摘要:

Spectrometer measurements were made of the x‐ray diffraction peaks for cold‐worked filings of thoriated tungsten: 99.25 tungsten, 0.75 thoria. A Fourier analysis was made of the peak shapes, and the instrumental broadening corrected by using the peaks of annealed material. When the particle size and the distortion effects were separated, it was found that the particle size broadening corresponded to a sizeL¯=200A. This value is to be interpreted as the size of the coherently diffracting domains, and is a measure of the distance between layers of slip planes or layers of dislocations. The coherent distortion broadening indicated that strains in this material vary appreciably over distances of 25A or less. Strain distribution curves were obtained from a Fourier transform of the experimental coefficients. There is an indication that strains are smaller in the larger coherent regions. The measured root mean square strain corresponds to an elastic energy of 0.18 cal/g. Within experimental accuracy the integrated intensities are the same for the cold‐worked or the annealed samples.

ISSN:0021-8979    

DOI:10.1063/1.1721133

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

Equations are derived for the current induced in an infinitely long, thin, straight wire of nonzero surface impedance when the wire is connected to a flanged coaxial line. Also, radiation field patterns are computed and the input conductance determined. It is found that the current (and likewise the input conductance) can be separated into two components, one of which is a propagating or modal current. Graphs are presented from which the efficiency of excitation of the propagating current can be computed.A second structure consisting of a single wire between perfectly conducting parallel plates is solved as a boundary‐value problem. The solution is used in the discussion of the physical behavior of a finite single‐wire transmission line. In particular it is found that the usual transmission line concepts are valid under certain restricting conditions.

ISSN:0021-8979    

DOI:10.1063/1.1721134

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

Formulas for the electric field strength parallel to and perpendicular to the magnetic field for an idealized cyclotron dee system are derived by use of the Schwarz‐Christoffel transformation. A convenient method for computing numerical values for any geometry characterized by the ratio of dee gap to dee height is presented and applied.

ISSN:0021-8979    

DOI:10.1063/1.1721135

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

The mixed boundary value problem arising from the flow of current into a right circular cylinder of radiusathrough a perfectly conducting coaxial disk electrode at one end is solved approximately. The boundary conditions are met rigorously except that the electrode is not quite plane. A solution valid for all values of the disk radius is given for which in the worst case the deviation from flatness is nearly 0.01a. More exact solutions are worked out for disk radii ¼a, ½a, and ¾aand the first forty coefficients in the Bessel function series for the potential in the cylinder are tabulated. A cylinder whose diameter is eight times its length is also treated for disk radii ¼aand ½aand the first forty coefficients in the potential series are tabulated. The probable errors in the resistance formulas derived from these solutions are given.

ISSN:0021-8979    

DOI:10.1063/1.1721136

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

The electric charges created upon individual microscopic particles of an aerosol during its generation have been determined by the Hopper and Laby oil drop method. In the spraying of nonconducting liquids, the charges produced upon droplets in the diameter range 2–50 microns are found to follow a normal distribution with the average charge zero and the mean square charge proportional to droplet volume. This result favors the electrification mechanism of statistical fluctuation of electrolytic ion concentration among the droplets rather than the more prominent Lenard mechanism. The charge distribution among clean mercury droplets in the diameter range 1–6 microns sprayed from a glass sprayer is asymmetric because of contact effects at the mercury‐glass interface: the average droplet charge is positive, relatively large, and increases with droplet diameter. The dependence of dispersive dust charging upon particle surface roughness is illustrated by observations made with relatively smooth microscopic glass spheres and compared with data for rough crushed quartz particles.

ISSN:0021-8979    

DOI:10.1063/1.1721137

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

The dynamic Young's moduli and the internal friction of fused quartz, Pyrex glass, and soft glass rods were measured at a frequency of 37 kilocycles, in longitudinal vibration, within the temperature range −170° to 1000°C. The moduli of Pyrex and quartz increased with rising temperature, up to the softening point of the glass, while that of soft glass decreased. All three moduli were approximately linear with respect to the temperature over most of the measurement interval. Internal friction maxima were noted at high temperatures, while at the lowest measurement temperatures a significant increase in background damping occurred. A brief recapitulation of existing theory is given and employed to interpret the internal friction data. It is suggested that, in microscopically inhomogeneous media, the diffusion measurement by internal friction methods is not equivalent to the determination by other techniques.

ISSN:0021-8979    

DOI:10.1063/1.1721138

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

A time‐free recursion formula development for the classical radioactive decay leads to a distribution form of solution for both natural and artificial chains.

ISSN:0021-8979    

DOI:10.1063/1.1721139

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

The transfer of monolayers of proteins to solid surfaces from a liquid substrate is now a well‐established procedure. It has been found that if particulate matter is present in the protein solution from which the monolayer is to be formed, the surface streaming set up by the spreading of the protein over the surface of a liquid substrate causes the particles to be distributed uniformly throughout the available surface. They can then be transferred to a solid surface along with the protein monolayer. This procedure has been used in the preparation of specimens for electron microscopy by raising previously immersed collodion‐coated wire mesh screens, attached to glass microscope slides, through the interface occupied by the monolayer. Micrographs of viruses, bacteria, and other bodies mounted in this manner have been obtained. The method commends itself by virtue of the simplicity of the procedure, the uniform dispersion of the particles, the elimination of interference from extraneous dissolved substances, and the high quality of the micrographs obtained.

ISSN:0021-8979    

DOI:10.1063/1.1721140

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

The diffusion in the ground of a radioactive tracer gas, used for locating leaks in buried pipes, has been calculated, and the results are presented in the form of graphs. It is shown how the information can be used to obtain the amount of radioactivity needed in a test for both beta‐emitters (C‐14 in carbon monoxide) and gamma‐emitters (Br‐82 in methyl bromide).

ISSN:0021-8979    

DOI:10.1063/1.1721141

出版商:AIP    

年代:1953

数据来源: AIP

摘要:

This paper describes the use of an electromechanical analog to examine the limiting values of various parameters needed to destroy a predominantly subharmonic oscillation of order one‐third, existing in a nonlinear system. The results of the analog are then compared with the limiting values suggested by existing theory.

ISSN:0021-8979    

DOI:10.1063/1.1721142

出版商:AIP    

年代:1953

数据来源: AIP