摘要:

Superheterodyne stimulus‐response measurements can be made with high dynamic range, but are often sensitive to oscillator frequency drift and noise. The usual techniques for reducing this sensitivity often become impractical at millimeter‐wave frequencies and above. This paper describes a feedforward tracking technique and its application to single frequency millimeter‐wave interferometry and Doppler‐shift scattering measurements on tokamak plasmas. Swept frequency transmission measurements can also be made with high dynamic range using this technique.

ISSN:0034-6748    

DOI:10.1063/1.1136209

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A miniature resonance absorption spectrometer is able to perform a routine monitoring in space of the line profile and intensity of the Heiresonance line from the solar disk with a time resolution of about 1 min and a spectral resolution of 105. It consists of a predispersive spectrometer incorporating a helium gas absorption cell. The instrument has been designed to meet a small size and weight. It was tested on a rocket flight in June 1976. The construction, principles of operation, and laboratory calibration of the instrument are presented. Its capability to resolve details of the order of 0.3 pm FWHM and its sensitivity to the intensity of line wings three order of magnitudes fainter than the peak of the line have been established by laboratory investigation.

ISSN:0034-6748    

DOI:10.1063/1.1136210

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

In multiple channel strip‐chart recorders the different graphs are always displaced due to mechanical shortcomings. An electronic device which compensates for that displacement has been developed and tested. This displacement correction unit is a necessity in applications where the information in the different channels are strongly correlated, which is the case in our work in high resolution laser spectroscopy. The use of highly integrated electronic components makes the circuit design straightforward and compact.

ISSN:0034-6748    

DOI:10.1063/1.1136211

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

In a Mo¨ssbauer effect spectrometer employing a large vibrating mass or stiff drive centering springs, it is sometimes difficult to achieve satisfactory velocity tracking. In such situations, the linearity and stability of a constant acceleration Mo¨ssbauer velocity drive can be improved significantly by inserting a correction signal into the feedback loop. A simple physical interpretation of a shape correction technique is discussed, and a drive amplifier using this principle is described. This system has less than 0.1% tracking error over the velocity range ±2 cm/s, yet the feedback gain is reduced by a factor of 60 as compared to a conventional drive.

ISSN:0034-6748    

DOI:10.1063/1.1136212

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An ammonia monitor has been made by using a rectangular Stark microwave cavity tightly coupled through an iris to a Gunn oscillator. The Stark electrode installed inside the cavity is provided with a 100 kHz sinusoidal modulation voltage and a dc sweep voltage. The oscillation of the Gunn diode is tuned with the coupled Stark cavity to a frequency near aJ,K=3,3 transition (23870.1 MHz) of ammonia. By fixing the Stark dc bias to a voltage which gives a peak intensity of the derivative output of the electric‐resonance signal, ammonia is continuously monitored. An extremely good long‐term stability is obtained. The noise level corresponds to 0.08 ppm of ammonia.

ISSN:0034-6748    

DOI:10.1063/1.1136213

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A two‐filter, continuous monitor has been developed for atmospheric222Rn. Features include a sensitivity of better than 0.01 pCi/l, a high specificity for222Rn, and immediate start up capability. The monitor has been computer modeled to facilitate calibration and selection of operating parameters. The filters are stationary and require no moving parts for control. Field trials indicate high reliability and maintenance‐free operation for periods of a week and longer.

ISSN:0034-6748    

DOI:10.1063/1.1136214

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We present the design and applications of a simple and very low‐cost digital events analyzer, suitable for use in a student laboratory as well as in research applications. The pulse analyzer can perform five functions: sampling measurement; pulse interval distribution measurement; simple triggered multichannel scaling; scaled triggered multichannel scaling; and auto‐ and cross‐correlation function measurement. The memory capacity is limited to 100 channels with 11 bits or more word length. The basic cycle time of the analyzer is 500 ns as limited by the speed of MOS circuit used. We demonstrate the utility of it with counting statistics experiments of radiations from radioactive decay, neutron time of flight analysis, and also the photon correlations measurements of light scattered from particles in fluids.

ISSN:0034-6748    

DOI:10.1063/1.1136215

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The design and construction of a multichannel Faraday cup detector and digitizer system for routine monitoring of ion emission characteristics from laser driven implosions are discussed. Experimental results are presented to demonstrate the operation of the device.

ISSN:0034-6748    

DOI:10.1063/1.1136216

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple and inexpensive device is described which in conjunction with conventional pulse echo equipment allows the direct measurement of the time interval between the zeros of selected individual cycles in different echoes with an accuracy better than 0.2 ns.

ISSN:0034-6748    

DOI:10.1063/1.1136217

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Small periodic variations in a main gas flow through a capillary are reduced from 1% to 0.1% in peak‐to‐peak width by a feedback circuit between a pressure gauge and a motor of a pump. The variations in flow result from nonlinear transmission of a worm mechanism in a capillary‐type closed viscometer, Dynamical properties of the system are discussed by the Laplace transform method, and it has been shown that low pressure, a long guide tube, and high gain of the amplifier are responsible for the flow instability.

ISSN:0034-6748    

DOI:10.1063/1.1136218

出版商:AIP    

年代:1980

数据来源: AIP