摘要:

A series of improvements in electric shock tube drivers is described, comprising a segmented series discharge driver for long duration flows, a segmented parallel discharge driver for large diameter shock tubes, a switchless shock tube for maximum circuit efficiency, and a metal walled driver for radiant energy conservation.

ISSN:0034-6748    

DOI:10.1063/1.1720247

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

An electronic instrument able to trace on a X‐Y recorder all types of magnetic curves of ferromagnetic materials and having better performance than ordinary ballistic equipments is described. The main features of the instrument are (a) the ability to trace any magnetic curve keeping the induction flux derivative constant, which minimizes the errors due to eddy currents in the specimen, and (b) the extremely low drift of the integrating circuit, which allows it to trace hysteresis loops of specimens of normal dimensions in times as long as 30 min, yet maintaining the accuracy within 1%. Sensitivity, accuracy, errors due to eddy currents, and comparison with ordinary ballistic methods are discussed in detail in the text. Many experimental results are also given.

ISSN:0034-6748    

DOI:10.1063/1.1720248

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A new mechanical device is described which rapidly yields the derivative of a data curve in the form of a continuous plot. This table top differentiator, the operation of which is mostly manual, depends in principle upon the measurement of the slope of successive tangents to the curve. Slopes of numerical values between −1 and 5 are measured conveniently. The device has been applied to the differentiation of interference patterns from the analytical ultracentrifuge.

ISSN:0034-6748    

DOI:10.1063/1.1720249

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The processes of electron multiplication and electron loading in acceleration tubes have been investigated theoretically. These effects limit the maximum voltage at which Van de Graaff generators can operate. A new design for an accelerating tube is proposed which by virtue of its closely spaced electrodes has the advantage of ease of calculation and flexibility of boundary condition. Computer calculations were done for this tube to study electron multiplication trajectories. We have found that an axial alternating electrical field gradient can limit such avalanches by periodically trapping the electrons.

ISSN:0034-6748    

DOI:10.1063/1.1720250

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A technique is described whereby the writing rate of a rotating mirror streak camera can be determined with the use of a pulsed laser and a knowledge of the speed of light. The result of using the technique to calibrate a 35 mm streak camera is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1720251

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A refrigerated mass spectrometer inlet apparatus is described which also functions as a multipurpose low temperature reactor and a rough separative device. The arrangement has proven to be a powerful tool in the study of the synthesis, reactivity, and energetics of compounds that are stable only at very low temperatures.

ISSN:0034-6748    

DOI:10.1063/1.1720252

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A method is outlined to plot the dependence of the critical field of a superconductor on its critical current automatically on the screen of an oscilloscope. Critical field and current, respectively, control the X and Y input of the oscilloscope whereas the beam intensity is controlled by the voltage drop across the superconductor. Use of short current and field pulses eliminates disturbing thermal effects. The device is particularly useful for routine measurements on cryotron circuits.

ISSN:0034-6748    

DOI:10.1063/1.1720253

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Equations are developed for designing hydraulic rams of maximum thrust for a given external cylinder diameter. For push type rams, the optimum ratio of outside to inside wall diameterwis 1.554, and the maximum fluid pressurePto be used is 0.4142 times the allowable hoop stressftin the cylinder. For pull type rams in which the allowable tensile stressfbin the pull bar (cylinder rod) and the allowable hoop stressftin the cylinder wall are equal,w=1.414 andP=0.333ft. When these allowable stresses are not equal, more complicated relationships exist and are discussed in the text.

ISSN:0034-6748    

DOI:10.1063/1.1720254

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

An apparatus for simultaneously measuring the time dependence of (a) ion densities, (b) metastable atom densities, and (c) the intensities of spectral lines and bands during the decay period of a gaseous plasma is described. It is comprised of a quadrupole mass spectrometer for the ion density measurements and a light spectrometer for light emission and fractional light absorption studies. The reliability of the results obtained by mass spectrometer probing of a decaying plasma was checked by comparing the results obtained in helium with those obtained by other measuring methods. The data were found to be consistent and showed that this technique can be a significant tool for the study of collision processes occurring in decaying plasmas. Moreover, the simultaneous application of mass and light spectrometric methods gives information about the time dependences of the various plasma constituents at the same plasma region.

ISSN:0034-6748    

DOI:10.1063/1.1720255

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Several different high explosive driven shock tubes have been developed as sources of short duration, supersonic, high pressure pulses which can be used to load large, massive objects with accelerations up to many thousandg's. These shock tubes are particularly appropriate for simulating strong blast effects on hardened structures. An important characteristic of these shock tubes is the use of detonation products as the primary working fluid. Therefore, this represents one of the few instances in which the ``cold flow'' of a shock tube has been used for aerodynamic testing. Extensive design calculations are presented, and experimental measurements in a number of configurations are in good agreement with the calculations. The facilities tested have produced peak dynamic pressures of 70 to 2000 bar for half‐time durations from a few hundred microseconds to several milliseconds. Tube diameters have varied from 0.6 to 2 m, and the lengths have ranged between 3 and 15 m. All of the shock tubes are, at least in part, expendable. However, they can be quickly constructed to meet given flow requirements at costs quite modest when compared with those of competitive techniques for producing high accelerations of large objects.

ISSN:0034-6748    

DOI:10.1063/1.1720256

出版商:AIP    

年代:1966

数据来源: AIP