摘要:

A simple design is described for a sensitive thin film thermopile (12 V W−1) which is suitable for measurements on low energy neutral beams in the range 300 eV‐3keV. The device has been used as a secondary standard to calibrate fast response (&tgr; ∼ 10−6sec) neutral particle energy analyzers which incorporate gas stripping cells.

ISSN:0034-6748    

DOI:10.1063/1.1686633

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A versatile TV‐camera system is proposed for the analysis of fluctuating illumination patterns. The system consists of a pulsed slow‐scan TV camera followed by a wideband analog recorder and an electronic computer. The system is described in detail. The results of preliminary tests carried out on a prototype built in our Institute are reported and discussed.

ISSN:0034-6748    

DOI:10.1063/1.1686634

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A new, highly accurate technique for the measurement of linear dichroic spectra is described. This technique, named PNP method, is based on the measurement of absorption spectra with two successive scans, one with polarized light and the other with nonpolarized light. The main advantages of this method are as follows: (1) The use of a simple device including two identical units consisting each of a polarizer and two depolarizers; (2) recording of continuous spectra without rotating either the polarizer or the measured sample; (3) the possibility of accurate recording of polarization spectra of highly dichroic samples and of samples showing very sharp bands; (4) the possibility of using wider slits and the whole range of the spectrophotometer, without requiring additional resolving power.

ISSN:0034-6748    

DOI:10.1063/1.1686635

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A method is described whereby high‐resolution measurements of the derivative of the electron current transmitted through a gas may be made without the use of deflection or magnetic fields. The method consists of modulating a retarding element and the interaction region with signals which are 90° out of phase. It is shown that when the transmitted current is measured by a phase‐sensitive detector which is referenced to twice the modulation frequency, the output signal is proportional to the derivative of the transmitted current and is characteristic of a monoenergetic beam. Results of performance tests on helium are presented and discussed. The tests show that the resolution is essentially equal to the average of the two modulation amplitudes. In the case of the 22Sresonance in He−, a resolution of 29 meV with a signal‐to‐noise ratio of better than 400 has been obtained. Resolutions as good as 10 meV have been obtained with poorer signal‐to‐noise ratios.

ISSN:0034-6748    

DOI:10.1063/1.1686636

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A simple method of measuring low currents from current sources (transducers) is described. This method has a noise equivalent to an input current of 5 fA (5 × 10−15A). A possible modification for 1 fA noise input is given. In this method of measurement, a charge generated by a current source is collected on a capacitor during a fixed time interval. In discharging the capacitor, an ac pulse is produced which is then amplified, and the required information extracted.

ISSN:0034-6748    

DOI:10.1063/1.1686637

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Construction of a pulsed xenon ion laser, which has a combined peak power on all visible lines of over 80 kW is described. Design of the laser and the pulsing circuit is detailed, and the light pulse shape, peak power and electrical effieciency of the laser are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1686638

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A fast, rugged, electronic circuit is described which predicts an impending switching surge flashover in a long air gap and diverts the discharge energy into a triggere'd bypass gap. Prediction is based on the amount of charge injected into the gap by the high voltage electrode. A protective gap could be designed which would operate only if the insulation being protected were about to fail. This could significantly improve the techniques of insulation coordination and has important implications for studies of the mechanisms of the long spark.

ISSN:0034-6748    

DOI:10.1063/1.1686639

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An automated constant pressure reactor for measuring the solubilities of slightly soluble gases in aqueous solution is described. The apparatus can also be used for kinetic studies of aqueous reactions involving a gaseous reactant or product. The system can be operated unattended and therefore can be used for prolonged experimentation. Results obtained using the apparatus for solubilities of methane and butane in triple distilled water at atmospheric pressure and 25°C are compared with those reported in the literature.

ISSN:0034-6748    

DOI:10.1063/1.1686640

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An inexpensive device useful for accurate positioning of electrodes, parts, tools, and other implements has been developed using audio speakers, linearly actuated potentiometers, and conventional power supplies. It is designed to have three independent orthogonal directions of motion; however, devices to control movement in one or two directions are also easily constructed.

ISSN:0034-6748    

DOI:10.1063/1.1686641

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A device is described which facilitates the convenient photographic recording of two separate images on 16 mm cine film. Two examples are given of the use of the device in conjunction with hot wire and hot film anemometers, in experimental studies of an unsteady fluid flow system.

ISSN:0034-6748    

DOI:10.1063/1.1686642

出版商:AIP    

年代:1974

数据来源: AIP