摘要:

A differential adiabatic calorimeter for the study of heats of transition in solution is described. The demonstrated sensitivity of the apparatus is such that a heat effect of 35 cal/liter occurring over a temperature range of 7°C was determined with a precision of ±2%. The results agreed with other reported work. The instrument employs solid state electronics and it may be operated from −10 to 90°C.

ISSN:0034-6748    

DOI:10.1063/1.1683762

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Several types of high pressure electrical feedthroughs, principally pipestone cone seals, frozen oil seals, seals made with epoxy, and seals made with ceramically insulated thermocouple wire, are reviewed and evaluated with emphasis on the epoxy and thermocouple wire seals, which are especially suitable for small gas systems.

ISSN:0034-6748    

DOI:10.1063/1.1683763

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A new technique is described for rapid measurement of the thermoelectric power of rod‐shaped specimens over a wide temperature range. The apparatus utilizes sensitive commercial dc amplifier for the sample and temperature gradient voltages and a multiple‐point recorder for sampling these voltages as well as the sample temperature signal. The technique eliminates spurious thermal emf's in the leads and is based upon on‐the‐run recording of the sample and temperature gradient voltages as the temperature gradient slowly increases. As a test of this technique, the thermopower of pure nickel was measured between 4.2 and 300 K and the results are compared with other measurements using conventional techniques.

ISSN:0034-6748    

DOI:10.1063/1.1683764

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

It has been suggested that a cavity is formed in the path of an electron beam and that this cavity accounts for the deep penetration capability of an electron beam welder. An experimental technique utilizing a high energy pulsed x‐ray source was developed to obtain radiographs of the cavity during the actual welding process. These radiographs not only verify the existence of the cavity but also show that it oscillates in size and shape.

ISSN:0034-6748    

DOI:10.1063/1.1683765

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Inexpensive modifications to a commercial GE XRD‐5 x‐ray spectrometer to convert it to step scanning are described. A filter changing mechanism for optional use of the Ross balanced filter method is also described. The modified spectrometer may be used with any counting system which can be controlled by a switch closure. Some data are presented illustrating the use of the modifications in the determinations of atomic radial distribution curves for vitreous selenium.

ISSN:0034-6748    

DOI:10.1063/1.1683766

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A sliding‐shaft type of vacuum lock for a mass spectrometer is described in which the sample carriage and pumping manifold are made entirely of sintered alumina (95% Al2O3). The hardness of this material effectively eliminates any problem of seizing due to entrance of foreign matter or gradual wear of the bearing surfaces. Components of the high voltage ion source are fully insulated when mounted directly on the carriage. The single ended design avoids the critical alignment required with two‐manifold systems.

ISSN:0034-6748    

DOI:10.1063/1.1683767

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A convection Pirani vacuum gauge covering the 1–1000 millibar range is described. It works in forced convection and Pirani modes for the high and low pressure ranges, respectively. Both effects combine in the intermediate zone. This gauge has been designed to be used with stratospheric balloons. Light weight, small power consumption, low temperature shift, and easy telemetering of information have been considered essential in the design.

ISSN:0034-6748    

DOI:10.1063/1.1683768

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A relative method for the measurement of gas viscosity is described. The method, similar to the Ostwald method for liquids, involves the comparison of flow times of various gases through a capillary flow meter. By this method the viscosity of perfluorobutene‐2 has been determined as 118.1 &mgr;P.

ISSN:0034-6748    

DOI:10.1063/1.1683769

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Commercially available magnetostrictive composites employ the differential magnetostriction exhibited by materials of different composition and are therefore sensitive to temperature changes as well as to variations in magnetic field intensity. In order to overcome this problem a new approach has been adopted, using laminas of the same material which yet possess different magnetostrictive characteristics. It is shown how, by suitable choice of material, the laminas can be prepared from highly textured polycrystalline sheets so that one lamina contains a high proportion of ⟨111⟩ crystal directions along its length while the other contains mostly ⟨100⟩ crystal directions along its length. Such laminas are found to exhibit different magnetostrictive coefficients and may be bonded together to form an effective magnetostrictive composite which is inherently insensitive to temperature change.

ISSN:0034-6748    

DOI:10.1063/1.1683770

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A double beam spectrophotometer has been developed which uses a logarithmic amplifier to obtain absorption coefficients and the area under absorption curves. The wavelength range is from 3000 Å to 2.3 &mgr; and resolution is determined by the grating monochromator to which the system is attached. With a resolution of 1 Å an absorption coefficient of 0.02 is easily measurable. The optical and electronic system of the instrument and its performance are described.

ISSN:0034-6748    

DOI:10.1063/1.1683771

出版商:AIP    

年代:1969

数据来源: AIP