摘要:

A helium‐neon maser of the plane parallel Fabry‐Perot type has been constructed in which both the angular adjustments and the plate separation may be controlled through magnetostrictively produced distortion in a rigid Nilvar mounting frame. The maser has been designed with the eventual use of negative feedback frequency stabilization in mind. Orthogonality is maintained in both angular coordinates over a range of about 15″ and the maser has been found to remain within these limits over many days of continuous operation under normal laboratory conditions. Two methods of operation are described : the first permits simultaneous and independent adjustment of both the plate angular alignment and the plate separation. The second method, though requiring less auxiliary equipment, only permits control over the two angular coordinates. Some of the mechanical design considerations and construction details are also discussed. It is felt that the present interferometer design is considerably less susceptible to mechanical instability than others reported to date.

ISSN:0034-6748    

DOI:10.1063/1.1746612

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A low pressure spark gap switch suitable for use as a main switch and as a ``crowbar'' switch on a capacitor bank is described. The switch has been operated over a voltage range of 0.5 to 25 kV, at energies up to 4 kJ and currents up to 500 kA. Under normal operating conditions the triggering time is 40 nsec and the jitter approximately 10 nsec. The inductance of the main switch is 4 m&mgr;H and the inductance of the crowbar switch is about 1 m&mgr;H.

ISSN:0034-6748    

DOI:10.1063/1.1746614

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A dc bridge circuit for the comparison of three four‐terminal resistors is described. It is an extension of the Kelvin double bridge arrangement, which, effectively, enables four‐terminal resistors to be connected in series. The bridge is used for the direct measurement of the sum or difference of two low resistances in terms of a standard. The exact balance equation is quite complicated, but can be approximated with excellent accuracy byX1/A+X2/B—X3/C=0, whereX1,X2, andX3are the four‐terminal low resistances, andA, B,andCare large resistances.

ISSN:0034-6748    

DOI:10.1063/1.1746616

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Alternating magnetic fields in the range of 2800 to 4300 G are measured in terms of the frequency of the free‐electron spin resonance in 1:1‐diphenyl‐2‐picryl hydrazyl. The probe is constructed entirely of dielectric materials. An accuracy of 0.1% in the field determination was obtained.

ISSN:0034-6748    

DOI:10.1063/1.1746619

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A spectrometer that utilizes rollers rather than gears to perform the appropriate angular changes of its components has been designed and put into operation. The precision ground rollers proved to be effective in reducing any backlash in the drive mechanism without introducing any noticeable skidding. A set of screws provides a simple and rapid way of securing the diffraction crystal in its proper place for continuous alignment.

ISSN:0034-6748    

DOI:10.1063/1.1746621

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A liquid metal solution calorimeter and its operation are described. The method of calculation is outlined and the sources of error are analyzed. In this calorimeter, heat effects upon dissolution of samples in liquid metals are measured; heats of solution are determined directly and heats of formation, energies of ordering, and the stored energy of cold work are found by a difference method. The calorimeter operates in the temperature range 240 to 450°C; samples are added from 0 or −195°C. Highest accuracy, of the order of ±2 cal/g‐atom, is attained with suitably chosen solute‐solvent combinations giving very small total heat effects upon dissolution.

ISSN:0034-6748    

DOI:10.1063/1.1746623

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A shock tube for studying problems in rarefied gasdynamics is described. The motivation for operating at low density (to increase the length and time scales of certain interesting flows) and the effect of low density on the performance and design of the shock tube are discussed. In order to guarantee uniform and reproducible shock waves of moderate strength, the configuration of the tube is conventional. However, innovations are introduced (for example in the suspension, the pumping system, and the diaphragm loading and rupturing mechanism) to simplify the operation of the large facility. Care in the design of the tube as a vacuum system has resulted in a leak rate of less than 0.01 &mgr; Hg per hour. A series of shakedown runs at relatively high pressures has shown, for example, that the reproducibility of a given shock Mach number is ±0.6%.

ISSN:0034-6748    

DOI:10.1063/1.1746625

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A cw acoustic spectrometer operating in the frequency range of 10 to 1000 Mc is described. The acoustic probe, applicable to low temperature measurements, is characterized by its mechanical resonance properties. Several of the novel features of the spectrometer are described in some detail. The apparatus, essentially the acoustic analog of an electron paramagnetic resonance microwave transmission spectrometer, has been applied to the study of electron spin‐phonon interactions in solids.

ISSN:0034-6748    

DOI:10.1063/1.1746628

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A high temperature drop calorimeter to measure heat contents between 1000 and 2500°C was made. A graphite tube furnace and an adiabatic shielded receiver block are described. The receiver block was electrically calibrated and the calibration compared with the heat content of &agr;‐aluminum oxide.

ISSN:0034-6748    

DOI:10.1063/1.1746630

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A practical, dual‐channel, multicolor oscilloscope has resulted from NRL research on transparent cathodoluminescent screens. A transparent multicolor screen is used with a conventional cathode‐ray tube in an NRL modified commercial dual‐channel oscilloscope. An inherent advantage of this oscilloscope over the conventional one is the apparent ease of monitoring two or more channels simultaneously without the possibility of error. Another advantage is that it maintains sharp distinct patterns under adverse light conditions.

ISSN:0034-6748    

DOI:10.1063/1.1746632

出版商:AIP    

年代:1962

数据来源: AIP