摘要:

A technique for external selection of a single pulse from the output train of a mode locked ruby laser is presented. Ease of optical alignment and the ability to be triggered by a small individual pulse early in the train are the chief advantages of this photodetector technique over that of spark gap triggering.

ISSN:0034-6748    

DOI:10.1063/1.1684422

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A room temperature supersonic nozzle source beam was constructed as the target for a shock tube driven molecular beam. It is actuated electropneumatically and provides a few hundred microseconds of nearly constant intensity. The beam is formed from a supersonic flow by a two‐stage skimming process. In optimizing the configuration of skimmers and nozzle it was found that viscous regions in the system could be detected by observing the transient flux in the peripheral region around the beam.

ISSN:0034-6748    

DOI:10.1063/1.1684423

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A pinhole camera system giving time resolved photographs of the x‐ray source in an intense plasma discharge is described. Each pinhole projected an image of the x‐ray source onto a sheet of scintillation plastic which converted the x rays into a visible light image that was photographed with an image convertor camera. Use of twin pinholes with appropriate filters and scintillator thicknesses provided some spectral resolution. A spatial resolution of 2 mm was achieved with a time resolution of 10 nsec.

ISSN:0034-6748    

DOI:10.1063/1.1684424

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The general need for an inexpensive sensor of plane coordinates has been satisfied by devising a simple electrical method. Two orthogonal sheets of conducting paper are connected in such a way thatxandycoordinates appear as independent dc potentials. For example, one may wish to process graphical information,y(x), by reading digitizedxandycoordinates, by replotting a functiony(x), or by feedingy(x) into a computer. These operations and others are performed by using the plane coordinate sensor with existing electronic systems.

ISSN:0034-6748    

DOI:10.1063/1.1684425

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

This paper describes a simple computer program which calculates the magnetic fieldBinside the bore of any system of coaxial uniform current density solenoid of rectangular cross section using Garrett's method [J. Appl Phys.22, 1091 (1951)]. Two versions of the program exist, the first in the Dartmouth form of the language BASIC, the second in the language FORTRAN IV. Both versions are ideally suited to modern digital computers, including time shared computers. Copies or listings of the programs are available upon request. The programs are based on those used to design a miniature superconducting magnet for dip experiments.

ISSN:0034-6748    

DOI:10.1063/1.1684426

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An accurate method for measuring the amplitudes of sinusoidal ripples using the intersection of caustic surfaces has already been developed. By comparison with the sinusoidal case, we find that the same equations for the amplitudes apply to damped spreading ripples, for example, those produced by a small spherical source in a real liquid. The limitations on the ratio of the spatial absorption coefficient to the wave number and on the distance from the point source are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1684427

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Chemical and electrochemical polishing methods which allow submicroscopically smooth optically flat surfaces to be produced on crystals of copper and copper alloys are described. This is made possible by the use of solutions for cloth chemical polishing which have as additives nitrogen‐containing mercapto‐sulfur compounds and surface active agents, which facilitate rapid flattening of the surfaces. Conditions for producing surfaces with the best compromise between flatness and submicroscopic smoothness have been worked out. A new system in which an endless cotton belt, saturated with a phosphoric acid electrolyte containing chromic acid, moves between a stationary cathode and the stationary anodic specimen has been introduced for electrochemical finishing. This almost eliminates the fine grained structure often seen on electropolished surfaces of alloy crystals.

ISSN:0034-6748    

DOI:10.1063/1.1684428

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The coefficient of thermal expansion of a fluid can be measured by determining the critical temperature difference for the onset of thermal convection in a fluid layer heated from below. This method is particularly useful for fluids of very low thermal expansion because its accuracy is independent of the magnitude of the thermal expansion. It is easily adapted to measurement at elevated pressures. Accuracy of 0.5% is obtainable with care.

ISSN:0034-6748    

DOI:10.1063/1.1684429

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A Lloyd mirror laser interferometer is described which determines the refractive index gradient in a diffusion layer. The interference fringe movement is detected by an array of n‐p‐n planar silicon photodevices the output of which is recorded by oscillographs. Various modes of measurement are discussed which are suitable for transparent or opaque electrodes. The presently used measuring mode is based on the determination of the reflected ray's optical path length change at various angles of incidence. The refractive index gradient is obtained by an iterative solution of the derived equation for the optical path length change on a digital computer. The time dependence of the fringe movement during electrodeposition from CuSO4solutions is discussed in addition to the effect of incidence angle and cathode displacement. The use of this interferometer is not limited to electrochemical processes and it can be used for the study of refractive index gradients in heat and other mass transfer boundary layers at solids.

ISSN:0034-6748    

DOI:10.1063/1.1684430

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A high pressure nitrogen flash lamp is described which has a half‐height width of less than 200 nsec and a light output of more than 5×1014quanta/pulse.

ISSN:0034-6748    

DOI:10.1063/1.1684431

出版商:AIP    

年代:1970

数据来源: AIP