摘要:

Equipment has been constructed for experimentation at very high pressures and temperatures. With the modified Bridgman anvil device described, it has proven possible to maintain pressures in excess of 100 000 atm simultaneously with temperatures above 3000°C for periods greater than one hour. [The fixed points used to infer this pressure are taken to be the pressure values established by Bridgman for discontinuities of the electrical resistance of bismuth and barium, 25 650 kg cm−2and 80 000 kg cm−2, respectively, and called the bismuth and barium points. Recent unpublished work indicates that the barium point pressure will probably have to be revised downward materially, reducing our pressure estimates in the upper range.] The use of an extrudable plastic compressible gasket is described. Several considerations are presented concerning the support of high pressure components constructed of cemented tungsten carbide. Coesite, almandite, and diamond have been synthesized in the apparatus.

ISSN:0034-6748    

DOI:10.1063/1.1717550

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Bulk samples of germanium have been reduced to sections thin enough for transmission electron microscopy. The apparatus and techniques of this virtual‐electrode electrolytic etching process are described in detail with emphasis on the geometric control obtained. An example is given of an electron transmission micrograph of a 500‐A‐thick section.

ISSN:0034-6748    

DOI:10.1063/1.1717551

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The construction of a bipolar oxygen sensitive polarographic microelectrode is described. A platinum wire serves as the active electrode and the reference electrode is a gold plate on an indium‐tin base. The electrode has an outside diameter of approximately 70 &mgr;. It is sturdy, electrically stable, highly sensitive to changes in oxygen concentration, and is nontoxic to animal tissue.

ISSN:0034-6748    

DOI:10.1063/1.1717552

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The time‐to‐amplitude converter is designed for time measurements in the 10−7to 10−11sec range. The time resolution of the system is defined as the full width at half maximum of the amplitude distribution produced by the time converter in response to prompt coincidence events. The best time resolution obtained was 4.7×10−10sec. The time converter and all of the accessory circuits are described.

ISSN:0034-6748    

DOI:10.1063/1.1717553

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

An electronegative gas detector has been developed which is capable of measuring one part of SF6in 107parts of air. The operation of the instrument is based on the differences between various electronegative gases in the rates of electron attachment at low electron energies, and on the differences of mobilities of the resulting negative ions in an electric field. The instrument operates at atmospheric pressure (E/p∼1 v/cm‐mm Hg) and uses a modulated ultraviolet light source to produce at a photocathode pulses of photoelectrons which are attached to produce negative ions. The differences in cathode‐anode transit times of the negative ions result in different phase shifts of the observed cathode current. The measured phase shifts serve to indicate the amount of electronegative gas present.

ISSN:0034-6748    

DOI:10.1063/1.1717554

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The limitation in the null instrument sensitivity of bridges leads to errors which are due to the uncertainty in the null adjustment. This paper deals with this sensitivity error in Wien frequency bridges. Formulas for the relative error in frequency measurement and for optimum bridge parameters are derived. The influence of deviations from the optimum parameters is shown and discussed. It is shown that, for bridges covering a wide frequency range, certain free parameters should be made adjustable to maintain good sensitivity.

ISSN:0034-6748    

DOI:10.1063/1.1717555

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A high temperature, high vacuum diffractometer camera, which fits the Norelco Wide Range Goniometer, has been designed. The construction details of the camera are presented.

ISSN:0034-6748    

DOI:10.1063/1.1717556

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

To design a minimum noise figure tunnel diode rf amplifier, the point of minimumI/|Gd| ratio must be known. Also of importance in the design are the diode bias current required at this point of minimumI/|Gd| ratio and the conductance obtained at this bias point. Described in this paper is a scheme whereby X‐Y recordings of theI‐V, G‐V, andI/G‐Vcurves for a tunnel diode can be obtained.

ISSN:0034-6748    

DOI:10.1063/1.1717557

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Two simple methods of using photographic emulsions as a means of determining the size spectrum of water drops are described. The methods are sensitive to droplets 80 &mgr; or greater in diameter; one enjoys the advantage of requiring no advanced preparation of materials, the other provides a permanent record. The procedures were developed to obtain raindrop size distributions but may be applied equally well to problems concerning drop spectrums from spray systems.

ISSN:0034-6748    

DOI:10.1063/1.1717558

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

An account is given of a drop generator in the form of a rotating Plexiglas bowl which dispenses large quantities of uniform drops (80–400 &mgr;) with excellent selectivity as to drop diameter.

ISSN:0034-6748    

DOI:10.1063/1.1717559

出版商:AIP    

年代:1961

数据来源: AIP