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Synchrotron Light Sources must operate in the Ultra High Vacuum (UHV) region (10 -9 mbar) in order to obtain satisfactory stored electron beam lifetimes. To achieve this requires meticulous attention to cleanliness. Previous work has been reported in which various methods of chemical cleaning of contaminated stainless steel samples were shown to produce surfaces with suitably low thermal...
The construction of a new asymmetrical collider with 3.5 GeV positron beam and 8 GeV electron beam has started at KEK. The collider consists of two rings with the circumference of 3 km intersecting at the colliding point. The vacuum ducts deal with intense heat from synchrotron radiation because of a high design current, 2.6 A for a positron and 1.1 A for an electron. As a result of the compact design...
We have studied the charging of insulator with double ribs or a recess by using a two dimensional Monte-Carlo simulation method based on the secondary emission electron avalanche (SEEA) mechanism. The electric field distribution on cathode around a triple junction was analyzed taking the charge accumulation into account. Results were compared to those obtained for a simple cylindrical insulator and...
The variety of sealed-off devices requiring a vacuum for their operation has been ever-increasing during the last decades: it includes, CRTs, X-ray tubes, lamps, etc. and also metallic dewars, vacuum insulated pipes and panels, where a vacuum is a thermal insulator, and more recently, flat displays such as FEDs. The gas problems in these devices are generally related to outgassing, microleaking and...
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...
When the whole inner surface of a vacuum chamber is coated with a non-evaporable getter film, very low static and dynamic pressures are expected after activation. In an accelerator environment this could result in a longer beam lifetime, in a lower risk of pressure bumps, and in a lower level of bremsstrahlung radiation due to the beam-gas interactions. To substantiate these favourable characteristics...
This study investigates the outgassing of bare stainless steel and MoS 2 coated ball bearings, both of which are widely used in modern high vacuum technological equipment. Three well-distinguished stages of outgassing are observed as a function of time, which correspond to different phases of a ball bearing's lifetime. For both type of bearings, hydrogen, carbon oxide and methane were the...
Ultrasonic motor is one of the promising actuators that are utilized in ultra-high vacuum (UHV) conditions. The authors have proposed a rotational feedthrough for UHV using a mode-rotational type ultrasonic motor. This rotational feedthrough is distinguished by its arrangement of driving parts. The piezoelectric ceramics and wiring parts were arranged outside the vacuum chamber because they can be...
Non-evaporable thin film getters of various compositions have been produced by sputtering. Among about 20 materials which have been studied, the lowest activation temperature (about 180 o C) has been displayed by a Ti-Zr-V coating obtained from a cathode made of intertwisted elemental wires. In order to optimize the vacuum properties of this film various production parameters, including the...
Progress in modern vacuum technology requires an increasing number of measurements to be performed in the vacuum environment itself and in many applications data transfer outside the vacuum vessels is both difficult and expensive. This paper explores the potential of wireless technology to transmit data from and into ultra high vacuum (UHV) compatible vacuum chambers using glass viewport windows attached...
The insulation vacuum (<10 -4 Pa) of the large hadron collider magnet cryostats, thermally protecting the superconducting magnets which operate at 1.9K in superfluid helium, is divided in to 214m long segments separated by means of insulation vacuum barriers.The insulation vacuum barrier is a leak-tight stainless steel welded structure, composed of two concentric corrugated cylinders...
The true outgassing from surfaces is often masked by the production of gases and pumping within the measuring gauge. Quadrupole mass analysers have been used to measure the outgassing from carefully prepared samples of stainless steel. By using an isolation pressure rise technique coupled to non-evaporable getter pumping, the problem of production of methane by the gauge is overcome and it has been...
The Diamond synchrotron, which is due to come into operation with beam for users in 2007, is being constructed at the Rutherford Appleton Laboratory, Oxford. The design status of the vacuum system of the storage ring as at 31st December 2002 will be reported.Diamond is based on a 24 cell 3GeV electron storage ring of 561.6m circumference. As is the case for most such machines, the operational pressure...
An apparatus for making two-dimensional photon images of tribomicroplasma in controlled gas pressures was constructed. Using the apparatus, the dimensions, patterns, and photon emission intensities of the tribomicroplasma were investigated under various reduced air pressures when sliding a diamond hemisphere pin on a sapphire disk. It was found that the shapes and patterns of the two-dimensional plane...
The paper presents studies on the electrical properties of cylindrical shape samples of insulators made from polyamide, epoxy resin, polymethyl methacrylate, and electrical porcelain, located in vacuum at a pressure of 0.1mPa. The insulator samples had a diameter of 20mm and a height of 1-10mm. The study was performed with an alternating voltage of 50Hz in the range up to 70kV (peak). The examination...
A narrow band-pass filter of subnanometer bandwidth is extremely sensitive to errors in the layer thickness and the optical constant of composite layers. For a filter made by vacuum deposition, such an error may be due to small fluctuations in deposition parameters. The distribution and deposition rate of the evaporating species, the distribution of ion current density and the ion voltage of the ion...
Diffusion bonding of Fe-28Al alloy with Cr18–Ni8 austenitic stainless steel was carried out in vacuum of 10 −4 Pa and a diffusion-bonded Fe-28Al/Cr18–Ni8 joint with diffusion reaction layer was formed. Microstructure and reacted phases in the joint were investigated by means of scanning electron microscope (SEM) and X-ray diffractometry (XRD). The reacted phases in the diffusion reaction layer...
The interfacial structure of the Mg/Al diffusion-bonded joint was studied by means of SEM, EPMA and TEM. The test results indicated that the interface zone of Mg/Al diffusion-bonded joint included the transition region on Mg side, the mid-diffusion region and the transition region on Al side. The concentration distribution of Mg and Al atoms in the diffusion zone includes three different regions....
Fe-28Al(Cr) alloy and low-carbon steel were diffusion bonded in a vacuum of 10 −4 –10 −5 Pa. The relationship of the bond parameters and shear strength at the interface was discussed. Microstructure characteristics and the reaction products at the interface were investigated by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The thickness of the diffusion reaction...
Various functional metal-oxide coatings on glass substrate have the possibility to be used for many applications in these days. For keeping the high performance of these applications, it is very important to understand the adsorption property on those coating surfaces. However, there are few reports about such properties of metal-oxide film surface in vacuum state, especially the carbon adsorption...
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