摘要:

An apparatus that is capable of measuring thermal diffusivity between 80–500 K using a modified A˚ngstro¨m method is described. The main feature of the apparatus is its simplicity. A detailed description of the equipment and the experimental procedure as well as the difficulties that can be encountered are given. The results of measurements on samples covering a wide range of thermal diffusivities are also given.

ISSN:0034-6748    

DOI:10.1063/1.1136158

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

This linear amplifier employs moderate‐voltage power supplies and components to generate high‐voltage pulses of arbitrary shape on a &mgr;s time scale. A linear version of the Marx generator, it is limited to a small duty fraction, but can deliver a large multiple of its supply voltage. Its initial application was generation of specially shaped field–ionization pulses in studies of Rydberg atoms.

ISSN:0034-6748    

DOI:10.1063/1.1136159

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

This paper describes the design and implementation of a versatile and compact signal averager interface between a Biomation 6500 transient recorder and an LSI‐11 microcomputer. The design allows for fast signal averaging in excess of 1 kHz and is also easily software configurable and controllable. This permits the rapid recovery of high‐speed waveforms at a minimum sampling time of 2 ns (500 MHz sampling rate). The interface has been incorporated into an LSI‐11 system using the RT‐11 V3B operating system and found to perform very satisfactorily.

ISSN:0034-6748    

DOI:10.1063/1.1136160

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The instrument described here was designed as a laboratory aid for the visually handicapped. It is basically a 3 1/2‐digit multimeter with speech output; however, it has added functions which extend its usefulness beyond the ability to measure the usual ranges of ac and dc voltage and current. The device can function as a thermometer, a pH meter, a 6‐digit timer, and an events counter. Two voltage‐to‐frequency (V/F) converters make it useful as an audible comparator and peak detector. An integrator is realized by using the counter to count the pulse train from a V/F converter which monitors the input signal. A low‐level differential channel is provided for interfacing to instruments with recorder outputs, such as gas chromatographs. Spoken values of measured quantities are accompanied by sign, decimal point, and units. The instrument can also interface with other digital devices through 42 lines of parallel digital input–output. It can convert seven parallel BCD digits into speech or it can output BCD data from its counter or converter to a microcomputer.

ISSN:0034-6748    

DOI:10.1063/1.1136161

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

When commercial reflection cavities are utilized for electron paramagnetic resonance (EPR) experiments at high‐microwave field intensities or for saturation transfer–electron paramagnetic resonance (ST–EPR) measurements, dispersion signals exhibit substantially worse signal‐to‐noise than absorption signals due to the increased sensitivity of the former to source frequency modulation noise. The development and testing of a TM110×TM110bimodal cavity which completely eliminates the source noise problem is described. This cavity is used to obtain EPR and ST–EPR spectra of a variety of commonly encountered spin‐labeled biological samples. When samples are contained in capillary tubes, this TM110×TM110cavity often permits the realization of better signal‐to‐noise than can be obtained with commercial reflection cavities.

ISSN:0034-6748    

DOI:10.1063/1.1136162

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A thermal interlock system with a quick response time has been developed to protect high‐power magnetic coil systems from thermal overloads. In this system thermal sensors are directly attached to coils and are electrically connected to other components through isolation transformers. The response time of the interlock system is estimated to be less than 1.5 seconds.

ISSN:0034-6748    

DOI:10.1063/1.1136163

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple circuit is described which when added to a commercial KEITHLEY electrometer (Model 610C) enables the instrument to be used for carrying out current–voltage measurements with any known and constant current, in the range 10−12–10−5A, passing through a specimen and with up to 100 V dropped across it.

ISSN:0034-6748    

DOI:10.1063/1.1136164

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An easily constructed device is described that ensures deformation‐free electrolytic etching of thin (&mgr;m range) specimens and avoids elaborate and time‐consuming procedures. Essentially the device consists of a perforated electrode on which the specimen is held by maintaining a low pressure underneath. In addition the description of a valve assembly is given which is used for the recycling of the electrolyte that is sucked out of the bath through the holes in the electrode.

ISSN:0034-6748    

DOI:10.1063/1.1136134

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple, digital, waveform‐averaging circuit is described for measuring very weak light signals by use of photon counting technique. The maximum time resolution of the circuit is 1.5 &mgr;s.

ISSN:0034-6748    

DOI:10.1063/1.1136135

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An interface is described which permits high‐speed wordwise data transfer between a Biomation 820 Transient Recorder and a MINC (LSI‐11/2) minicomputer. Using a DRV11‐B direct‐memory access card, up to 50 full 2 K records/s can be transferred to the MINC system; single word control data can also be passed from the computer to the Transient Recorder.

ISSN:0034-6748    

DOI:10.1063/1.1136136

出版商:AIP    

年代:1980

数据来源: AIP