摘要:

This paper is concerned with sensing devices that may be used for thermal monitoring and control of modern aircraft propulsion units. Performance and service requirements that transcend some aspects of present flight requirements for such devices are described. The possibility of exploiting the pneumatic probe and the high‐temperature thermocouple to these ends is explored. Summaries are presented reviewing recent progress in the technical development of high‐temperature measurement by these methods.Typical performance and thermoelectric behavior of twenty metallic thermocouples that have been calibrated above the melting point of platinum are presented. Seven of these pairs have been taken above 4000°F, and nine additional combinations have been calibrated above 3500°F. A comparison is made of the calibration atmospheres, maximum outputs, estimated maximum errors, temperature ranges of calibration, and ultimate temperature ranges for all thermocouples reported herein.A review of methods of, and properties of refractory oxides suitable for thermocouple protection at high temperatures are presented. A qualitative intercomparison of these materials is made by ranking them according to relative merit of features desirable for thermocouple protection and insulation in the subject application.

ISSN:0034-6748    

DOI:10.1063/1.1716061

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The method of investigating the magnetic anisotropy of single crystals by observing the torque exerted on a crystal by a homogeneous magnetic field was found to be subject to several sources of error which were of particular importance when small differences of susceptibility were involved. Several changes in design of the equipment and in the experimental procedure have been introduced, resulting in a great improvement in the reproducibility of the measurements; these changes included the introduction of effective draft shielding, the use of high magnetic fields to saturate ferromagnetic impurities, and the use of a graphical method of data analysis. The method of determining the torsion constants of thin quartz fibers from the period of oscillation of a torsion pendulum has also been investigated; for accurate values it is necessary that the oscillating pendulum be under high vacuum and shielded from static electricity. A slight decrease in the torsion constants of quartz fibers left under tension for long periods of time has been observed. A systematic method of mounting and orienting the crystal specimens has also been devised.

ISSN:0034-6748    

DOI:10.1063/1.1716062

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An electron‐bombardment detector developed for the detection of noncondensable as well as condensable molecular beams is described. The ionization efficiency for a hydrogen deuteride beam is in the range of 10−5to 10−4. Auxiliary components include: vacuum buffer chambers for source background gas reduction; a mass spectrometer for ion mass selection; an electron multiplier, electrometer, and phase‐sensitive detector combination for signal observation. Modulation techniques for beam and magnetic resonance detection are discussed. Efficiencies, background problems, and relevant noise sources are included in a discussion of operational characteristics. A resonance line trace produced by at most 3% of a total HD beam is presented to demonstrate the signal to noise ratio at low signal levels. The system has effectively detected beams of permanent gases such as HD, D2, and Ne.

ISSN:0034-6748    

DOI:10.1063/1.1716063

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Second‐order focusing properties are considered for a nonuniform magnetic field with arbitrary circular boundaries in the case of normal entry and exit. The formula obtained here agrees with that obtained by Hintenberger for the special case &agr;=&bgr;=0. It is also shown that the double and second‐order focusing can be achieved simultaneously. The numerical results are represented graphically for a symmetrical double‐focusing spectrometer with an arbitrary deflection angle.

ISSN:0034-6748    

DOI:10.1063/1.1716064

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A high‐speed spark light source is described which can be used in the photographic systems of shock tunnels, shock tubes, and ballistic ranges. The source provides five high‐intensity flashes, each with available delays of as low as 0.1 &mgr;sec between consecutive sparks. The transmission line principle is used with barium titanate capacitors to obtain a spark discharge time of under 0.1 &mgr;sec. Five spark assemblies are mounted in line with a lens system to provide a common point where all spark flashes are brought to focus. The light source is used in conjunction with a high‐speed drum camera on which is mounted the recording film.

ISSN:0034-6748    

DOI:10.1063/1.1716065

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The design, construction, and operation of a displacement detector are described. In the operation of the detector the frequency shifts of two oscillators are observed; these frequencies depend on the separation distance of two probe capacitor plates from a third ground plate that is common to both of them. The circuitry and mechanical arrangement are such that two independent outputs are obtained; one is proportional to displacement normal to a surface and the other is proportional to displacement tangential to the surface. The calibration and testing of the device are described, and results of these tests are given along with displacement observations made on waves in a concrete surface. The detector is sensitive with good signal‐to‐noise ratio for displacements as small as 10−2micron and with displacement frequencies as high as 105cps, two components simultaneously.

ISSN:0034-6748    

DOI:10.1063/1.1716066

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An apparatus having up to four Po210sources suitable for radiation chemistry studies in liquids is described. Each unit consists of a source and housing that supplies a collimated beam of &agr; particles, a variable speed stirrer, and an irradiation cell holder. Energy output is measured with the ferrous sulfate dosimeter.

ISSN:0034-6748    

DOI:10.1063/1.1716067

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A differential transformer with variable coupling placed at the tip of a catheter tube and surrounded by an umbrella type device has been used for the measurement of blood velocity. The instrument was carefully tested by means of a pump producing truly sinusoidal fluid movement. It was shown that the flowmeter has a linear characteristic and a linear frequency response with pump frequencies up to 25 cps. A blood flow recording taken in the ascending aorta of a dog with unopened chest demonstrates the instrument's practical application.

ISSN:0034-6748    

DOI:10.1063/1.1716068

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A new microscope mechanical object stage is described. In addition to the usual arrangements for measurements of thexandycoordinates for nuclear tracks in photographic emulsions, the stage is rotatable about the optical axis of the microscope as well as about an axis perpendicular to the optical axis. The angles of rotation can be read off scales. Through these arrangements and by the use of an eyepiece micrometer the orientation and the length of nuclear tracks can be measured directly.

ISSN:0034-6748    

DOI:10.1063/1.1716069

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An apparatus is described for measuring the ordinary Hall coefficient of ferromagnetic metals such as Ni and of ferrimagnetic semiconductors such as Fe3O4. An alternating electric field at 1000 cps is used with a static magnetic field. The apparatus has a sensitivity of 10−18watt, a noise level of 10−9volt, and a voltage resolution of one part in 105. The sensitivity is required by the small ordinary Hall coefficient of the metals and the ferrites, and the resolution is needed to separate the ordinary and extraordinary Hall effects. The apparatus may be used with sample impedances ranging from less than one ohm to several thousand ohms. The sample holders which are an important part of the apparatus are described. The measurement technique is detailed as is a method for ensuring the absence of spurious voltages. The system may also be used to measure changes in other second‐order effects by bucking out all first‐order effects.

ISSN:0034-6748    

DOI:10.1063/1.1716070

出版商:AIP    

年代:1958

数据来源: AIP