Superconducting radio frequency (SRF) cavities were used for storage rings like TRISTAN at KEK, HERA at DESY and LEP-II at CERN in 1990-2000. This technology has been accepted as a common accelerator technology. In August 2004, ITPR recommended an electron/positron linear collider based on SRF technology for the future high energy physics. ICFA accepted the recommendation and named it ILC (International Linear Collider). SRF cavities have a very unique feature due to its very small surface resistance. Energy recovery is another very exciting application. Many laboratories are proposing ERL (Energy Recovery LINAC) as a next bright photon source. In these accelerators, production of SRF cavities with reliably high performance is the most important issue. In this paper the activities of ILC high gradient cavities will be introduced. ERL activity will be briefly presented.
National Synchrotron Light Source II (NSLS-II) is a 3-GeV, 792-meter circumference, 3rd generation synchrotron radiation facility being constructed at Brookhaven National Laboratory. It will replace the existing NSLS, a three-decade old, 2nd-generation light source. To deliver photon beams with <1 nm spatial resolution and 0.1 meV energy resolution for the users, NSLS-II will have extremely high brightness, flux and stability; and ultra low emittance of ≤1 nm-rad. The design of the storage ring and the vacuum systems will be presented, with emphasis on beam vacuum chamber design, fabrication, ultrahigh vacuum pumping arrangement, photon beam tracking, absorber positioning and pressure profiles.
Several new vacuum components have been developed for the XFEL/SPring-8 project. Vacuum waveguide flanges were successfully developed. These flanges provide both RF seal and vacuum seal. The vacuum seal mechanism of these flanges can make seal completely even with a deep scratch on the gasket. Solid-lubricated clean bolt and nut were developed for this flange to avoid organic dust pollution in the vacuum that induces RF discharge. A small RF contact for 28 mm inside diameter bellows was developed. This free ends structure RF contact can move freely in all directions and realize large displacement. The vacuum system of in-vacuum type undulator that commonly used in the accelerators is also described briefly.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the electron neutrino mass with an unprecedented sensitivity of 0.2 eV/c2, using β-electrons from tritium decay. Super-conducting magnets will guide the electrons through a vacuum beam-line from the gaseous tritium source through a differential pumping section to a high resolution spectrometer, where the kinetic energy will be measured. This paper will give an overview of the complex vacuum system of the KATRIN experiment and presents first results of the vacuum performance of the spectrometer. Background considerations require a vacuum of 10-11 mbar or better in the large spectrometer vessel (1240 m3). A combination of NEG pumps and cascaded turbo-molecular pumps will provide the necessary pumping speed. First measurements of outgassing rates after baking the stainless steel vessel (316LN) at 350°C are reported here.
The CERN Large Hadron Collider (LHC) with its 26.7 km of circumference and three different vacuum systems for the beams and insulation vacuum for magnets and liquid helium transfer lines, will have the world's largest vacuum system operating over a wide range of pressures and employing an impressive array of vacuum technologies. This system is composed by 54 km of UHV vacuum for the circulating beams and 50 km of insulation vacuum. Over the 54 km of UHV beam vacuum, 48 km of this are at cryogenic temperature (1.9 K). The remaining 6 km of beam vacuum containing the insertions for “cleaning” the proton beams, radiofrequency cavities for accelerating the protons as well as beam-monitoring equipment is at ambient temperature and uses non-evaporable getter (NEG) coatings. The noble gases and methane is pumped out by 780 ion pumps. Pressure readings are provided by 170 Bayard-Alpert gauges and 1084 gauges (Pirani and cold cathode Penning). The cryogenic insulation vacuums while technically less demanding, impress by their size (50 km) and volume (15000 m3). Once roughed using mechanical pumps, the vacuum relies on the cryopumping which allows reaching pressure in the 10-4 Pa range.
Fabrication of isotopically enriched silicon thin film by plasma-enhanced chemical vapor deposition (PE-CVD) has been performed with source gas mixtures of SiF4, H2 and Ar. Enriched SiF4 gases with 30Si exceeding 25% were obtained from isotopically selective infrared multiphoton dissociation of hexafluorodisilane. The crystalline silicon films were successfully grown by a remote type microwave PE-CVD system on a quartz glass and Si wafers at substrate temperature of 623-1023 K. Secondary ion mass spectroscopy and energy-dispersive X-ray spectroscopy analyses indicated that the films had small impurity contents. The isotopic fraction of the grown Si film almost coincided with that of source gas.