982. Vacuum envelopes for ultrahigh vacuum systems

982. Vacuum envelopes for ultrahigh vacuum systems

Classified abstracts 974-986 layers are described. A mechanism for the formation of these pyramids is proposed. J J Tietjen et al, SolM State Electron...

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Classified abstracts 974-986 layers are described. A mechanism for the formation of these pyramids is proposed. J J Tietjen et al, SolM State Electron, 9, 1966, 463-466. 30 974. Vaponr phase growth of gallium arsenide. (Great Britain) Gallium arsenide microwave diodes have been prepared by a novel vapour phase growth technique with the highest combination of reverse breakdown voltages and cut off frequencies reported to date. Results and details inherent to this technique are described. J J Tietjen et al, SolM State Electron, 9, 1966, 1049-1053 30 975. Thin film sputtering equipment. (Great Britain) A hollow enclosure, the walls of which form the cathode, and which enclose the anode, is arranged such that a sputter discharge can be maintained between the enclosure and the anode when the former is evacuated, and provision being made for creating a magnetic field transverse to the direction of the sputter discharge, so as to increase the mean length of the electron paths from the enclosure to the anode. (Author) Int Business Mach Corp, Brit Patent 1,054,660, Patent Abstr, 7 (6) part 6B, 1st Feb 1967, 7. 30 976. Sputter- deposition procedure. (Great Britain) The procedure includes: creating a glow discharge between an anode and a cathode to sputter solid material from the latter; impacting the substrate while the solid is being sputter-deposited with gaseous ions; and controlling the potential of a subsidiary electrode located in the electric field between anode and cathode so that the average kinetic energy of the gaseous ions at impact on the substrate is no greater than the energy level of the ions which would cause saturation by the gas of the solid material being deposited. The method enables accurate control of the growth characteristics of thin films. Int Business Mach Corp, Brit Patent 1,056,060, Patent Abstr, 7 (7a) part 6A, 9th Feb 1967, 1. 3O 977. Cathodic sputtering equipment. (Great Britain) Suitable for the production of magnetic, superconducting and semiconducting thin films, it has both a heating and cooling device for selective use on the same portion of the anode. A temperature sensitive device measures the temperature of this specified portion, by generating an electric signal which in turn controls the heating and cooling devices in order to maintain the temperature constant. The anode is formed of channels such that the coolant maybe circulated. The substrate to be coated is mounted closely adjacent to the anode surface. Int Business Mach Corp, Brit Patent 1,056,985, Patent Abstr, 7 (8) part 6A, 23rd Feb 1967, 1. 30 978. Superconductive metallic film production. (Great Britain) This consists in introducing the substrate to be coated and Nb, Ta or V into a chamber which is then evacuated to a pressure of I ,J 10-5 to 5 × 10 5 torr, evaporating sufficient of the introduced metal(s) to getter oxygen and oxygen-containing compounds within the chamber; and then continuing the evaporation under conditions such that metal evaporated condenses on the substrate at a rate of at least 0.5 microns/hour to form a film capable of exhibiting superconductivity, the substrate being heated to above 25°C for the period during which the film is deposited. (Author) General Electric Co, Brit Patent 1,057,048, Patent Abstr, 7 (8) part 6A, 23rdFeb 1967, 2.

regions of ferroelectric thin films. An electric field of predetermined size and direction is created in the microscope, the object is exposed to this field and a transmission pattern is produced. (Author) Siemens A G, German Patent 1,231,035, Patent Abstr, 7 (4) part D, 26th Jan 1967, 3. 31. EVACUATION AND SEALING 31:37 Melting of nickel at reduced pressure to produce cathodes for electron tubes. See abstract number 1017. 31 981. Time characteristics of vacuum disc switches. (USSR) The effects of the geometry, type of initiation and the initial pressure in the interelectrode gap (in the range of 10-3 to 10 ~ torr) on the value of the delay time of vacuum disc switches were measured. It is shown that the initiation from the cathode gives a shorter delay time than initiation from the anode. The results are discussed. G N Aretov et al, Zh Tekh Fiz, 37 (1), Jan 1967, 131-138 (in Russian). 31 982. Vacuum envelopes for ultrahigh vacuum systems. (USA) The fundamental considerations for design, fabrication and use of ultrahigh vacuum envelopes are discussed. Particular attention is given to the proper choice of materials. Flanging and other accepted joining techniques are considered along with the relative reliability of various glass to metal, and ceramic to metal seals, and the anticipated outgassing rates of these seals. J T Mark, Lubrication Eng, 22, 1966, 398-407. 31 983. Elastic seals. (Great Britain) Suitable for use in an electron beam welding apparatus, the vacuum chamber is designed in two sections and is sealed by an elastic rubber strip in the centre. In alignment with this and located through an opening in the wall, is a workpiece which has a part internal and a part external to the chamber. The workpiece consists of a 'V' shaped groove in which an elastic member is sealed onto a knife edge. Around this circular or semi-circular workpiece an '0" ring seals it to the chamber by compression with a bevelled clamping plate. D Seiaky, Brit Patent 1,054,471, Patent Abstr, 7 (6) part C, Ist Feb 1967, 4. 31 984. High voltage vacuum circuit breaker. (Germany) The circuit breaker has a fixed and a moving contact, arranged in an evacuated housing and connected to a magnetic system for operating the breaker, the system's armature being connected to the moving contact via a plunger. The plunger of a dielectric material is held at the ends and is permanently under the pressure of a compression spring. (Author) Jennings Radio Mfg Corp, German Patent 1,230,883, Patent Abstr, 7 (4) part C, 26th Jan 1967, 6. 31 985. Quick-actlng seal. (Germany) Suitable for pressure vessels or vacuum reservoirs of about 400 to 400 mm diameter, the device consists of a spring situated on the flange of the vessel, which forces the sealing ring through a wedgeshaped thrust ring against the surface of the cover flange and the two side walls. The spring is a fiat metal ring freely movable along its external and internal peripheries. G Seholz, German Patent 1,231,507, Patent Abstr, 7 (5) part A, 2nd Feb 1967, 2. 32. NUCLEONICS

30 979. Vapour deposition of a dielectric material. (Great Britain) A fine metal mesh substrate can be coated with a dielectric material such as a solder glass of low melting point and high lead content, by directing a narrow electron beam onto the fused body of the material. The beam is repeatedly pulsed from a lower to an upper current level to provide proportionate vaporisation of the constituents. The fused body rapidly attains the evaporation temperature of the highest melting point constituent, but does not maintain it long enough for sputtering to occur. Standard Telephones & Cables Ltd, Brit Patent 1,057,239, Patent Abstr, 7 (8) part 6A, 23rd Feb 1967, 3. 30 980. Thin film analysis apparatus. (Germany) An electron microscope is employed for studying the electrical

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32 986. Vacuum problems of the CERN Intersecting Storage Rings. (France) Construction of the CERN Intersecting Storage Rings has started. The rings are expected to begin operating during 1971. They will permit proton-proton collision experiments with the existing 28 GeV CERN synchrotron using colliding beam techniques. Corresponding experiments using one beam and a stationary target would require a 1,700 GeV accelerator. The high beam intensities needed for colliding beam experiments are obtained by accumulation of many hundred particle pulses from the accelerator giving beam intensities of about 20 A. The stored beam lifetime must be of the order of a day, calling for an average pressure in the beam chamber not higher than 10 "~ torr and 10-11 torr is required for the colliding beam regions. Pumping outside the colliding beam region will be achieved by 240 sputter-ion