摘要:

Collection efficiency for carriers generated by visible light and potential path distributions have been studied inp‐i‐nstructures formed fromp‐type silicon after compensation by the lithium drift method. The experimental results show that the characteristics of the resultant devices are similar to those expected when an excess donor concentration excists in the compensated region. The effects of high‐field, reverse‐bias, room‐temperature storage indicate that a reduction in the donor concentration takes place under these conditions, resulting in a device behaving more like ap‐i‐nstructure.

ISSN:0021-8979    

DOI:10.1063/1.1709039

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The influence of charging current rise rate on the maximum operating current was determined for a 42‐layer Nb&sngbnd;Zr solenoid 15.24 cm long with an i.d. of 3.05 cm and an o.d. of 5.74 cm which generated a magnetic field of 1.4 kG/A. A rise rate of 10.7 A/sec (15 kG/sec) was found to lower the maximum operating current of this solenoid by ∼30%. In addition, the rise‐rate dependence of the transition current was determined with various configurations of built‐in electrical shorts. In all cases, the presence of a short greatly increased the rise rate dependence, and in several cases led to depression of the transition current by more than 50% for rise rates as small as 0.2 A/sec (0.28 kG/sec). These results indicate that the strong rise‐rate dependence of the transition current observed in some superconducting solenoids arises from the presence of shorts, and is influenced more strongly by the rate of change of field than by the current rise rate. Several relations have been derived which accurately predict the rise‐rate dependence of the critical current of a shorted superconducting solenoid.

ISSN:0021-8979    

DOI:10.1063/1.1709040

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A fortranprogram has been developed for the IBM 1620 computer in order to calculate Buckingham orB‐numbers, dimensionless products of variables, from the laws of physics. For a given set of physical quantities, the corresponding set ofB‐numbers is invariant under changes of the reference set of dimensions, such as length, mass, time, charge, and temperature. Complete and nonredundant sets ofB‐numbers are obtained for 35 formulas from a representative branch of physics (solid‐state). A systematic procedure is established for coding and cataloguing these formulas in terms ofB‐numbers. It is anticipated that decoding techniques can be applied to this catalogue to yield information on the interrelationships among and redundancy in the laws governing physical phenomena.

ISSN:0021-8979    

DOI:10.1063/1.1709041

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The effect of electron binding on the incoherent scattering of gamma rays in uranium in the energy region 320–1332 keV is studied using the total cross sections of Colgate [Phys. Rev.87, 593 (1952)] and Wyard [Phys. Rev.87, 165 (1952)]; total photoelectric cross sections of Rakavy and Ron [Phys. Letters19, 207 (1965)]; and coherent‐scattering cross sections based on Thomas—Fermi calculations [W. Brown, Boeing Co. Report D2–125137–1 (Dec. 1966)]. Combining these data, it is concluded that the effect of electron binding on the incoherent‐scattering cross section for uranium in the region 320–662 keV exceeds that predicted by the Thomas—Fermi model.

ISSN:0021-8979    

DOI:10.1063/1.1709042

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The concentration of argon in sputtered nickel films has been obtained as a function of the film‐growth temperature, the discharge pressure, and of the energy (bias voltage) with which the argon ions bombard the growing film. The concentrations vary from about 10−1argon atoms/Ni atom to 10−4argon atoms/Ni atom, depending upon the conditions during film growth. The incorporation of both argon and nitrogen into nickel films is interpreted on the basis of results previously obtained from sorption studies in a more‐idealized system on a pre‐existing nickel surface.

ISSN:0021-8979    

DOI:10.1063/1.1709043

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An explicit expression for the velocity potential governing the flow produced by impact of a liquid drop against a liquid is given. With use of this velocity potential, an equation is derived from which the cavity depth and the velocity of the cavity wall, for various times after the instant of impact, can be obtained. With use of this velocity potential an expression for the initial pressure in the fluid is also obtained. Good agreement is found between calculated and observed values of cavity depth at various times after the instant of impact and between the calculated initial pressure and the water‐hammer pressure.

ISSN:0021-8979    

DOI:10.1063/1.1709044

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Measurements were made of the phase, attenuation, and coupling constants of circularly polarizedm=±1 traveling helicons inn‐type InSb cylinders at 54.2 MHz. Values ofkHabetween 0.25 and 3.0 were achieved by varying the temperature from 81° to 373°K and the magnetic field from 0 to 11 kG. The quantitykHis the infinite‐medium phase constant andais the cylinder radius. Theoretical calculations were made extending earlier work to the values ofkHaand &ohgr;c&tgr; covered experimentally, where &ohgr;cis the cyclotron frequency and &tgr; is the collision time. The results differ from the earlier work, and in particular, it is found that them=×1 modes do not have the same polarization near the cylinder axis. Transverse magnetoresistance and Hall measurements were made to determinekHaand &ohgr;c&tgr;. The agreement between experiment and guided theory was found to be relatively good. Both of the guided helicon modes excited had higher phase velocities and much larger attenuation constants than the values calculated from infinite‐medium theory. These results indicate difficulty in achieving the conditions necessary for predicted two‐stream helicon instabilities.

ISSN:0021-8979    

DOI:10.1063/1.1709045

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The objective of this work has been to correlate x‐ray and infrared experimental scattering phenomena. X‐ray topography and polarized infrared radiation have been used to study the stresses induced in single‐crystal silicon wafers by electron‐beam heating. The results of this work are discussed in relation to previous results of various investigators for stresses produced by several mechanisms. X‐ray topographs showing four‐lobed rosette patterns are presented together with an infrared birefringence pattern of the same electron‐beam‐spot area. Also illustrated and discussed is a triangular macrodefect observed by x‐ray topography. The results presented herein have led to the conclusion that x‐ray rosette patterns and infrared birefringence occur together and are due to thermally induced residual stress surrounding the electron‐beam‐spot areas. The results also indicate the need for additional experimental and theoretical work on the relation between scattering phenomena observed for electromagnetic radiations of different wavelengths.

ISSN:0021-8979    

DOI:10.1063/1.1709046

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

It is shown that failure to take into account the nonuniformity of stress in particles near a surface may lead to gross errors when stress measurements are made by x‐ray diffraction on crystallites of one phase dispersed in a matrix of another phase. In particular, the measured strains may depend on the wavelength of the radiation used, and on the particle size of the dispersed phase even though the actual strains in particles not too close to the surface are not dependent on particle size. The measured strains may differ by a factor of two or three from the strains in particles below the x‐ray penetration depth. Experimental evidence on a vitreous china (quartz—glass) system is presented, showing that the observed variation of strain with wavelength and particle size is of about the magnitude predicted by calculation on a simple model system.

ISSN:0021-8979    

DOI:10.1063/1.1709047

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The effect of gas heating and volume recombination on the constriction in the positive column in glow discharges is analyzed theoretically. Specific results are obtained for helium by solving conservation and diffusion equations for the case where energy balance is dominated by elastic collisions. The degree of constriction is found to be an increasing function of the two parametersRpandIp, whereR, I, andpare the tube radius, tube current, and gas pressure, respectively. In helium the constriction is predicted to set in at a value ofRpof about 750 cm·Torr. This value is much larger than the value (≈30 cm·Torr) at which elastic collisions gain control of the energy balance in helium. Some results calculated for neon gas indicate that volume recombination in the heavier inert gases becomes effective before elastic collisions gain control of the energy balance.

ISSN:0021-8979    

DOI:10.1063/1.1709048

出版商:AIP    

年代:1967

数据来源: AIP