摘要:

A magnetometer was developed which utilizes a superconducting quantum interference device (SQUID) as a sensor, and permits digital and analog measurements of magnetic fields. The digital mode permits measurement of large field changes with a constant accuracy of approximately 1/10 the natural periodicity of a SQUID. (The natural period is typically 10−6–10−3G.) Thus, the precision of measurement of large field changes is high. The analog mode is advantageous for high precision measurement, of the order of 10−8G, but for small field changes. Combined mode measurements permit the very high precision of the analog mode to be combined with the large range of the digital mode. The digital mode, which represents an improvement over the original lock‐on magnetometer, utilizes two synchronous detectors to provide signals which uniquely determine the instantaneous magnetic bias of the SQUID. The synchronous detector outputs drive a novel logic circuit which produces appropriate add‐subtract pulses to a digital counter, which reads out field changes in units equal to the periodicity of a SQUID.

ISSN:0034-6748    

DOI:10.1063/1.1771358

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The sensitive time of a thin gap spark chamber immersed in a magnetic field was measured. The magnetic field was normal to the electric field of the chamber, and various amounts of Freon 12 (CCl2F2) were used to decrease the sensitive time. A concentration of 100 ppm Freon 12 was sufficient to make the sensitive time less than ½ &mgr;sec, with an efficiency of greater than 70% for delays of less than 300 nsec.

ISSN:0034-6748    

DOI:10.1063/1.1771359

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The apparatus and technique for preparing thin sections of nonmetals suitable for transmission electron microscopy are described. The last stage of the thinning process involves bombardment with argon ions. The optimum operating conditions of the discharge tube were established for near stoichiometric rutile (TiO2), and the quality of the sections evaluated by observation at 100 kV in an electron microscope. Specimens having (001), (110), and (100) surfaces were successfully prepared, and no damage was in evidence as a result of the nature of the preparation. It is believed the technique can be extended to the preparation of thin sections suitable for transmission electron microscopy of metals, as well as other nonmetals.

ISSN:0034-6748    

DOI:10.1063/1.1771360

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A means is described for remotely selecting one of four sources of gas for an rf ion source. The system consists of a specially designed five way ball valve connecting one of the gas sources to the ion source via a mechanical leak assembly. Provision is made for feedline roughout during source switchover.

ISSN:0034-6748    

DOI:10.1063/1.1771361

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A thermocell consisting of a rotating disk electrode and another wire electrode in an electrolytic solution is described. The temperature difference is produced by mounting a heater inside the rotating disk electrode while the temperature of the bulk solution is kept constant at a mean temperature of 21°C. The change of the thermoelectric power &egr; for 0.1 and 1.0 N aqueous KCl solution with Ag/AgCl electrodes was independent of the speed of rotation below 375–400 rpm (laminar flow range). At speeds >400 rpm, the &egr; values became dependent on the rotation speed, presumably because of increasing turbulence of the liquid. In the laminar flow range, the mean &egr; values were 185 &mgr;V/deg and 250 &mgr;V/deg for 1.0 N and 0.1 N aqueous KCl solutions, respectively.

ISSN:0034-6748    

DOI:10.1063/1.1771362

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A method is described for obtaining optical spectra of solids subjected to short duration pulsed magnetic fields of the order of 300 kOe. A spectral region is scanned repetitively every 28 &mgr;sec by a moving slit and detected photo‐electrically, making it possible to measure wavelength and intensity changes of spectral features as a function of magnetic field. Provision is made for cooling the sample to liquid helium temperature. The Zeeman effect of the7F0−5D2transition of3+Eu in europium tungstate is used as a demonstration of the technique.

ISSN:0034-6748    

DOI:10.1063/1.1771363

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A simple and sensitive method has been devised for measuring the pressure dependence of the thermal conductivity of gases. The method uses the high thermoelectric power of a semiconductor for the accurate measurement of a temperature difference. Data at 25°C for argon, nitrogen, and helium to 3000 atm and carbon dioxide to 1300 atm are given. The results are compared with those of other investigators and agreement is generally better than 10%, using a two point calibration, and better than 3% using a multipoint calibration.

ISSN:0034-6748    

DOI:10.1063/1.1771364

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

This paper describes an instrument capable of measuring the roundness of an object with a resolution of 5 m&mgr;. The instrument consists of a precision spindle with hydrostatic fluid bearings and a capacitance displacement transducer. In this scheme, the displacement transducer is part of a capacitance bridge, which is made self balancing by closing the servo loop to the nulling capacitor through the recorder pen motor. Also, an instrument using a multiple beam interferometer for the displacement transducer calibration is briefly described.

ISSN:0034-6748    

DOI:10.1063/1.1771365

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A Faraday effect optical isolator was constructed for the infrared region. The nonreciprocal element of the isolator was a lead glass rod in the magnetic field of a solenoid. A triple pass of the light beam through the glass decreased the magnetic field strength required for a 45° Faraday rotation. For 1.062 &mgr;, the isolator had a 1.4 dB insertion loss, and a 29 dB isolation. Slight optical imperfections in the isolator components limited the isolator operation.

ISSN:0034-6748    

DOI:10.1063/1.1771366

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A new plasma source is described. A collimated beam of photons of 6 &mgr;sec duration generates a plasma by single quantum photoionization of a rarefied gas. A uniform plasma column with sharply defined initial boundaries is produced remote from the container walls and in the absence of currents or fields. At 90 cm from the photon source, plasma densities of 1010cm3are produced in argon at a pressure of 5 &mgr;.

ISSN:0034-6748    

DOI:10.1063/1.1771367

出版商:AIP    

年代:1967

数据来源: AIP