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The paper deals with parametric phenomena in a non-linear oscillating circuit with negative resistance. The differential equations of the parametric excited circuit, for the case where the self-oscillations' amplitude is smaller than the amplitude of the pumping signal, reduce to the equations of Hill and are solved by an original method (Samoylo and Spasov 1970). In an investigations of the transient and steady-state regimes the real non-linearity of the reactive element in the oscillating circuit is considered. The mode of forced oscillations and the resonance of the second and third subharmonics of the pumping signal are discussed. The experimental results agree well with theory.
The results given in the paper may be of interest in an investigation of oscillating circuits, utilizing semiconductor elements with negative resistance : tunnel diodes, Gunn diodes, avalanche transit-time diodes, etc. [ABSTRACT FROM AUTHOR]

In the present paper eigen-frequency of electronic damped oscillations in a plasma is derived. These oscillations are, however, not sustained. Further sustained electronic damped oscillations in the plasma in the presence of an external electric field are analysed.
Eigen-frequency of electronic damped oscillations in a plasma is derived in this paper. It is the intrinsic tendency of damped oscillations in the presence of local fields between charges of the plasma. These oscillations are, however, not sustained as such in practice. But if an electric field E be applied to the plasma model, sustained electronic damped oscillations result which are analysed here. [ABSTRACT FROM AUTHOR]

In the previous papers (Bhagavat and Nandedkar 1988, Nandedkar and Bhagavat 1969) investigation of r.f. energy transport in the vicinity of damped oscillations in plasma, where absorption of r.f. energy is maximum, is carried out. Backward waves are shown to exist in the region of anomalous dispersion of the plasma. The absorbed r.f. energy in the region of backward waves appears as noise.
In the present paper, wavefront and signal velocities of a r.f. wave in plasma, in the region of backward waves are analyzed
Whatever may be the frequency of a r.f. wave, the velocity of wavefront in plasma, is always equal to the velocity of a T.E.M. wave in free space (eqn. (19)). Thus the wavefront velocity in the region of backward waves is equal to the wave velocity in free space. When the wavefront of the signal makes its way through the plasma, it finds the electrons which are capable of oscillating originally at rest. Originally, therefore, the plasma seems to be free space for the electromagnetic field propagation; only after the electrons are set into motion, can influence the phase and form of the electromagnetic wave. The propagation of wavefront thus proceeds undisturbed with the velocity of a T.E.M. wave in free space; independently of the character of oscillating electrons.
Figures 13 anti 14 show that the signal velocity for < increases with the increase of the frequency of the r.f. wave, in the region of backward waves (for backward wave region, refer to Bhagavat and Nandedkar 1968e). In this portion of the region v is less than c. At = the signal velocity becomes equal to the velocity of a T.E.M. wave in free space. For > the signal velocity decreases with increase of frequency; in this portion of the region, v is again smaller than c. The left half portion of the region of backward waves with respect to is a mirror image of the right half portion. One thing... [ABSTRACT FROM AUTHOR]

In the previous papers (Bhagavat and Nandedkar 1968 b, c, d) the investigations of the damped oscillations and velocity of energy transport of a r.f. wave in a plasma in the region of anomalous dispersion were made.
This paper covers the analysis of phase and group velocities of a r.f. wave in this region. This analysis indicates the existence of backward waves which are experimentally verified. [ABSTRACT FROM AUTHOR]

In a previous paper (Bhagavat and Nandedkar 1968) an analysis of the frequency of damped oscillations in the presence of a r.f. field in a plasma model in equilibrium was made.
This paper makes a complete analysis of this subject in the presence of a d.c. field. An experimental investigation of the variation of with the electron density and a d.c. field is described. [ABSTRACT FROM AUTHOR]

Extensive studies have been made of instability in two counter-streaming low-voltage electron beams in a low-pressure plasma. Estimates from dispersion theory of the critical conditions at which oscillations should begin have been found to agree with experiment. The study of the advanced stages of instability, which are associated with ion and electron oscillations, indicates that a transition has then occurred to turbulence, using this term in a generalized sense. This paper (I) deals with the onset of instability. A second paper (II) will deal with the turbulent rgime. ABSTRACT. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of pulse circuits composed of a tunnel diode and a transmission line. The method employed, analysis in the v-i plane, is applied to the self-oscillation mode as well as to that of the one-shot mode. Effects of load and source (bias) impedance, linear and non-linear, are investigated. The analysis of non-linear biasing leads to configurations which present an improved triggering ability, shorter recovery time and less sensitivity to bias voltage variations. [ABSTRACT FROM AUTHOR]

Oscillation amplitude in a negative resistance (NR) oscillator is usually evaluated by the describing function approach in which the non-linear v-i characteristic of the NR device is approximated by a few terms of a power series expansion. But quite often when Negative Impedance Converters are used to simulate NR, a piecewise linear and symmetric v-i characteristic results. The present paper exploits the above mentioned linearity and symmetry to obtain, to a first-order approximation, a universal curve for determining the oscillation amplitude.
The almost sinusoidal oscillation of a negative resistance (NR) device when connected to a resonant LC circuit is a well understood phenomenon. The first-order solution for the oscillation amplitude can be theoretically determined by the describing function approach (Strauss 1960). This method involves approximating the non-linear device characteristic by a few terms of a power series expansion about the quiescent point. However, when Negative Impedance Converter (NIC) circuits are used to simulate NR, very often a piecewise linear and symmetric curve results. This linearity and symmetry can be exploited to obtain a better accuracy than can be obtained by a power series approach. We employ such a method to analyse the oscillation amplitude in a current-inversion NIC(CNIC) oscillator and show that, to a first-order approximation, an analytic expression for the amplitude can be obtained. [ABSTRACT FROM AUTHOR]

The characteristics of detected wave form, and output power of the oscillations of a Gunn diode, with an oscillation frequency of approximately 4 GHz mounted inside a coaxial type resonant cavity, at varied cavity lengths, were measured when the temperature was lowered from room temperature to -120degreesc.
Heat is generated when a Gunn diode is operated at relatively high output power. Generally, because of this heat, the quality characteristics of the diode get worse. That is why that the characteristics of the Gunn diode at higher temperatures, above room temperature, has practical importance and a relatively large amount of research has been done on it. On the other hand, we know that theoretically the output power and efficiency of oscillation in the diode increases gradually as the temperature decreases from room temperature. As far as we know, there are no reports or papers published concerning the low temperature characteristics of the Gunn diode. [ABSTRACT FROM AUTHOR]

Interaction of streaming electrons and low frequency electromagnetic waves, both confined to a geomagnetic tube of force, has been studied. Following Roberts and Buchsbaum's theory it, is shown that electron energy gain is oscillatory. Considering low energy (< l0 ev) electrons the time period of energy oscillation is found to be maximum at the equator for 15 kHz and increases with increasing frequency. For 15 100 kHz, the maximum time period of energy oscillation is found to be almost constant (5.3 l0sec) in the entire band of frequencies. The maximum time period shifts towards higher latitude with increasing frequencies, whereas, for high energy (100 keV) electrons the time period of energy oscillation increases with the increasing latitude and at high latitude (65) the time period is almost constant (0.98 l0 sec) for waves of different, frequencies. The energy gain is found to increase steadily with increasing latitude. Observed periodic geophysical phenomena have been interpreted in terms of calculated results and their significance has been discussed.
In the present paper we have studied the consequence of naturally generated electromagnetic waves interacting with the electron influx spiralling along the geomagnetic field lines. The outstanding feature of the interaction between electromagnetic waves and electrons in magnetoplasma is gyroresonance. [ABSTRACT FROM AUTHOR]

Low frequency oscillations associated with trap-controlled moving domains in high resistance semiconductors have been studied by a number of investigators. The mechanism involved is an increase of the capture cross section of a repulsive centre with increase in the applied electric field.
Although many of the features involved have been established by experimental studies, the modelling and analysis available have so far been incomplete. The present paper shows that computer studies can make a contribution to understanding of the domain behaviour and the effects of illumination.
Using a simple functional form for the capture coefficient of a repulsive centre in GaAs, the non-linear equation obtained can be shown to result in a dipole domain propagating with constant velocity for bulk material. The threshold for domain nucleation was 860 volts/cm. Domain velocities were found to increase with illumination level and applied voltage, and for the model considered ranged from 0.25 cm/sec in the dark to 125 cm/sec under illumination. The domain width increased with applied bias and varied from 0.05 to 0.15 cm. The domain consisted almost totally of fixed space charge, and was closely symmetrical in shape. [ABSTRACT FROM AUTHOR]

The paper describes a second-order non-linear system generating discontinuous oscillations. The system comprises a linear amplifier, a clipper and an L-C network connected in cascade and joined by an overall regenerative feedback loop. The mechanism of oscillation is analyzed and the expression for its time period is obtained. The same method of analysis is also extended to systems comprising more complicated L-C networks. The above circuits generate square wave voltages of constant amplitudes and frequencies variable over a wide range. [ABSTRACT FROM AUTHOR]

This paper describes a multivibrator with two widely different zones of discontinues oscillation. The circuit comprises an amplifier, a clipper and two differentiators with a large ratio of time constants connected in a regenerative mode. A silicon diode non-linearity is introduced in the first differentiating network, which causes the circuit to shift the zone of oscillation under certain conditions. The complete analysis and design consideration with full details of frequency determination are presented here.
The above method of analysis may be extended to study the behavior of similar systems with three differentiating networks having time constants , and ( ), the first two of which are biased with symmetrical non-linear resistances having threshold voltages V and V (V > V > V) respectively. The excursion of the system representative point over a cycle may be represented in a three-dimensional plane and the frequency of oscillation may be determined by a similar method. The dual-range multivibrator circuit is likely to find numerous applications in the field of instrumentation and remote control because of the facility of frequency control by an external signal. Used in conjunction with suitable filters, the circuit may work efficiently as voltage sensitive relays, and with simple modifications, it may be used in the field of pulse modulation. [ABSTRACT FROM AUTHOR]

By application of a strong constant voltage a semiconductor wafer may produce current oscillations or instabilities. This paper gives a small-signal analysis of a one-carrier semiconductor, assuming the equilibrium solution constant in space and time. The dispersion equation yields one electromagnetic mode and one carrier mode which are stable if the differential conductivity is positive. Both modes may co-exist in a wafer of the semiconductor. The amplitude ratio and phase difference between the two modes are represented by the complex parameter A/A, which depends on the boundary conditions. The natural resonance frequencies (which, generally, are complex) depend both on A/A and on the external load. For the short-circuit case, stability criteria involving A/A are developed. It is found that some of the resonances may be unstable even if the differential conductivity is positive. For most of the discussed eases, however, unstable resonances require a vanishingly small differential conductivity, that is, saturation in the drift velocity. [ABSTRACT FROM AUTHOR]

While generating very low frequency sinusoidal voltage, using operational amplifiers, one experiences difficulties in stabilizing the amplitude and every endeavour has been made to get a satisfactory solution. The paper describes one method by which stable oscillation can be obtained to a frequency as low as 0.01 c/s. The oscillator consists of two integrators and one sign changer interconnected in the form of a closed loop so as to solve a second-order differential equation. The amplitude is stabilized with the help of an extra stabilizing loop which consists of a squaring network. A brief analysis of the oscillator has been carried out and the precautions that have to be taken for improving the oscillator performance are discussed. [ABSTRACT FROM AUTHOR]

In a previous work the authors investigated the oscillations of the electron cloud in heavily cut-off split-anode small-cathode magnetrons whose segments were connected by a variable resistor. It was found that the simultaneously radiated oscillations could be divided into two groups originating in two spatially separated regions of the cloud.
In the present paper it is shown that, in accordance with the recently developed theory of the instability of crossed-field electrons beams, it can be reasonably assumed that two different kinds of instabilities are responsible for the oscillations considered. The first one is the resistive will instability of the near-anode layers. The second one seems to be the diocotron instability which probably takes place only in a thin layer of enhanced electron concentration, situated in the inner region of the cloud. [ABSTRACT FROM AUTHOR]