摘要:

Experiments have been undertaken to determine the length and width dependence of electromigration‐induced failure time in aluminum thin‐film conductors. A statistical model is presented and compared to the experimental data. The significance of the experimental data and the statistical model are discussed in terms of randomly distributed structural defects which produce flux divergences during electromigration.

ISSN:0021-8979    

DOI:10.1063/1.1658395

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

It is shown that the activation volume for diffusion or steady‐state creep at high temperature (>0.5Tm) can be estimated for all crystalline solids if the crystal structure, valence, entropy of melting, and volume change on melting are known. The calculated results agree well with the available experimental data for metals and compounds. Calculations performed for a number of crystalline materials show that the activation volume is a function of the crystal structure and that negative activation volumes are obtained for those materials that contract on melting. These results suggest that diffusion in the solid state occurs by a mechanism similar to the ``relaxion'' mechanism as originally proposed by Nachtrieb and Handler. In our proposed model the thermally activated process in diffusion involves the cooperative formation of a liquid‐like cluster of atoms surrounding a vacant lattice site. Such a model predicts negative activation volumes and satisfactorily explains the influence of different crystal structures on the magnitude of the activation volume obtained.

ISSN:0021-8979    

DOI:10.1063/1.1658396

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

During air cooling from a high‐temperature anneal, vacancy currents were observed to cause zinc to segregate around vacancy precipitate cavities in aluminum. From the vacancy and zinc impurity currents directly measured in this experiment, a maximum value of the ratio of vacancy jump frequencies away from and around a zinc impurity atom in aluminum is determined. This limiting ratio suggests a small attractive interaction between a vacancy and a zinc impurity and/or an increase in the jump frequency of aluminum atoms around the undersized zinc atom. The segregation that would be produced around grain‐boundary vacancy sinks during quenching and irradiation was computed from the experimental values of the ratio of the vacancy current and the vacancy‐generated impurity current measured in this and other experiments. It was found that moderate and very large changes in grain‐boundary solute concentration could be expected during quenching and irradiation, respectively.

ISSN:0021-8979    

DOI:10.1063/1.1658397

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The general theory for the vector potential produced by a sinusoidal current of finite cross section is developed and applied to a coil encircling two concentric, spherical shells of finite electrical conductivities and permeabilities. Linear, isotropic, and homogeneous media are assumed throughout the analysis. First, the Green's function solution is obtained, and then the principle of superposition is used to effect the desired result. A number of physically observable phenomena—such as the impedance, the power loss due to the presence of the conductors, and the time‐averaged electromagnetic force on the conductors—are subsequently calculated from the vector potential. The treatment is sufficiently general to allow the solution of a number of difficult problems of electromagnetic induction, while each of the expressions obtained for the physically observable phenomena is in terms of an infinite sum that may be readily evaluated on a computer.

ISSN:0021-8979    

DOI:10.1063/1.1658398

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The general theory for the vector potential produced by a sinusoidal current of finite cross section has been developed in a preceding paper.1In the present work, this theory is applied to a coil between a number of plates of finite electrical conductivities and permeabilities. Linear, isotropic, and homogeneous media are assumed throughout. The Green's function solution is first obtained, and the principle of superposition is then used to effect the desired result. A number of physically observable phenomena, such as the impedance, the power loss due to the presence of the conductors, and the time‐averaged electromagnetic force on the conductors are subsequently calculated from the vector potential. The treatment is sufficiently general to allow the solution of a number of difficult electromagnetic induction problems, while each of the expressions obtained for the physically observable phenomena is in terms of an infinite integral that may readily be evaluated on a computer. In all cases for which experimental measurements have been made, the agreement between calculated and observed values is within the limits of experimental error. Preliminary investigations of other cases tend to support the validity of the corresponding theoretical expressions.

ISSN:0021-8979    

DOI:10.1063/1.1658399

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Trichel streamers and their transition into a negative pulseless glow were investigated by simultaneous recordings of the discharge current and light emission. Both the streamer and the glow modes of discharges have been found to develop in parallel at low cathode potentials. The transition to a pulseless glow mode depends upon the quenching effect of the ion space charge in particular field conditions. Critical values of the repetition rate of Trichel streamers were found to depend on the electrode slenderness and also on the resistance of the cathode to ion bombardment. Practically, a repetition rate exceeding 10 MHz is difficult to obtain under normal atmospheric conditions because of the rapid cathode deterioration.

ISSN:0021-8979    

DOI:10.1063/1.1658400

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The classical boundary layer theory is extended for an elasticoviscous fluid flow over porous boundary. A method is developed from which the results for the stagnation flow, the flow along a flat plate, etc. can be derived as special cases. The flow near a stagnation point is considered in detail. It is found that the main effect of suction is to increase the velocity in the elasticoviscous boundary layer and to decrease the stress on the boundary.

ISSN:0021-8979    

DOI:10.1063/1.1658401

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The theory of the transfer of charge from an electrified surface layer through the bulk of a dielectric is developed for transient space‐charge‐limited current conditions. The modifications required when conduction is included and when diffusion is included are indicated. Comparison with published data for polyethylene indicates carrier mobilities of the order of 10−11cm2V−1sec−1at room temperature.

ISSN:0021-8979    

DOI:10.1063/1.1658402

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Hydrostatic pressures of up to 16 kbar are shown to increase the net acoustoelectric gain in semiconducting CdS and CdSe. Decreasing conductivity with pressure in CdS is attributed to a decrease in both mobility and carrier concentration whereas no significant changes were observed in CdSe. The frequency of maximum gain, as calculated from linear theory, decreases with pressure in CdS.

ISSN:0021-8979    

DOI:10.1063/1.1658403

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The paper presents the pressure derivatives of single‐crystal NaCl in the temperature range of 180°–300°K. The data have been used to calculate the mode Gru¨neisen parameters. We have also predicted the shock‐velocity and the particle‐velocity relationship using the ultrasonic data at 300°K.

ISSN:0021-8979    

DOI:10.1063/1.1658404

出版商:AIP    

年代:1970

数据来源: AIP