摘要:

A 16‐MHz piezoelectric quartz resonator has been used to build up a high‐resolution deposition rate monitor. A direct counting allows a resolution of 1 ng/cm2at a rate of one reading per second. Direct computer interface and increase in the voltage excitation above the plasma noise level have been successfully used to monitor the deposition rate in a dc sputtering apparatus.

ISSN:0034-6748    

DOI:10.1063/1.1144445

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

One of the most important properties of brittle materials is static fatigue. To measure this property, the specimen is loaded under constant stress and the fracture occurs after an elapsed period of time. The scatter in this time is large, and to obtain a good statistical representation it is necessary to test a large number of samples (over 20). Due to this scatter, the time for some of the tests could be large, and a period of several months might be necessary to test all the samples. In this article we describe an automatic optical detector for fracture that was employed to study the static fatigue of transparent materials. The main advantages of this instrument are (i) automatic registration of fracture for long periods of time, (ii) application on bending tests (this reduces the testing space) of low strength materials, and (iii) the cost is low and the number of samples can be increased with practically no increase in cost.

ISSN:0034-6748    

DOI:10.1063/1.1144446

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A simple calibration chart is presented for correlating the Preston tube reading directly with the friction velocity. This chart provides a quick and easy way to obtain the friction velocity (an important scaling velocity in turbulent flow studies) and consequently the wall shear stress. In addition the chart overcomes most of the drawbacks of previous Preston tube calibration methods. A comparison between friction velocities obtained using the chart and the corresponding values obtained from Patel’s calibration shows a good agreement with a maximum difference of 5%.

ISSN:0034-6748    

DOI:10.1063/1.1144390

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A self‐rectifying electron beam melting technique is described. Utilizing an ac power supply, in contrast to the more usual dc supply, theinsituself‐rectifying approach offers a simple and very inexpensive means of producing metallic pendant drops for use in containerless melt‐processing experiments.

ISSN:0034-6748    

DOI:10.1063/1.1144391

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

Synchronized trains of 5 ps pulses at two wavelengths were generated in a single‐cavity synchronously pumped dye laser containing a mixture of two dyes in a single jet and intracavity spatial masking for frequency selection. The utilization of this dual wavelength dye laser to monitor the relaxation of photoexcited carriers in multiple quantum wells was demonstrated.

ISSN:0034-6748    

DOI:10.1063/1.1144392

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

Large, off‐axis epoxy paraboloids with high surface accuracy (26 &mgr;m rms) were generated by spinning a bowl containing a long cure time, low viscosity epoxy. This note also describes procedures for generating and measuring meter‐class surfaces.

ISSN:0034-6748    

DOI:10.1063/1.1144393

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A convenient treatment that can be applied to tungsten scanning tunneling microscope tips prepared by electrochemical etching in aqueous base is described. The treatment removes the majority of the tungsten oxide layer present after etching and produces a very stable tunnel junction and a high success rate in preparing tips for atomic‐resolution imaging.

ISSN:0034-6748    

DOI:10.1063/1.1144394

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A simple and low‐cost pulsed atomizer for resonance ionization spectroscopy of Mo has been produced. The atomizer has made it possible to measure the isotope shift of Mo with a 200 &mgr;g sample in resonance ionization spectroscopy.

ISSN:0034-6748    

DOI:10.1063/1.1144395

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

Use of an intense and narrow linear‐shaped x‐ray source is essential to improve the quality of the extended x‐ray absorption fine‐structure measurements in a laboratory. To this end, an x‐ray generator with a large rotating anode, designed for dedicated use of point‐shaped focal spot, was modified to provide a linear‐shaped focal spot of ∼0.1 mm in width at an exit angle of 6°. The maximum allowable current was 600 mA, which has never been realized so far using a conventional x‐ray linear focal spot.

ISSN:0034-6748    

DOI:10.1063/1.1144396

出版商:AIP    

年代:1993

数据来源: AIP