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Vacuum cryosystems providing large pumping speeds have been specially constructed to be installed inside cyclotron vacuum chambers, like AGOR (KVI lab at Groningen) or SPIRAL (GANIL-Caen). In such systems, the refrigeration power is supplied by cryogenerators located a few metres away from the cryopanel, and efficiently transferred through dual heatpipes that form closed loops where condensing and...
Discharge gas trapping in thin films produced by sputtering is known to be due to high-energy neutrals bouncing back from the cathode. Qualitatively, the phenomenon is enhanced by raising the discharge voltage and is strongly dependent on the atomic masses of the discharge gas and of the cathode material. In addition to these known effects it is shown that, for a given gas, the trapped amount decreases...
The prototype for the series production of the 400 modules to be built by CNIM is first shortly described after the surface cleaning and 400 o C air firing. The system for the 160 o C bake out, the pumping and measuring bench installed in the CNIM premises are then presented. The results on leak tightness, hydrogen outgassing and residual hydrocarbon contamination are reported and...
The operation of the electron-positron storage ring LEP at an energy of 100GeV leads to the deposition of a high-power flux on the vacuum chamber walls. The high critical energy of the photons emitted as synchrotron light (740keV), places the photon-stimulated desorption in this machine in a completely new energy range compared to the existing electron storage rings. At this high photon energy, the...
TAMA300, a laser interferometric detector for gravitational waves, involves two vacuum ducts (300m long, 400mm in diameter) and eight vacuum chambers (2m high, 1.2m in diameter). All surfaces of the ducts and chambers were finished by electrochemical buffing so as to reduce the outgassing rate. The vacuum system was completed at the beginning of 1998. After 2000h of pumping, the vacuum pressures in...
In order to reduce the activation temperature of the TiZrV alloy, thin films of various compositions were produced by three-cathode magnetron sputtering on stainless-steel substrates. For the characterisation of the activation behaviour the surface chemical composition has been monitored by Auger electron spectroscopy (AES) during specific in situ thermal cycles. The volume elemental composition of...
The status and recent developments of the Elettra vacuum system are reported. Due to the fact that in our facility no in-situ bake out is applied, we focused our work to contribute to the theoretical explanation of the beam cleaning efficiency. Gas injection experiments have been performed introducing various gases into the vacuum chamber of the storage ring. These experiments are very useful and...
The extreme high vacuum integrated process has been developed in order to transfer substrates among vacuum chambers without any contamination on the ultraclean surface. The integrated process has five main line chambers, six sidetrack chambers, connector chambers and six vacuum instrument chambers for surface analyses and film preparation. Magnetic levitation transports are installed into the line...
The reliability of large vacuum systems is largely dependent on the installed hardware and on the procedures established for the production, installation and interventions on such systems.Nonetheless, an essential role is the control of these systems which implies its remote operation, careful survey and proper protection. This allows the operation of the vacuum system - to a certain extent - without...
In this paper, conditioning procedures presently used in tokamaks are described. Long discharge operation has been achieved in the Tore Supra. Moreover, Tore Supra is the only Tokamak in the world which operates with a permanent magnetic field as foreseen in future fusion reactors. Normal glow discharge conditioning appears to be inefficient in this case. Therefore, special conditioning procedures...
The determination of the hydrogen adsorption capacity on different industrial surfaces has been carried out by measuring isothermal adsorption. First results show that the adsorption capacity is mainly determined by surface porosity. Therefore, the samples may be classified into two categories: smooth and porous surfaces. Thermal desorption spectra reveal two adsorption energy levels for hydrogen...
In the near future some precision machining and production processes like lithography will need a controlled gaseous atmosphere or vacuum environment. This paper considers some of the serious problems that are encountered when a large workpiece or substrate has to be positioned with micrometre or nanometre accuracy in a vacuum system. Especially in production machines, which require high speed (21m/s),...
This paper describes the experimental studies of the effect of a dipole field on photoelectron emission and on the photon reflectivities from LHC beam screen material. These studies were performed using synchrotron radiation from the VEPP-2M storage ring at BINP (Novosibirsk). The particular surface roughness and geometry of the prototype LHC beam screen material requires dedicated experimental measurements...
DESY pursues a luminosity upgrade project for the HERA electron-proton collider that foresees an increase of the luminosity by nearly a factor of 5. This is achieved mainly by a completely new layout of the interaction region. The new scheme involves a very early separation of the colliding beams by means of superconducting magnets that are installed inside the experimental detectors. The early beam...
This paper represents a model of a drag pump, to be employed as a part in modern turbo-molecular pumps. The important function of these pumps is their efficient working in the range of medium and high vacuum. The design characteristics of a molecular drag pump, such as, ultimate vacuum, pumping speed, compression ratios, and the efficiency have been experimentally determined. A close proximity has...
Two stainless-steel vacuum chambers, after putting them through a usual laboratory ultrahigh vacuum processing, have been exposed to a white synchrotron radiation photon beam, 3.75keV critical energy at DCI. However, no ''in-situ'' bake out was performed on the vessels before the irradiation. The first test chamber was a simple 130mm diameter circular tube 3.6m in length. Beam scrubbing for a photon...
In order to establish the surface cleaning method for sputter deposition of pure titanium film onto TiNi shape memory alloy substrate, the effects of wiping the substrate surface with cotton gauze soaked with organic solvent on adhesion of the deposited film to the alloy substrate were investigated. The titanium film deposited by DC sputtering onto the alloy substrate surface wiped with the gauze...
Sputter-deposited thin films of TiZrV are fully activated after 24h ''in situ'' heating at 180 o C. This activation temperature is the lowest of some 18 different getter coatings studied so far, and it allows the use of the getter thin film technology with aluminium alloy vacuum chambers, which cannot be baked at temperatures higher than 200 o C. An updated review is given of the most...
Capacitance diaphragm gauges (CDG) are widely used also as transfer instruments; consequently, they need to be referred frequently to primary systems mostly in the (1000-0.1) Pa range where no other accurate gauges are available. They must be characterized individually since a general rule on their metrological behaviour is not possible. Various CDGs are calibrated at IMGC for the Italian Accreditation...
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