摘要:

A family of U-tube manometers, suitable for use as standard instruments, has been designed and constructed at the National Bureau of Standards to cover the range of pressures from 100 to1 × 10−2Torr. In these instruments the levels of the two liquid surfaces are measured by adjusting micrometers with conical points ground on the ends of the spindles. One hundred-millimeter and 50-mm range mercury manometers, with spindles approaching the liquid surface from above, are used for differential or absolute pressure measurements up to 100 Torr. Pressures less than 3.5 Torr are measured with oil manometers, in which the micrometer spindles approach the surfaces from below. Measurements made with the mercury manometer have an uncertainty of about4 × 10−3Torr plus 8 parts in105of the reading. Measurements made with the oil manometer have an uncertainty of about4 × 10−4Torr plus 1 part in104of the reading.

ISSN:0022-5355    

DOI:10.1116/1.1492509

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

摘要:

Pumping speeds of commercial diode and triode type getter-ion pumps were measured for the gasesH2, He, andN2over the pressure range from below10−10Torr to10−6Torr. At10−10Torr, the pumping speed was about 20% of the speed at10−6Torr, where the pumps attained approximately the rated speed. Pumping speed measurements as a function of time showed that the pumping speed decreased generally less than 25% over a period of one day. Strong saturation was found only for He at pressures above10−7Torr. No significant differences between diode and triode in the pumping speed vs time or pressure curves were observed. In the diode, pump currents were measured. The quantity P·S/I was found to be pressure independent for short pumping times. The numbers (in molecules or atoms pumped per charge) are: 0.5 (H2), 0.6 (He), and 0.2 (N2).

ISSN:0022-5355    

DOI:10.1116/1.1492510

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

摘要:

The flow of cesium vapor from orifices and tubes into vacuum was investigated experimentally. Using a surface ionization gauge, the intensity of the flow field was measured at various angular positions from the center line for Knudsen numbers ranging from approximately 1 to 100. The dependence of the angular distribution and center-line intensity on Knudsen number is reported for cylindrical apertures having length-to-diameter ratios of 0.04, 1.15, 3.03, and 5.63.

ISSN:0022-5355    

DOI:10.1116/1.1492511

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

摘要:

Before metal surfaces can be welded, it is necessary to remove the contamination (oxide) layer on the surface and avoid recontamination of the clean surface by its environment prior to the welding operation. Mechanical abrasion is one way of removing the surface oxide layer used in such processes as friction-welding, roll-bonding, and diffusion-bonding. It would be desirable to have a technique for welding at low temperatures (0.1 to0.4 Tm), with non-distorting, zero-shear type of leading. This paper describes such a process. In a uhv environment (to delay recontamination to very long times), two halves of a tensile specimen are cleaned by argon-ion bombardment, compressed at about 0.8–0.9 yield strength at 0.1 to0.4 Tm, and held at temperature for finite times. The welded specimen is then tensile-tested in the uhv system to evaluate the process. The variables studied are temperature, time, loading, and the need for ion cleaning on various metals. Successful welds were produced in OFHC copper, Ti, and Be.

ISSN:0022-5355    

DOI:10.1116/1.1492512

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

摘要:

An experimental study has been made of the change in coercive force in thin ferromagnetic films when they are removed from a substrate. Only small changes in coercive force were observed for the iron and Permalloy films when the films were detached from the substrate. However, changes of up to 20 Oe were observed in the coercive force of nickel films. The magnitude of the change in the coercive force of nickel upon detaching the film from the substrate increased with film thickness and decreased for higher rates of thin-film deposition. The change of coercive force for nickel deposited on a substrate which has a thermal coefficient of expansion close to that of bulk nickel was essentially zero. The experimental evidence indicates that the observed changes in coercive force are due to differential thermal expansion between the substrate and the thin film.

ISSN:0022-5355    

DOI:10.1116/1.1492513

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

摘要:

Radio-frequency sputtering cannot be used for absolute measurements of sputtering yields because of the spread in energies of the bombarding ions. This paper describes how these yields can be studied by simultaneously sputtering with the insulators other materials with known dc sputtering yields. Silicon and germanium were selected as reference materials. The dielectric materials studied were fused quartz, Pyrex 7740 glass, Pyrex 7059 glass, soda lime glass, and aluminum oxide (Lucalox). The experiments were performed in an Argon atmosphere at3 × 10−3Torr and at rf electrode potentials between 1.3 and 3.9 kV peak-to-peak. The frequency in all experiments was 13.56 MHz. Sputtering yields were found to be highest for fused quartz (0.16 to 0.5 molecules/ion) and lowest for aluminum oxide (0.04 to 0.17 molecules/ion). The data for fused quartz were found to fall between published low-energy yields determined by Langmuir probe and very high-energy yields determined by ion beams.

ISSN:0022-5355    

DOI:10.1116/1.1492514

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

摘要:

Transparent, adherent, amorphous silicon nitride films in the thickness range of 300 to 15000 Å were deposited on a variety of substrate materials by the reactive sputtering technique. The supported glow-discharge approach was found to be superior to glow-discharge sputtering for the preparation of a uniform, stoichiometric film. Electrical, optical, and chemical properties of the film reflect a density that is less than that reported for the bulk nitride.

ISSN:0022-5355    

DOI:10.1116/1.1492515

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492516

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492517

出版商:American Vacuum Society    

年代:1967

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492518

出版商:American Vacuum Society    

年代:1967

数据来源: AIP