacuation from atmospheric pressure and assurance of UHV during beam operation have been achieved. Responding to the upgradation of the beam power, continuous improvements of the vacuum system have been performed, e.g., beam loss reduction by improving the beam line pressure, in-situ degassing of the kicker magnet, and magnetic shielding via beam pipes and bellows made of soft magnetic material. This report presents vacuum technologies typically used in high-power proton beam accelerators considering the design concept of the RCS vacuum system, developed components, vacuum performance, and recent upgrades.

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 The calibration of vacuum gauges is mainly carried out in two ways; i) using the primary standards in which the readings of a test gauge are compared with the pressures generated by the standard, and ii) by comparison method in which the readings of the gauge under test are compared with the output signal of a secondary standard. The former type of standards are, usually, large and complicated systems comprising of vacuum pumps, chambers, valves, and gauges etc. while the later type are simply vacuum gauges, with superior qualities, which are attached to a properly designed calibration system. The Vacuum Measurement Lab at Korea Research Institute of Standards and Science (KRISS), Rep. of Korea, maintains primary standards as well as systems for calibration by comparison method. The KRISS primary standards can be used for the calibration purpose in the pressure range from ∼10⁻⁷ Pa to 133 kPa. For bilateral as well as key comparison of these standards, KRISS has participated in the past where its standards have good degree of equivalence and hence international recognition, with other national standards like that of NIST, PTB, NPL(UK), etc. Besides, the KRISS Vacuum Measurement Lab also has comparison system which can be used for calibration by comparison method. However, here the KRISS primary vacuum gauge calibration standards are discussed briefly with the aim to provide enough information to the readers in a single paper.

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