摘要:

The LEED electron optics can be used as an electrostatic mirror microscope with resolution better than 5 &mgr; and magnification over 1000×. Defects in silicon picture tube‐diode arrays and scratches on sapphire substrates at which deposited aluminum had preferentially nucleated have been successfully imaged using LEED optics with no modifications. This method can be used to investigate surface topography and electric and magnetic field variations.

ISSN:0034-6748    

DOI:10.1063/1.1685041

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

An equipment has been developed for in‐cell determination of Young's modulus of irradiated materials in a continuous manner in the 20–1000°C temperature range. Longitudinal vibrations are electrostatically induced and maintained in the sample at its resonance frequency. The equipment has been used to check U‐C nuclear fuel samples and alloy specimens.

ISSN:0034-6748    

DOI:10.1063/1.1685042

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A system has been developed which allows spin wave thresholds in ferromagnetic materials to be determined extremely rapidly. Curves of the change in cavity reflection coefficient as a function of the microwave field amplitude are generated on an X‐Y recorder. The thresholds are read directly off the calibrated recorder plot.

ISSN:0034-6748    

DOI:10.1063/1.1685043

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A new type of dilatometer has been built to measure the strain induced in crystals, for example, by irradiation. The instrument uses high angle diffraction to obtain large lattice dispersion, and the parallel crystal configuration to achieve low wavelength dispersion. It is not necessary to know the wavelength of the x rays nor the order of diffraction and the measurement of strain is reduced to the measurement of an angle. Strains of 1×10−5may be measured with error less than 5%. The paper discussed the theory, design, and accuracy of the instrument and presents typical experimental results.

ISSN:0034-6748    

DOI:10.1063/1.1685044

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The instrumentation, the design of the free‐space focused microwave bridge system, and the technique for determining the complex permittivity of materials from ambient to 2500°C are described. The system employs a rotating disk sample which is located at the coincident focal point between two prolate spheroidal reflectors; the sample is heated on one side by oxyacetylene flames in such a manner that the microwave beam is not affected by the flames. Dynamic measurements are made of the sample insertion phase and insertion loss. A transient heat conduction analysis is used to determine the temperature profiles within the sample, and the electrical transmission data are correlated with the temperature profiles to give dielectric constant and loss tangent as functions of temperature. The relative dielectric constant and loss tangent of high purity slip‐cast fused silica (density of 1.91 g/cm3) are determined to 2500°C. The relative dielectric constant vs temperature function is a segmented line and is 3.34 at ambient, increases linearly with temperature to 3.54 at 1500°C, 3.98 at 1600°C, 4.18 at 1700°C, and 4.32 at 2500°C. The loss tangent vs temperature function is also a segmented straight line when plotted on semilog paper with a value of 0.0005 at ambient and 0.09 at 2500°C.

ISSN:0034-6748    

DOI:10.1063/1.1685045

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

An instrument is described that performs the following timing functions: (a) selection of time intervals which lie within a preselected range; (b) upon occurrence of a selected time interval, generation of three real time triggers, two of which are delayed by separately adjustable multiples of the time interval and one of which coincides with the end of the interval. Function (b) is especially valuable in time coincidence work with poorly analyzed beams or with particles of indeterminate and widely varying velocity; an example of this type of application is discussed. Circuit values are given for a unit with time interval limits continuously variable within 1–10, 10–100, and 100–1000 &mgr;sec ranges and with time interval multiplying factors continuously variable from 0.1 to 1 or from 1 to 10; design equations are presented to facilitate modification of these values, as may be required for other applications.

ISSN:0034-6748    

DOI:10.1063/1.1685046

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A new cylindrical retarding potential difference type or energy modulated electron spectrometer has been constructed with high energy resolution. For energies greater than 1 eV the ratio of beam currentIto energy spread FWHM, &Dgr;Ehas been found to be approximately constant so thatI/&Dgr;E≃10−7(A/eV) at about 20 eV. For electron energies from 0 to 1 eV the electron current increases with energy by about 10−7A/eV for &Dgr;E≃0.1 eV to the value given by the above expression. For energies above 1 eV the electron current is a very slowly varying function of energy. The energy resolution has been checked to 0.008 eV by studying the shape of the He−(2S½) resonance at 19.3 eV in a transmission experiment. The over‐all performance of the spectrometer has been studied for electron energies from 0 to 60 eV in transmission experiments in He by studying structures in the electron scattering cross section.

ISSN:0034-6748    

DOI:10.1063/1.1685047

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A method is described for the accurate calibration of electron microscope tilting holders. Diffraction patterns taken from a specimen as it is tilted can be accurately analyzed and used to calibrate the tilt angle and axis of the holder. The method is applied to a test of the double tilt holder of a Philips EM300. The tilt axis is shown to change by about 8° as the specimen is tilted from −30 to +30°.

ISSN:0034-6748    

DOI:10.1063/1.1685048

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The dielectric constant and loss of a liquid dielectric are determined from measurements of the input impedance of a coaxial cell terminated with a short circuit. The location of the short circuit is continuously variable over a range of 2.5 cm to allow selection of the optimum sample length. Dielectric constants from 1 to 100 with high or low loss have been measured in the frequency range 300–9000 MHz using the General Radio type 900LB slotted line.

ISSN:0034-6748    

DOI:10.1063/1.1685049

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

This paper reports in detail the design and construction of a new scattered light polariscope for three‐dimensional birefringent flow research. The unique features of this polariscope, which were employed to overcome the particular problems associated with birefringent flow analysis using scattered light, are pointed out. A photograph of typical birefringence patterns obtainable is shown. A comparison of theoretical and experimental results for a particular flow case is made indicating the accuracy that can be obtained using this polariscope.

ISSN:0034-6748    

DOI:10.1063/1.1685050

出版商:AIP    

年代:1971

数据来源: AIP