摘要:

A new model for determining the time‐dependent behavior of exploding metallic fuses is formulated. The model draws on an atomic data base and gives insight into the temporal behavior of the material density and temperature of the fuse as well as the nonlinear electrical circuit interaction. The model includes an embedding insulating tamper and leads to a plausible explanation of fuse ‘‘restrike.’’ The model predicts time‐scale compression of 500 for inductive store systems powered by explosive driven magnetic flux compression generators. A scenario for achieving multimegajoule foil implosions is predicted.

ISSN:0021-8979    

DOI:10.1063/1.334569

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We calculated the turnover temperaturesTtoof crystallographically doubly rotated quartz plates vibrating in the thickness mode. In addition to the known cuts situated along the loci of zero value of the first‐order temperature coefficient of frequency, there is another family of orientations, withTto≥75 °C, which, compared to other singly or doubly rotated cuts, are relatively insensitive to crystallographic orientations. We designate these orientations as theAKcut. We report experimental static frequency as a function of temperature characteristicsf(T) for 14AK‐cut orientations, with angular combinations 30°≤&fgr;≤46.1° and 21° ≤&thgr;≤28.44°.Ttovalues are between 80 and 150 °C, in good agreement with computations. Thef(T) curves have been fitted with third‐order polynomials. Compared to the fundamental mode of vibrations, the 3rd overtone shows a larger number of modes, and resonance amplitudes are weaker. The frequencies of the harmonic and anharmonic modes are in fairly good agreement with calculations based on a trapped energy resonator model, including effects of coupled thickness shear and thickness twist.

ISSN:0021-8979    

DOI:10.1063/1.334570

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Lasers are well suited to penetration welding as they can supply large amounts of power to a very small volume far from the surface of the workpiece. This paper reports the results of calculations performed with the aid of a mathematical model for the flow of heat and the motion of the molten metal surrounding the keyhole formed by the laser. The equations were solved with the aid of an approximate analytical solution for low welding speeds, and a computer program for higher speeds. A number of different materials are considered and graphs of the temperature distribution and the stream function describing the fluid motion are shown for a typical case. Relationships between the weld width, the power absorbed per unit thickness of the workpiece, and the speed of welding are investigated in detail. Over the range of welding speeds considered, the relationships given by the approximate analytical solution were found to be close to those obtained by numerical integration of the exact equations, even though the fine details of the solution, such as the ratio of the weld width to the total length of the weld pool at a given instant, or the details of the fluid motion, are substantially different.

ISSN:0021-8979    

DOI:10.1063/1.334571

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Dispersion properties of the electromagnetic (em) waves propagating through a planar helix are investigated. A dispersion relation is obtained which includes influence of the outer metal shield on the em wave propagation. It is shown that the phase velocity of em waves reduces as the metal shield is brought closer to the planar helix.

ISSN:0021-8979    

DOI:10.1063/1.334572

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Hollow‐anode discharge represents a new type of discharge which is realized in a diode consisting of a cylindrical cathode and special type of hollow anode whose inner surface only is conductive. The cylindrical cathode focuses electrons toward the hollow anode placed in the center of curvature, increasing the density of high‐energy electrons and efficiency of excitation and ionization in the hollow aperture of the anode. Optical spectrum consists of intense ion lines of the operating gas without anode or cathode material lines.

ISSN:0021-8979    

DOI:10.1063/1.334573

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A new photoacoustic cell has been constructed to measure laser beam power. The sample, a thin brass disk, is on the front of the cell in place of the conventional window. For the thickest sample used (127 &mgr;m), the cell response was found to be linear with laser beam power up to 1.8 W, the maximum power delivered by the laser.

ISSN:0021-8979    

DOI:10.1063/1.334574

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The output power and saturation parameter of an air‐breathing electric discharge CO2laser are reported. An output power of 79 W was obtained with an energy‐conversion efficiency of 5.1% and a specific power of 12.5 J/g. The saturation parameter of ∼30 W/cm2was determined by measuring the gain with and without lasing. We also discuss the influence of He‐ and Ar‐gas addition on the output power of the present laser.

ISSN:0021-8979    

DOI:10.1063/1.334575

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The mean speed of Ni and Pd molecular beams effused from a nonequilibrium source has been measured by means of a phase‐sensitive detection technique and is compared with the statistical mean speed. The mean speeds are determined to be 65,000 and 52,000 cm/s for Ni (1450 °C) and Pd (1320 °C), respectively. The ratio of the mean speed with respect to the statistical mean speed varies from 0.9 to 1.1, and from 0.92 to 1.18 for Ni and Pd, respectively, for the modulation frequency range 300–1200 Hz.

ISSN:0021-8979    

DOI:10.1063/1.334576

出版商:AIP    

年代:1985

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.335509

出版商:AIP    

年代:1985

数据来源: AIP