Showing papers in "Vacuum in 1968"

TL;DR: In this article, the authors reviewed the pre-breakdown phenomena (leakage currents, outgassing and luminosity) that arise across a solid insulator held between two electrodes in a vacuum gap, and the factors that affect the magnitude of the breakdown voltage (conditioning, electrode and insulator material and surface finish, insulator length and shape, pressure, etc).

TL;DR: In this paper, the thermal breakdown of polyethylene and PTFE has been studied by means of an MS 10 Mass Spectrometer, and traces are presented which show that polyethylenes degrades to homologous series of hydrocarbons including the paraffins, olefins and higher order acetylenes.

TL;DR: In this paper, the critical breakdown field strength, E B, is measured for molybdenum, stainless steel and copper, and it is confirmed that E B is independent of the separation of electrodes and is characteristic of the material, even in environments ranging from ultrahigh vacuum (residual pressure about 10 −10 torr) to mercury vapour at pressures of order 10 −3 torr.

TL;DR: In this paper, the surface potentials of metals in vacuum within the 10 −5 to 10 −7 torr range were measured by the means of an improved Kelvin probe, and the life of those local modifications of potentials were highly pressure dependent.

TL;DR: In this article, it is shown that a tempering function of the form T = Toeat is the appropriate form to use, if one wishes to readily interpret activation energies for desorption and diffusion from experimental studies.

TL;DR: In this article, the authors measured the permeability of a porous material by measuring with a flowmeter the amount of gas flowing through it under an absolute pressure gradient, and the same has been done with model materials.

TL;DR: In this article, a differentially pumped 60° mass spectrometer was used to examine the atmosphere above an untrapped rotary pump and also examine the efficiency of various trapping arrangements.

TL;DR: In this article, the main vacuum chamber is serviced by fourteen flanged access ports incorporating metal gasket seals, and the associated devices mounted througj these ports allow in situ cleavage of substrate crystals which can be maintained at known temperatures.

TL;DR: In this article, it was shown that the vapour in which the main discharge develops originates at the cathode for gaps up to about 0.5 cm, and at the anodes for gaps greater than this.

TL;DR: In this article, a technique for depositing insulating layers, onto suitable substrates, by the mechanism of sputtering in a radio-frequency excited discharge was described, and a detailed examination of the electrical properties of sputtered barium-alumino-silicate glass thin film capacitors was made by sandwiching the dielectric layers between vacuumdeposited aluminium electrodes.

TL;DR: In this paper, the measurements of ultraviolet reflectance change in mirrors, caused by oil contamination, are described, and the observed phenomena give a more complete picture of the contamination process than existed previously.

TL;DR: In this paper, a mathematical method for the description of molecular motions in a high vacuum system with adsorbing walls is proposed, where the fundamental quantities, i.e., sorbing and outgassing characteristics, geometrical co-ordination between surface elements, the position of a point internal to the system with respect to the surfaces, are all represented by matrices and vectors.

TL;DR: In this article, it is shown that, for small gaps between clean metal electrodes, satisfactory explanations may be found for the initiation and development of electrical discharges in vacuum, based on a detailed analysis of the electron field emission from the cathode and the associated current thermal interaction with either electrode.

TL;DR: In this article, an adsorption foreline trap suitable for conventionally pumped quick cycling vacuum systems has been evolved, where the main consideration was the reduction of water vapour take up by the trap adsorbent during pumping operations.

TL;DR: In this article, a simple device consisting of a magnetic ball valve and condenser was added to McLeod gauge manometers to obstruct the flow of mercury vapour from reservoir to cold trap thereby eliminating the pressure gradient between gauge and trap sustained by mercury streaming in conventional systems.

TL;DR: In this paper, polycrystalline tungsten and gold ribbon targets were bombarded with low-energy inert gas ions of helium, argon and krypton, and work function recovery was monitored during post-bombardment step annealing studies.

TL;DR: In this article, a procedure for absolute calibration of vacuum gauges for tritium gas is described, which depends upon measuring the radioactive decay current generated by a known volume of Tritium.

TL;DR: In this paper, two separate versions of the electric quadrupole mass filter are described, and the design parameters for a mass spectrometer helium leak detector with a sensitivity of 1 × 10 −11 litre torr/sec at a port speed of 10 litre/sec are compared with the requirements for an analytical residual gas analyzer with unit mass resolving power at mass 100 and a sensitivity 1 amp/torr.

TL;DR: In this paper, the authors studied the effect of pre-breakdown discharges on the apparent dielectric strength of polyethylene-terephthalate insulation under high vacuum.

TL;DR: In this article, a discussion regarding the value of τ 0 the preexponential factor in the Frenkel equation for the desorption from glass of ionically pumped noble gases is presented.

TL;DR: In this article, it was shown that plasma traps will need to be filted at regular intervals to confine damage to a reasonable length, and it was concluded that the plasma traps should be filtrated at each interval to prevent an arc from forming in a vacuum insulated power cable.

TL;DR: In this paper, the effect of hot filament ionization sources on the residual gases in two UHV systems has been investigated by observing the interaction of Bayard-Alpert gauges with two different mass spectrometers.

TL;DR: In this article, the ion-current pressure characteristics show that the two modulator gauges have a most probable error of ±50 per cent at a pressure of approximately 5×10−11 torr.

TL;DR: A Bayard-Alpert ionization gauge with end-caps on the grid has been found by many workers to have a higher sensitivity than one with an open-ended grid.

TL;DR: In this paper, various types of vacuum gauges available, particularly the more popular types such as thermal conductivity gauges, cold cathode ionization gauges and hot cathodes ionization gaudes, are reviewed.

TL;DR: In this article, an apparatus was described that allows electrical discharge phenomena to be investigated in uniform electric fields with gap lengths of up to 6 cm, applied voltages up to 300 kV and gas pressures from 10 −8 torr to 4 atmospheres.

TL;DR: In this article, the construction of a demountable tritium ionisation gauge is described, suitable for measuring total pressures between 5 × 10 −4 and 200 torr of all gases in a metal vacuum system.

TL;DR: In this paper, the authors presented the sealing process of concentrically and helically machined surfaces with two different roughness profiles: a radial and a circumferential one, and the results of specific factors resulting from these equations are computed as a function of the geometric parameters of the seal.