摘要:

A special Bridgman opposed diamond anvil apparatus was constructed to generate useful static pressure to 50 kbar at ambient temperatures. It was designed to function in the environment of a nuclear reactor and to occupy 65 cc. A method of bombarding materials under pressure with fission fragments is described.

ISSN:0034-6748    

DOI:10.1063/1.1720350

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Whiskers of iron, copper, tin, and silicon were obtained and used as microelectrodes in a spark erosion process. Silicon slices, thin metal sheets, whiskers, and thin films were successfully machined. Holes with diameters as small as 1 &mgr; were produced through thin films of tantalum.

ISSN:0034-6748    

DOI:10.1063/1.1720351

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A system is described for using uhf dipole resonance in uniaxially anisotropic permalloy films to detect and measure weak magnetic fields. The dipoles are pulled to a position at right angles to the easy axis where they approach a condition of infinite permeability. Dispersion of the anisotropy over the film causes a severe degradation of the permeability but is largely overcome by low level modulation of the field with a low frequency signal. The net movement of the dipoles in response to the weak field being tested is measured both in magnitude and direction using simple uhf dipole resonance, the detected output being phase detected in turn with the low frequency source acting as the reference. Experimental results, which closely approach the theoretically predicted results, have been obtained down to 10−9Wb/m2sensitivity in 1 cps bandwidth in ordinary laboratory environments and using a 35 dB noise figure receiver. Means for greatly improving both the sensitivity and bandwidth are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1720352

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A method of growing cobalt crystals by the Bridgeman technique is given. Crystals are grown in vacuum utilizing induction heating as the power source. Cobalt crystals in the hexagonal phase have been obtained 0.95 cm diameter by 6.26 cm long.

ISSN:0034-6748    

DOI:10.1063/1.1720353

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A transformer is described which delivers 2 MA into a low impedance load through a coaxial output line of about 6.35 mm inner conductor diameter and 12.7 mm cavity diameter. The transformer primary is connected to a 20 &mgr;F, 50 kV capacitor bank by forty‐eight flexible coaxial cables. The ringing frequency of the system with the secondary shorted is 70 kc.

ISSN:0034-6748    

DOI:10.1063/1.1720354

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A technique of averaging two resistivity measurements, each made using a different pair of current probes of a square array on an infinite sheet, has been developed. It is shown in theory and practice that when one probe is common to each of the two measurements, an average eliminates all first order errors due to misalignment of the array. An electronic averaging circuit which provides a continuous single meter measurement of sheet resistivity is presented. Data taken with 1.27 mm infinite sheet probe assembly are shown to have a repeatability of ±0.33% (3&sgr;) on a 145 &OHgr; per square sample. This particular system has a useful range of 0.1 to 10 000 &OHgr; per square. The circuity developed for the infinite sheet method is also shown to be applicable to the bounded sheet method (Van der Pauw technique). A novel infinite sheet probe assembly design is illustrated.

ISSN:0034-6748    

DOI:10.1063/1.1720355

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A previous study of the signal and noise characteristics of the Pound‐Knight‐Watkins (PKW) marginal oscillator circuit has been extended to the Robinson NMR circuit. It is shown that although the signal and noise characteristics of the Robinson circuit are markedly different from the PKW oscillator, the signal‐to‐noise ratios are similar.

ISSN:0034-6748    

DOI:10.1063/1.1720356

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A method of quenching a specimen subjected to a tensile stress at elevated temperatures has been developed. Tensile tests with stress, time, and temperature as variables are possible. The cooling rate of specimens in the 600°C range can be controlled from ¼ to 25°C/sec.

ISSN:0034-6748    

DOI:10.1063/1.1720357

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A simple, relatively accurate method for determining the Hg vapor pressure of amalgams at elevated temperatures is described. The transmission of 2537 Å radiation through an evacuated quartz optical cell containing the amalgam is compared with that of a similar cell containing only Hg, using a spectroradiometer. After plotting log transmission vs 1/T°K for each of the cells, the Hg vapor pressure of the amalgam is found by determining the temperature at which the Hg cell shows the same transmission as the amalgam, and reference to a table of Hg vapor pressure vs temperature.

ISSN:0034-6748    

DOI:10.1063/1.1720358

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A derivation is given for the resistance of the sheath surrounding a floating probe and the corresponding limitation to the frequency response. The bandwidth is increased by using probes with built‐in attenuators which measure fluctuations in floating potential, electric field, and ion saturation current at frequencies up to 40 MHz with plasma densities as low as 109cm−3.

ISSN:0034-6748    

DOI:10.1063/1.1720359

出版商:AIP    

年代:1966

数据来源: AIP