摘要:

The causes and results of inhomogeneous phase on oscillatory magnetization are considered and methods for determining experimentally whether phase inhomogeneity is producing significant deviations from the Lifshitz‐Kosevich theory are discussed. General expressions are derived for (i) the reduction in oscillation amplitude and (ii) the relative phase shifts between harmonics which result from inhomogeneous phase. For the specific case of a parabolic field distribution, several universal curves are given for estimating the size of field inhomogeneity effects as a function of the magnetic field strength and of the sample position along the field axis. The effects on the measured values of the collision parameter and absolute amplitude are also considered and these effects are illustrated by experimental results from oscillatory magnetization and magnetostriction measurements.

ISSN:0034-6748    

DOI:10.1063/1.1686386

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Measurement of temperature using a thermocouple or any other device requires a certain length of time. This time interval is of the order of magnitude of the thermal time constant of the measuring device. Here we describe an electronic circuit which makes the temperature measurement ``instantaneous.'' This is accomplished by combining the temperature at any instant with the rate of change of temperature. Thus the only limiting factor becomes the electronic time constant of the circuits involved. We have used our device in absolute measurement of optical power and have found that the typical time necessary for a temperature measurement can easily be 10–3× the thermal time constant of the measuring device.

ISSN:0034-6748    

DOI:10.1063/1.1686387

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A fully analytical study of the properties of the parallel plate electrostatic spectrograph in the relativistic region is presented. The formalism used allows for an exact tridimensional treatment whereby the coupling between the polar angles &thgr;, &phgr; appears through the quantity &agr; = −d&phgr;/d&thgr;only while the explicit expression of &agr;(&thgr;, &phgr;) remains unspecified. This freedom in the choice of the relationship &phgr; =f(&thgr;) may be used to improve on the properties of the instrument. The main consequence of the relativistic effect is to alter the shape of the focal surface in a way which reduces the versatility of the instrument when changes in energy range are considered. This stems from the dependence of &thgr;, &phgr; on &bgr; =v/cintroduced by the second order focusing condition. It is shown that versatility is restored to a considerable extent for suitable choices of &phgr; =f(&thgr;). The relative merits of various choices are discussed. A numerical calculation of the basic parameters of a spectrograph suited for astrophysical research is given stressing the possibility of flying such an instrument aboard a Space Shuttle within the Post Apollo program.

ISSN:0034-6748    

DOI:10.1063/1.1686388

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Using a three dimensional formalism previously established, the freedom to choose the coupling functiong(&thgr;, &phgr;) between the polar angles defining the mean trajectory in the field‐free region of the analyzer is exploited to improve the properties of the instrument. It is shown that a partial correction to thezvariation of the image when &thgr; and &phgr; vary can be achieved yielding a maximum excursion &Dgr;z /zof 6% for a total &thgr; excursion of &Dgr;&thgr; = 18° at &phgr; = const with a corresponding increase of resolving power by a factor of 2. Indications are also given on the possibility of cylindrization of the focal surface.

ISSN:0034-6748    

DOI:10.1063/1.1686389

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The effects of fringing fields at the entrance and exit windows of the parallel plate electrostatic particle analyzer on the trajectory of particles is studied taking into account the finite thickness of the condenser plate bearing the windows. The influence of the physical dimensions of the spectrograph on the field variation is assessed together with that of a grounded plate parallel to the condenser and located in the entrance‐exit region. A set of inequalities expressed in terms of the physical dimensions of the instrument is deduced to define a reference model spectrograph of known characteristics and minimal electric field distortion with the help of which any actual instrument may be studied using the electrostatic scaling laws.

ISSN:0034-6748    

DOI:10.1063/1.1686390

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Using the high velocity helium jet and the cold finger simultaneously, the anticontamination of the sample in vacuum chamber of the probe can be achieved for at least the first 12 min. A limit of detection (LOD) of carbon of 0.03 wt % in steel samples has been achieved. Further, it has been shown that the anticontamination technique extends the general usefulness of the electron probe for obtaining the carbon concentration profile of carburized steel.

ISSN:0034-6748    

DOI:10.1063/1.1686391

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A technique is described for carrying out temperature‐jump experiments at pressures up to 1000 atm, thus allowing the measurement of activation volumes for reactions in the &mgr;sec‐sec range. The main features of the new technique are an electrical lead which has been tested to 2000 atm and 10 000 V ungrounded electrodes, and a flexible cell to transmit pressure from the external fluid to the solution.

ISSN:0034-6748    

DOI:10.1063/1.1686392

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A possible source of error in measuring luminescent decay times as a result of photomultiplier saturation is discussed. Photomultiplier saturation can occur by exceeding the maximum linear output current, which decreases with increased light pulse duration. For this reason it is necessary to calibrate the instrument response appropriate to the lifetime and light intensity being measured.

ISSN:0034-6748    

DOI:10.1063/1.1686393

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A new type of permanent magnet bearing with short axial gaps and intrinsic radial stability for ferromagnetic suspension of small and heavy rotors at almost negligible power is presented.

ISSN:0034-6748    

DOI:10.1063/1.1686394

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A simple vacuum casting device for use with a conventional arc furnace is described. It has been possible to cast refractory metals and intermetallic compounds into rods of 1.6 mm diam and up to 50 mm long without modifying the arc furnace.

ISSN:0034-6748    

DOI:10.1063/1.1686395

出版商:AIP    

年代:1973

数据来源: AIP