摘要:

A simple circuit is described which provides a fixed output amplitude for an input variation of 20 dB and with a relative phase shift variation (output versus input) of only 0.12° over the same range. The circuit was developed for use in a heterodyne holographic interferometry system where relative phase measurements to an accuracy of 0.36° are required of signals whose amplitudes may vary by as much as an order of magnitude during a single experiment.

ISSN:0034-6748    

DOI:10.1063/1.1138564

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A novel method of mounting thin samples for electrical measurements is described. A vacuum chuck holds a ceramic mounting plate, which, in turn, holds the sample. Contacts on the mounting plate establish electrical connection to the sample. The attachment of wires directly to the sample is unnecessary.

ISSN:0034-6748    

DOI:10.1063/1.1138565

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The application of chemical thermodynamics to the design of long‐life, high‐temperature devices is advocated and illustrated by its use in selecting the material components for a high‐temperature lead vapor Raman cell. It is shown that the reduction of alumina and of a calcia–alumina sealing frit by tantalum lead to equilibrium aluminum and calcium partial pressures orders of magnitude greater than those over pure alumina at the desired cell operating temperature.

ISSN:0034-6748    

DOI:10.1063/1.1138566

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A low‐noise preamplifier circuit for use with Halltron HR‐66 Hall effect probes in the frequency range dc to 100 kHz, shows a wideband noise of 6‐ and 2‐mG rms for bandwidths of dc to 100 kHz and dc to 100 Hz, respectively. Below 100 Hz the noise is due to the 1/fnoise from the Hall probe, while white preamplifier noise dominates above 100 Hz. Above 1 kHz, preamplifier noise exceeds the noise of the Hall probe alone by a factor of five. dc drift of the system is approximately 10 mG in 24 h.

ISSN:0034-6748    

DOI:10.1063/1.1138567

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A computer‐controlled system for measuring bulk resistivity of insulating solids as a function of temperature is described. The measuring circuit is a modification of that given in the ASTM standard D257‐66, to allow for a number of operations during the data‐acquisition cycle. The bulk resistivity of an acceptor‐doped morphotropic lead zirconate–titanate piezoelectric composition has been measured over the temperature range +40 to +200 °C. The activation energy derived from the experimental data is compared to the published values of similar morphotropic compositions.

ISSN:0034-6748    

DOI:10.1063/1.1138568

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A circuit has been developed for the measurement of the electrical characteristics of devices sensitive to extrinsic noise and intrinsic power‐supply transients. The circuit comprises two active current sources running in opposition. The current can be ramped smoothly through current excursions of a maximum of ±1 A. Provision is also made for the modulation of the dc current output by an external ac source.

ISSN:0034-6748    

DOI:10.1063/1.1138569

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A simple and rapid determination of the saturation magnetizationMsof thin magnetic films is achieved by measuring with a precision balance the force exerted on the film when it is saturated by a field that lies on its plane and varies with a constant gradient along it. This field is obtained with Faraday pole tips for which the exciting coils are connected in opposition.

ISSN:0034-6748    

DOI:10.1063/1.1138570

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A new flow tube which was designed for O2(1&Dgr;)+metal vapor experiments is described. The combination of the tube with a metal vapor furnace solved two major problems in the experimental system: (a) it prolonged the time available for data collection from 1 to 60 h and (b) furnace outlet clogging has been eliminated.

ISSN:0034-6748    

DOI:10.1063/1.1138571

出版商:AIP    

年代:1986

数据来源: AIP