摘要:

In order to achieve turbulence measurements in supersonic flows the frequency response of CTA is tested and improved. A fast and convenient technique to determine electrically the frequency response is proposed; the response is also tested by direct heating of the wire by means of a laser beam. The two techniques are in good agreement. Under certain experimental conditions (M=2,Re&fgr;=400) it is possible to use CTA with a satisfactory frequency response up to 250 kHz and overheat ratios down to 0.07. In these severe operating conditions, the square‐wave test technique seems to be not sufficient to ensure optimum settings and it is necessary to use symmetrical bridges with fine adjustment of offset voltage.

ISSN:0034-6748    

DOI:10.1063/1.1136180

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A complete working design for highly stable grating controlled N2O and CO2lasers is presented. The lasers are suitable for general high resolution spectroscopy, frequency mixing and clock applications.

ISSN:0034-6748    

DOI:10.1063/1.1136181

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A circuit is described which permits a hysteretic ratio to be graphed versus another experimental parameter. The hysteretic ratio can be defined either: (a) by the two discontinuities of theI–Vresponse (or more exactly the two discontinuities in (dV/dt) or (b) by the two polarity changes (as in ferromagneticBvsHcurves). The circuit features a large dynamic range (≳40 dB with no adjustments) and works well for modulation frequencies between 10−3and 300 Hz.

ISSN:0034-6748    

DOI:10.1063/1.1136182

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Circuitry is presented for the measurement of surface potential changes upon adsorption of gases on a metal foil or film by the static capacitor method. The circuit operates in the usual manner applying a backing off potential which opposes the flow of current from the cell comprised of the foil or film and a reference surface. The advantages of the present circuit include simplicity, low cost, fast response time, no moving parts, and the requirement of only one low voltage, dual‐polarity power supply.

ISSN:0034-6748    

DOI:10.1063/1.1136165

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple method of reducing the total measurement time in signal averaging is described. The method uses averaging over autocorrelation estimates rather than over the signal directly. The method may be useful in certain cases where the repetition rate is small.

ISSN:0034-6748    

DOI:10.1063/1.1136166

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A lock‐in amplifier can be considered to be a special case of the more general box‐car averager. Expressions for the output noise voltage of lock‐in amplifiers are deduced from the corresponding results derived earlier for box‐car averagers. Deviations from the simple (4RC)1/2law are shown to exist in the case of nonwhite noise.

ISSN:0034-6748    

DOI:10.1063/1.1136167

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A pressure jump relaxation technique is described to study fast reactions in solution under pressure up to 1.5 kbar. The mechanical relaxation time of the instrument is 0.5 ms.

ISSN:0034-6748    

DOI:10.1063/1.1136168

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We describe a simple design modification which will solve the spurious surface charging effects associated with the use of sweep plates to investigate gaseous ions. The procedure involves using a fluid insulator to electrically isolate the electrometer electrode.

ISSN:0034-6748    

DOI:10.1063/1.1136183

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The design of a rear viewing, retractable low energy electron diffraction assembly is described.

ISSN:0034-6748    

DOI:10.1063/1.1136184

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Small holes, approximately 0.25 mm diameter, are drilled through IR windows (NaCl, KCl, CsBr) 3.2 mm thick. Thermocouples wires (0.13 mm diam) are inserted and sealed with ’’Vacseal,’’ a silicone resin. After curing, a reasonably durable‐vacuum proof seal exits. The method provides a very simple, inexpensive procedure for installing thermocouples in IR spectroscopy and reaction cells.

ISSN:0034-6748    

DOI:10.1063/1.1136185

出版商:AIP    

年代:1980

数据来源: AIP