摘要:

A friction-free suspensionin vacuois provided for a graphite disk by magnetic induction. The disk rotates round a vertical line of force inside a properly designed stator; when the stator is cooled, a thermomolecular torque is developed and the acceleration thus given to the disk is measured by an automatic device. It is shown that this acceleration depends only on the geometrical design of the manometer and on the pressure, to which it is proportional. The manometer unit is passive, very small, and insensitive to vibrations and shocks affecting the vacuum setup. The lower limit of its range of measurement is less than10−10Torr. When stator cooling is removed, the disk is influenced only by a (smaller) molecular damping torque. This depends on the composition of the residual atmosphere; provided this is known, the magnitude of the damping can be computeda prioriwith good precision so that the instrument becomes a useful standard manometer for calibration in the10−3to10−7Torr range.

ISSN:0022-5355    

DOI:10.1116/1.1492679

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

Prebreakdown and breakdown electrical properties, and also the light emitted during destructive breakdown, have been studied in thin-film capacitors with the dielectrics SiO,MgF2,CaF2,CeF3,CeO2, and Teflon. Capacitors were formed on glass substrates and had dielectric thicknesses from 900 to 16000 Å. At temperatures between 80 and 380 K, breakdown characteristics are found to be independent of prebreakdown ac and dc conduction. All of the materials studied show a threshold field for the onset of breakdown (on the order of106 V/cm) that is almost temperature independent and varies with dielectric thicknesswapproximately asw−1/2. All materials also have a threshold voltage for the cessation of breakdown which is typically between 10 and 20 V. The light emitted during breakdown contains the arc spectra of the dielectric and the two electrodes. Intensity of single wavelengths of light were recorded simultaneously with voltage waveforms and show that all lines are emitted from the very beginning of breakdown conduction. Hence, breakdown conduction is due to the formation of a gaseous arc. This arc, formed in less than10−8sec, carries the high current characteristic of breakdown and causes destruction of the dielectric.

ISSN:0022-5355    

DOI:10.1116/1.1492680

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

A method to eliminate “argon instability” in a Penning cold-cathode ion pump is proposed. This method involves the use of a metal having a high sputtering yield coefficient as one of the cathodes. The results obtained using titanium and tantalum as cathodes are described. This combination has eliminated the pressure fluctuations while pumping inert gases. The performance characteristics on gases such as air, nitrogen, hydrogen, argon, and helium are also given.

ISSN:0022-5355    

DOI:10.1116/1.1492681

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

The resistivity, temperature coefficient of resistance (TCR), and structure of annealed films deposited by de diode sputtering have been studied as a function of chromium content over the range 17–33 at.% Cr. The resistivity decreases from 0.1 to 0.001 Ω cm and the TCR changes from −1500 to +500 ppm/°C with increasing Cr content. Films containing about 27 at.% Cr had the lowest TCR. Films deposited at a cathode potential of 10 kV have a more positive TCR for the same resistivity than films sputtered at 2.5 kV. Electron micrographs showed the latter films to have a coarser structure—due either to a larger grain size (150 Ă compared to 50 Å) or to a clumping of grains. Electron diffraction patterns indicated a nearly amorphous film;CrSi2was the only identifiable phase. The average drift of 50 μm-wide resistors (1 to 25 kΩ/square) during 1800 h at 200 °C (no load) or 125 °C (50 V dc) was ±0.5% after an initial 200 h aging under the same conditions.

ISSN:0022-5355    

DOI:10.1116/1.1492682

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

The pumping speed of a sputter-ion pump for hydrogen may vary over a wide range. At procures below10−8Torr the speed decreases rapidly and cannot be explained as a simple decrease in the discharge current. In the pressure range between10−8and10−6Torr the pumping speed for pure hydrogen is of the same order as that for nitrogen. However, if a second gas having a higher sputtering yield for titanium is also present in sufficient concentration, increases of at least a factor of two are observed in the pumping speed for hydrogen. Finally, at hydrogen pressures above10−6Torr the long-term pumping of pure hydrogen can produce a marked increase in speed. The extent of this increase is reduced by the presence of active gases such as nitrogen, indicating that change of the rate of diffusion of hydrogen into the titanium at room temperature is the principal factor involved.

ISSN:0022-5355    

DOI:10.1116/1.1492683

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

A nude ionization gauge is described in which a shielded collector is used to lower the x-ray current. Pressures as low as4×10−12Torr have been indicated with an estimated x-ray current corresponding to a pressure below2.6×10−12Torr. Calibration of the gauge on an orifice flow-rate system in the pressure range between10−6and10−9Torr with 4-mA emission and a collector to filament voltage of −300 V, yielded a gauge constant of20 Torr−1. For pressure below10−9Torr the buried collector gauge was compared to the bent-beam Helmer gauge. Data from tests performed on the bent beam Helmer gauge are also given. These include a calibration and a plot of gauge constant as a function of emission current in the range between 0.1 and 10 mA.

ISSN:0022-5355    

DOI:10.1116/1.1492684

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

A general molecular-flow network theory applicable to volumes interconnected by small orifices or porous membranes is discussed. Parameters which describe the properties of such orifices and membranes are first defined. Basic theory is then extended to cover operation with mixtures of gases having different molecular weights. Characteristics of several networks with pulsed pressure inputs are then derived. It is shown that the mass-dependent resistance to flow of an orifice or porous membrane makes it possible to use certain molecular-flow networks as gas analyzers. Other networks are described which have potential applications in improving gauge response to rapid pressure fluctuations.

ISSN:0022-5355    

DOI:10.1116/1.1492685

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

Dielectric constant and dissipation factor for films formed by the reactive evaporation of silicon monoxide in oxygen have been measured as a function of deposition rate, oxygen pressure, electrode material, substrate temperature during evaporation, and source temperature. The dielectric properties are shown to depend primarily on the ratio of molecular impingement rates at the substrate ofO2and SiO (p/r), independent of substrate temperature and electrode material. Dissipation factor, but not dielectric constant, is strongly dependent on source temperature. Some dc conductivity and capacitor discharge characteristics are related to thep/rparameter.

ISSN:0022-5355    

DOI:10.1116/1.1492686

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492687

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492688

出版商:American Vacuum Society    

年代:1969

数据来源: AIP