High-speed Oscillograph Research Articles

In Memoriam: Marvin A. Van Dilla: 1919-2019.

© 2020 International Society for Advancement of Cytometry.

Automated System for Control of Wave Impedance of the Delay Lines Controlled by PC

There is described automated system controlled by PC for measurement of wave impedance of the delay and deflection systems. High speed oscillograph C1-91 is used in the system and connected to PC through universal driving system for automated experiment CAMAC. Significant influence on the measurement result accuracy is made by alteration of the parameters of the vertical ray deflection amplifier of the oscillograph. There is experimentally confirmed that measurement accuracy increases by average calculation of few single measurements.

Hydrodynamic Stability and Thermal Performance Test of a 1-MWt Sodium-Heated Once-Through Steam Generator Model

The 1-MWt Heat Transfer Model (HTM-1) test program was directed to the development of techniques to predict, and thereby avoid, water-side instabilities in sodium-heated once-through and recirculating steam generators. Water-side performance instabilities in steam generators have been an underlying problem through decades of experience. This subject is of particular concern to sodium-heated units due to the severe performance deterioration that can result from such instability. The 1-WMt test model contains nine 0.50 in. OD 130 ft long serpentine tubes. Thermocouples and low-pressure-drop orifice flow meters were installed at the feedwater inlet end of each of the three active tubes to disclose instabilities. These measurements were recorded on a high-speed oscillograph. Instabilities were deliberately induced in order to determine the inception condition of instability. The model was dynamically stable for a range of operating conditions. The model was statically stable (uniform static feedwater flow distribution) at all steam outlet conditions tested. The model was generally more stable than predicted especially at higher loads.

High Frequency Recording with Electrostatically Deflected Ink Jets

A high speed oscillograph, using ordinary ink and paper, has been developed that provides a new approach to the old problem of producing instantly visible, high frequency records with inexpensive writing materials. A high speed jet of ordinary fountain-pen ink is divided into a uniform procession of drops, each of which is independently charged in proportion to an input-signal voltage. After projection through a constant transverse-deflecting field, the charged drops are collected on a moving chart to form an instantly visible, permanent record of the input signal. Drops are typically formed at a rate of 100 000/sec; each has an independent trajectory and makes an individual mark representing an independent sample of the input waveform. The ink stream may be switched on or off at high speed by providing, between the drop-launching point and the record surface, a collector that intercepts drops having a specific trajectory. Besides oscillography, which is discussed in detail, the technique has applications in other fields requiring marking at high speed or marking without pressure or physical contact.

The Spectral Distribution of some Optical Radiation Phenomena in Arc Conduction Pulses in Low Pressure Inert Gases†

ABSTRACT Using a set of narrow-band spectrum filters and an electron-multiplier photo valve combined with a wide-band amplifier and a high-speed oscillograph, the spectral distribution was obtained of the radiation intensity resulting from plasmas produced on the discharge of a charged capacitor of varying capacitance and voltage through cold-cathode arc conduction valves filled, respectively, with Ne, Xe and Kr at a low pressure, and the oscillograms have been analysed in respect of the spectral distribution of the effect of changing the energy discharged through a valve. A distinct afterglow is present in the radiation from the Ne plasma, but is absent in those from Xe and Kr, and radiation intensity humps appear in the afterglow of the Ne plasma, and on the declining branch of the main glow of the Xe and Kr plasmas when the energy discharged through the valve is sufficiently increased, these humps indicating the occurrence of some specific additional recombination processes in the respective plasmas.

Rapid Geomagnetic Fluctuations

The article presents an investigation of VLF-oscillations (0.2–200 c/s) in the earth's magnetic field. The measurements were made in the archipelago of Stockholm (59° N) during the period July 1957—June 1959. The oscillations were recorded by two different instruments: a high-speed Heiland oscillograph and a low-speed Esterline-Angus recorder. In the Esterline-Angus diagrams a morning minimum at about 8 o'clock local time was found. In the Heiland oscillograms three different features were found: 1. Frequent occurrence of sinusoidal fluctuations presenting a few very narrow bands; 2. Oscillations in the H- and Z-component are sometimes simultaneous, sometimes not; 3. The amplitudes in the Z-component are smaller than in the H-component. It has not been possible to find a correlation between the fluctuations investigated here and other geophysical phenomena. A possible mechanism for generation of the sinusoidal oscillations is discussed. DOI: 10.1111/j.2153-3490.1961.tb00105.x

The screen efficiency of sealed-off high-speed-oscillograph cathode-ray tubes

The factors which affect the screen efficiency of a high-speed oscillograph cathode-ray tube are summarized, and the nature of the shape of the luminance pulse produced by a short-duration square-wave screen excitation is explained. It is then shown how shortening the duration of screen excitation reduces the screen efficiency of the tube as a consequence of energy lost by non-radiative dissipation.

The coaxial-line diode: a rectifier of microwaves

The coaxial-line configuration of the diode is shown to provide a non-linear radial field and a long interaction path. These two features contribute to the relatively high detection efficiency of the device when operating at high microwave powers. At the signal levels at which it is usefully employed the low-signal theory does not apply. The theory which is discussed shows that electronic transit times are equal to several cycles of the microwave field. It also shows that some electrons which are caused by the negative phase of the microwave field to back-bombard the cathode play an important part in the process of rectification. The microwave power range in which the coaxial-line diode is employed is from 100 watts to 100kW. Its operation at these high power levels provides sufficiently high output voltages to produce useful deflections on normal high-speed oscillographs without intermediate amplification. It thus provides a direct and reproducible method of measuring peak microwave power and of observing magnetron pulse forms with high resolution. The inherent resolution is limited only by the self-capacitance and output impedance (both of which are low) and by the transit times of electrons in the diode. Resolutions of up to 10 -8 sec have been obtained. Coaxial-line diodes have been operated at frequencies from 3000 to 35000 Mc/s. In the process of rectification several harmonics are produced. The dimensions of the diode are not limited by the transit time of electrons in the microwave field; consequently the valve is easy to construct and does not involve unusually small electrode spacing.

The ultimate performance of the single-trace high-speed oscillograph

The limitations to writing speed and deflection sensitivity of the single-trace high-speed oscillograph are analysed in terms of theoretical electron-gun performance and the spherical aberration of practical electron lenses. It is shown that considerable improvements over the best present-day designs are theoretically possible. The results indicate the design trends which should achieve the improved performance.

A RAPID-SCANNING AURORAL SPECTROMETER

A spectrometer is described which is capable of obtaining an auroral spectrum in 10 sec. with 10 Å resolution. It uses a 4 by 4 in., 6000 lines/cm. grating and parabolic mirrors for focusing. The detector is a 1P21 photomultiplier cooled by dry ice, and the spectrum is recorded by a high-speed magnetic oscillograph. The amplifiers are described and a few sample spectra shown. Some relevant optical equations are collected in an appendix.

Some special oscillograph techniques

The paper gives a general classification of the types of transient phenomena that are of major importance in heavy current engineering, and require oscillographs for their investigation and recording. Such oscillographs are based upon the variety of high-speed tubes now available, and typical performance data are given for some of these tubes, and also for the electromagnetic and continuously evacuated oscillographs that represent the extremes of performance.The particular equipments described include a continuously evacuated oscillograph, high-speed oscillographs with sealed-off tubes, multiple recording on a high-speed drum equipment, a recurrent surge oscillograph, and a recovery voltage indicator. In many applications the oscillograph has to be considered as an integral part of the test circuit, and reference is made to some of the major problems of technique that are involved in such cases.

Aircraft radio interference measurements

For radio interference studies covering a wide frequency range, evaluation of the noise levels requires a great number of measurements with different instruments for each frequency range and type of communication. A high-speed oscillograph is valuable in such work as it can show the effect of each suppressive device on the undesirable transient.

Aircraft radio interference measurements

IT IS essential to know the wave shapes and statistical distribution of impulsive interference transients for working out adequate interference-reduction methods. Interference pulses such as are produced by corona and sparking phenomena in electric equipment present a serious problem in measurements. Conventional noise meters convert any kind of pulse to the same fundamental shock excitation wave shape determined by the characteristics of the initial circuits and thus the original character of pulses is masked. The noise meter is useful in assisting in the routine elimination of noise from various electric devices, for it informs the investigator of the progress made and it indicates when the noise is of such a character that it will no longer cause appreciable disturbance in a typical receiver. However, for interference studies covering a wide frequency range, evaluation of the noise level requires a vast number of laborious measurements with different instruments for each range of frequency and type of communications. When evaluating atmospherics or other interference that changes character with time, noise meter measurements cannot be made quickly over a wide frequency range. Thus for a fundamental study of the nature of interference, the oscillograph provides more useful information. A highspeed oscillograph is of value even in routine suppression tests, since it can show the effect of each suppressive device on the undesirable transient graphically.

A high speed transient recorder

The paper describes how the design of a high-speed oscillograph may be modified to produce a near-linear recordable sweep of 10-8 sec duration. The techniques necessary to reproduce photographically single transients of this order are discussed.

A high-speed recording oscillograph

The Oscilloscribe is a high-speed oscillograph which makes ink records on a fast-moving chart of voltages having frequency components ranging from direct current to 200 cycles per second. The basic element of the instrument, which is actually a servomechanism, is a D'Arsonval meter movement with no restoring springs.

A high-speed direct-writing oscillograph

THE Oscilloscribe, developed in the Servomechanisms Laboratory of the Department of Electrical Engineering, Yale University, is a very high-speed direct-writing oscillograph which produces an immediate permanent record of voltages having frequency components ranging from direct current to 200 cycles per second. Development of this device was started in February 1947 when comparable devices were not available commercially. Since that time several instruments of this general type have appeared on the market and have found a wide variety of applications.1

The Expansion of Gaseous Spark Channels

A rotating mirror camera with a temporal resolution on the film of 1.5 mm/μsec. has been used to determine the rate of expansion of long gaseous spark channels during their first 10 μsec. of growth. The spark channels conducted aperiodic impulse currents in the range of 60 to 500 amp. peak, which attained their peak values in about 1/4 μsec. and decayed to half-value in 10 or 28 μsec. Sparks have been investigated in air at atmospheric and reduced pressures, and in nitrogen, oxygen and hydrogen at atmospheric pressure. The measured areas of cross section of these spark channels bear a linear relation to the peak currents, except in hydrogen, and are little influenced by the rate of current decay in the range studied. Measurements have also been made with the rotating mirror scanning an image of the spark across a photomultiplier connected to a high speed oscillograph; by this method a direct record is obtained of the radial light distribution across the spark channels. The mechanism of spark channel expansion is discussed, and estimates are made of the average ion densities in spark channels.

The Design of a High-Speed Oscillograph

The principal design requirements of a high-speed oscillograph are described and the range of time-base speeds considered is 10-5 to 10-7 sec. Performance is illustrated by `single-stroke' and repetitive oscillogram records.

The recording of optical transients

Four methods of recording the transient optical phenomena associated with the spark breakdown of gases are described in the paper. The duration of such transients may vary between the limits 10−3 sec down to 10−8 sec. The consequent problems, limitations and characteristics of the methods are discussed, so that their application to the recording of similar optical phenomena may be appreciated.The first two methods of recording are direct photographic techniques which make use of the Kerr cell and the rotating-mirror camera respectively. The third method described is an indirect one, in which a photo-multiplier tube is used to convert the optical transient to an electrical one; the latter is then displayed on the screen of a high-speed oscillograph and photographed. This method makes use of a sealed off cathode-ray tube which has a 9-cm screen and is operated from a 10-kV supply. The design of the oscillograph and the associated photo-multiplier and amplifier circuits are described and oscillograms are included to illustrate the performance of the equipment. In the latter part of the paper, a recording technique is considered, which is based on the application of television techniques to this work. The principles of the method, which makes use of an iconoscope type of tube, are stated.

The design of high-speed oscillographs

Low-speed cathode-ray oscillographs are widely used for examining voltage waveforms in all branches of electrical engineering, and they are now familiar and generally accepted instruments. The special oscillographs designed for examining rapid transients were little used before the war, but radar research required reliable instruments for examining very short pulses. This paper outlines the difficulties which must be overcome in designing a high-speed oscillograph, and describes the characteristics required in the time-base generator, the cathode-ray tube and the signal-input circuits. The limitations of present instruments at the very highest writing speeds are enumerated, and possible remedies are suggested.