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Showing papers in "International Journal of Electronics in 1962"


Journal ArticleDOI
TL;DR: In this paper, a linear time and state dependent approximation to a non-linear and non-stationary system is optimized with respect to a quadratic performance index by treating it as an instantaneously linear stationary system.
Abstract: A linear time and state dependent approximation to a non-linear and non-stationary system is optimized with respect to a quadratic performance index by treating it as an instantaneously linear stationary system. By allowing for the variations of the model a realizable adaptive typo of controller can be devised.

166 citations


Journal ArticleDOI
TL;DR: In this paper, the cyclotron modes were found to be purely transverse electric at cut-off, gradually changing in character along their propagation curves through hybrid to purely transversal magnetic modes at cyclotic resonance.
Abstract: In the analysis of the waves which propagate in a waveguide completely or partially filled with a stationary plasma column or an electron beam drifting with a uniform velocity and collimated with a magnetic field of finite magnitude, it is necessary to include the effects of the rotation of the electric field in order to treat the waves which have phase velocities comparable to or greater than the velocity of light. Certain interesting features of perturbed waveguide modes and cyclotron modes become apparent only when the dynamic nature of the electric field is recognized in the analysis. These features are the influence of cyclotron frequency and the polarization of waves on the propagation characteristics. The cyclotron modes are found to be purely transverse electric at cut-off, gradually changing in character along their propagation curves through hybrid to purely transverse magnetic modes at cyclotron resonance. A classification of modes of propagation is proposed, and formulae for cut-off f...

86 citations


Journal ArticleDOI
TL;DR: In this paper, a shoot electron beam in a fictitious focusing field regarded as purely electric in a frame moving with the electron is analysed in terms of a model in which the phase space density changes in discrete steps at certain contour lines in the phase plane.
Abstract: A shoot electron beam in a fictitious focusing field regarded as purely electric in a frame moving with the electron is analysed in terms of a model in which the phase space density changes in discrete steps at certain contour lines in the phase plane. The equilibria and the eigenvalues for small perturbations in the case of a single contour are worked out. The advantage of this technique is that the only significant motions are those of the contour itself, the phase fluid inside being incompressible and homogeneous.

68 citations


Journal ArticleDOI
TL;DR: In this paper, it is pointed out that in many situations, including adaptive ones, it is still possible to compute an optimal control even with both observational and non-observational restrictions.
Abstract: Optimal control theory usually assumes that the state vector components of the controlled object can be measured exactly. However, practical measuring instruments frequently give significant error; also it is often impossible to monitor each component of the state. It is pointed out that in many situations, including adaptive ones, it is still possible to compute an optimal control even with both observational restrictions. Some simple examples are presented to illustrate the methods. These examples lead to a useful extension of the Certainty Equivalence Principle. These methods give an approach to the fundamental problem of partial observability, which is to say what kinds of observational restrictions allow effective controllers to be devised. Some tentative remarks are made about this.

47 citations


Journal ArticleDOI
TL;DR: In this paper, a simple regulator having an unknown gain in the control path is considered, and information on the unknown gain can be obtained only by using the control as a probe, and an optimal estimation procedure is presented.
Abstract: A simple regulator having an unknown gain in the control path is considered. Information on the unknown gain can be obtained only by using the control as a probe. An optimal estimation procedure is...

45 citations


Journal ArticleDOI
TL;DR: An analogue of Pontrjagin'maximum principle is presented for systems described by difference rather than differential equations, which should have application in the synthesis of sampled data control systems and in the design of chemical processing systems where the describing equations proceed stage by stage in space along a cascade.
Abstract: An analogue of Pontrjagin'maximum principle is presented for systems described by difference rather than differential equations. This discrete alogrithm should have application in the synthesis of sampled data control systems, as well as in the design of certain chemical processing systems where the describing equations proceed stage by stage in space along a cascade rather than step by step in time.

33 citations


Journal ArticleDOI
TL;DR: In this paper, the three methods of using a resonant cavity for microwave spectroscopic measurements, in terms of sensitivity and the ability to discriminate between absorption and dispersion, are discussed.
Abstract: The paper discusses the three methods of using a resonant cavity for microwave spectroscopic measurements, in terms of sensitivity and the ability to discriminate between absorption and dispersion. The experimental results obtained confirm this analysis. The theory for the equivalent modes of waveguide cell operation is also derived and is extended to the travelling-wave helix which is now beginning to be used in double-resonance spectroscopy.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the multiplication of carriers generated in the space charge layer of reverse biased silicon pn step junctions has been calculated in terms of multiplication of electrons and holes injected into the junction.
Abstract: The multiplication of carriers generated in the space-charge layer of reverse biased silicon pn step junctions has been calculated in terms of the multiplication of electrons and holes injected into the junction. Curves are plotted for p+n and n+p junctions, and good agreement has been found with experimental curves.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the design, advantages and applications of automatic electron diffractometers are discussed with reference to an improved system, including servostabilization of the gun emission, automatic two-dimensional scanning, and control of CRT display brightness or of xy writing rate in accordance with the intensity of the peaks.
Abstract: The design, advantages and applications of automatic electron diffractometers are discussed with reference to an improved system. The power to measure electron scattering profiles from which loss electrons are virtually eliminated is the fundamental difference between the new instruments and traditional photography of electron diffraction patterns. The basic limitations of the diffractometers are discussed. A new treatment of the electron gun is given, based on angular distributions of current which prove to be Gaussian. The treatment is necessary when maximum signal intensity is required. A number of improvements in electronic circuitry are described which include servostabilization of the gun emission; automatic two-dimensional scanning, and control of CRT display brightness or of xy writing rate in accordance with the intensity of the peaks. The fields of application where the now diffractometers have advantages are when accurate, that is filtered, intensities must be determined, and when grow...

18 citations


Journal ArticleDOI
TL;DR: In this article, Pontryagin's maximum principle was applied to the design of control systems with optimum transient response (OTR) for two simple examples in which there is a bounded constraint on the control signal.
Abstract: Pontryagin's maximum principle may be applied to the design of control systems with optimum transient response. An analogue computer has boon used to determine the optimum control for two simple examples in which there is a bounded constraint on the control signal.

14 citations


Journal ArticleDOI
TL;DR: In this article, the static analysis of the RvNR structure is presented and gross deviations from the expected " ohmie " behaviour are present, and the analysis proceeds by assuming the total current density is a known solenoidal vector.
Abstract: This paper presents the static analysis of the RvNR structure and shows that gross deviations from the expected ‘ ohmie ’ behaviour are present. The analysis proceeds by assuming the total current density is a known, solenoidal vector. From this and the necessary boundary conditions, the excess carrier concentrations and the terminal voltage are calculated. Experimental results are given, and are found to be in excellent agreement with the theory.

Journal ArticleDOI
TL;DR: In this article, various typos of low-pass filters which may be implemented in circuits involving only RC components and feedback amplifiers are considered in comparison with filters designed by optimization of pass-band characteristic purely on the basis of a minimum-mcau-square-error criterion.
Abstract: The various typos of low-pass filters which may be implemented in circuits involving only RC components and feedback amplifiers arc considered in comparison with filters designed by optimization of pass-band characteristic purely on the basis of a minimum-mcau-square-error criterion. A basic requirement observed in the optimum design is that the filter transfer functions shall be physically realizable in stable networks. The design restriction which is imposed when simplification of filter circuitry is attempted is considered in relation to a particular circuit.

Journal ArticleDOI
TL;DR: In this article, an analogue experiment was devised to study the conditions for the equilibrium of dense plasma cores contained by r.f. cavity fields, and the measurements were interpreted by use of the Wien-Ehrenfest adiabatic theorem to yield information on equilibrium of the core.
Abstract: An analogue experiment has been devised to study the conditions for the equilibrium of dense plasma cores contained by r.f. cavity fields. Plasma cores are simulated by copper spheres, spheroids and other configurations. Frequency shifts that result from finite perturbations in (1) size, (2) position and (3) configuration are measured. The measurements are interpreted by use of the Wien-Ehrenfest adiabatic theorem to yield information on equilibrium of the core. Measurements indicate that cores in a spherical cavity are in stable equilibrium against all three types of perturbation only in the magnetic quadrupole mode and in higher order magnetic multipole modes of the cavity fields.

Journal ArticleDOI
TL;DR: The positive and negative ions formed by electron impact in perfluoromethyl cyclohexane have been studied in a mass spectrometer as mentioned in this paper, showing that the most abundant positive ion CF3+ is in agreement with other studios, as is the appearance potential of this ion.
Abstract: The positive and negative ions, formed by electron impact in perfluoromethyl cyclohexane, have been studied in a mass spectrometer. The observation of the most abundant positive ion CF3+ is in agreement with other studios, as is the appearance potential of this ion. Seven negative ions, the most abundant of which is the parent ion C7F14–, have been observed and possible mechanisms for their formation are discussed.

Journal ArticleDOI
TL;DR: In this paper, an experimental study has been made of the poisoning of the thermionic omission from thoriated tungsten cathodes by oxidizing gases, and it has been shown that rapid poisoning takes place when a critical partial pressure is exceeded.
Abstract: An experimental study has been made of the poisoning of the thermionic omission from thoriated tungsten cathodes by oxidizing gases. It is shown that rapid poisoning takes place when a critical partial pressure is exceeded. For a fully carburized cathode this critical pressure measured, using an omega-tron mass spectrometer, is as follows: O2 10−5torr, CO2 2·0 × 10−5 torr, and water vapour 6 × 10−6 torr. In the experiments the total pressures measured by ion gauge were considerably higher due to the formation of CO at the cathode surface, Ther esistance to poisoning depends almost entirely on the presence of carbon on the surface, and any decarburization lowers the critical pressure. For a truly uncarburized cathode the critical pressures are loss than 10−9 torr, only the arrival of fresh thorium at the surface counteracting the adsorption of the poisoning gas. It appears probable that in the past so-called uncarburized cathodes must have had a small amount of curbon in the surface.

Journal ArticleDOI
TL;DR: In this article, the waveguide properties of annular-shaped plasma columns in the absence of an external magnetic field are investigated, and the analysis of the structure shows several novel characteristics of the propagation system.
Abstract: The waveguide properties of annular-shaped plasma columns in the absence of an external magnetic field are investigated. The analysis of the structure shows several novel characteristics of the propagation system. The modes of propagation on an annular plasma column are surface-wave modes, one on the inner surface and one on the outer surface. The dispersion relations obtained from the field analysis is plotted, and it is shown that the inner surface wave is a backward wave. When a conducting cylinder is placed on one surface of the annulus one obtains single-mode solutions, since the other mode is shorted out by the conductor. It is shown that the surface waves in the presence of a conducting boundary also exhibit pronounced backward-wave characteristics. The dispersion curves for these propagation systems are plotted. (auth)

Journal ArticleDOI
TL;DR: In this article, the mechanism of thermionic omission from an impregnated dispenser cathode is shown in a sequence of photographs, and correlation to empirical processing data is established by displaying the corresponding physical phenomena, thus minimizing theoretical uncertainties.
Abstract: On the 21 in. diameter screen of a magnetic omission microscope the mechanism of thermionic omission from an impregnated dispenser cathode is shown in a sequence of photographs. Emission phases clearly reveal the difference between the first and subsequent heat activations. Correlation to empirical processing data is established by displaying the corresponding physical phenomena, thus minimizing theoretical uncertainties. Forced diffusion of barium at 1160°c is found to be necessary for starting full and patchless emission by continuous barium dispensation as well as an operating temperature somewhat below 1160°c for maximum life, stability, minimum evaporation and sublimation of barium The probability of retaining barium polylayers on the tungsten surface is evidenced by barium pool formations of long life which is well supported by theories on vapour and contact ionization in barium Matrix porosity, average pore diameter and pore separation are determined from the screen for future theoretical ...

Journal ArticleDOI
TL;DR: In this article, the effect of the well-known Lorentz term in the evaluation of the electron density in low-density plasmas is discussed in the context of microwave measurements.
Abstract: Microwave and Langmuir probe measurements were carried out simultaneously on the plasma of a low-pressure mercury-vapour are. The values of the average electron density, obtained by the two types of measurements, are in reasonable agreement. The effect of the well-known Lorentz term in the evaluation of the electron density in low-density plasmas is discussed in the context of microwave measurements. The method of Hoyaux for obtaining the space potential from the voltage-current characteristic for the Langmuir probe is confirmed.

Journal ArticleDOI
TL;DR: In this article, the effect of the anode aperture in conical flow Pierce guns is investigated by moans of first-order perturbation theory and various perturbations are computed for a gun which, according to Pierce's theory, has a perveance of 3·25 × 10−6.
Abstract: The effect of the anode aperture in conical flow Pierce guns is investigated by moans of first-order perturbation theory. Expressions are derived for the perturbation of the path, for the change in current density across the cathode and elsewhere across the beam, the loss in perveance, and the change in beam diameter and the focal length associated with the anode lens. The various perturbations are computed for a gun which, according to Pierce's theory, has a perveance of 3·25 × 10−6. Computed perturbations are compared with those obtained by experiment on a gun which was specially constructed to test the theory. There is good agreement between theoretical and experimental data.

Journal ArticleDOI
TL;DR: In this article, the relationship between the wall potential in low pressure gas diodes and parameters such as the gas pressure and composition, electron current and energy, has been investigated.
Abstract: The relationship between the wall potential in low pressure gas diodes and parameters such as the gas pressure and composition, electron current and energy, has been investigated. The results are found to compare favourably with a simple theory based on current balance conditions at the wall.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the slow surface wave propagation along the boundary of two diagonally anisotropic dielectric media (or bi-axial crystal) in a metallic cylindrical waveguide with an excitation by a magnetic ring source.
Abstract: Slow surface wave propagation along the boundary of two diagonally anisotropic dielectric media (or bi-axial crystal) in a metallic cylindrical waveguide with an excitation by a magnetic ring source is studied. The results of this general problem have been applied to study the wave propagation in plasmas in the presence of a zero or infinite uniform d.c. magnetic field in the axial direction. Numerical results have been obtained for these special cases. Although attention is directed towards the study of the slow surfaee wave propagation, the general expressions for fields and dispersion relation are valid for any possible mode of propagation in the structure. It is shown that for slow waves the axial component of one of the dielectric tensors must be negative.

Journal ArticleDOI
TL;DR: In this article, a modification of the technique suggested by Herinckx and Monfils has been used to measure the room temperature thermoelectric parameters of single crystal n- and p-type lead telluride over a range of carrier concentrations.
Abstract: A modification of the technique suggested by Herinckx and Monfils has been used to measure the room temperature thermoelectric parameters of single crystal n- and p-type lead telluride over a range of carrier concentrations. The Seebeck coefficient α, electrical conductivity σ (ohm−1 cm−1), and thermal conductivity K are related by the empirical equations : αn = 717 -181 log σn μv//deg, 500 < σn < 6000, αp= 702 - 187 log σpμv/deg, 200 < σp < 1700, K = 0.020 + 5× 10−6σ watt/cm/deg. n-type material has a maximum figure of merit at room temperature of 1-1 × 10−3 deg−1 when σn= 750 and p-type of 1 ×10−3 deg−1 when σn = 550. Comparison of the results with theory suggests that the charge carriers are scattered by the acoustical modes of vibration of the lattice and that the effective mass ratio is 0-25 for electrons and 0-35 for holes. Consistency between the theoretical calculations of Seebeck coefficient and thermal conductivity can be obtained if it is assumed that the lattice thermal conductivity i...

Journal ArticleDOI
TL;DR: In this article, an alternate formulation of the endpoint control problem that aims in the first instance at a feed forward control schedule is presented, although it can in principle be used to obtain feedback control policies as well.
Abstract: The endpoint control problem for noisy systems, as formulated in terms of dynamic programming (Bellman 1957), loads to a control policy which requires complete feedback information at every time when control action is to be taken The problem formulation applies conceptually only to systems making discrete jumps at discrete times, although the functional equations solution can in certain cases (in particular where the random disturbances to the system equations appear as an additive Gaussian white noise) be taken to the limit of continuous time (Florentin 1961) The present work investigates an alternate formulation of the problem that aims in the first instance at a feed forward control schedule, although it can in principle be used to obtain feedback control policies as well The policies obtained in this way differ in general from those arising from the formalism of dynamic programming This formulation applies equally well to systems evolving continuously in time, and, under certain restrictiv

Journal ArticleDOI
TL;DR: In this article, it is shown how to express the self-inductance of a wire loop in terms of the mutual interactions of the currents flowing in the filaments which constitute the conductor.
Abstract: It is shown how to express the self-inductance of a wire loop in terms of the mutual interactions of the currents flowing in the filaments which constitute the conductor. The connecting formula explains the dependence of self-inductance on material homogeneity and current distribution, while its dimension remains length. In the case of a homogeneous wire, long compared with its cross section and carrying a uniformly distributed current, the self-inductance is found to be equal to the average mutual inductance of all filament combinations. Considerable difficulties are encountered when trying to assign a numerical value to the self-inductance of an infinitely thin conductor filament. Any value, including zero and infinity, appears to fit the experimental facts. Greatest simplicity is obtained by assuming a zero value, which reduces self-inductance to a lumped parameter and implies that all forms of electromagnetic current generation are duo to mutual induction, as first suggested by F. E. Neumann.

Journal ArticleDOI
TL;DR: The literature on this type of optimum control is listed chronologically up to 1961 in this bibliography which totals 326 items as discussed by the authors, with partial and provisional information provided by the authors.
Abstract: When the plant (main process, controlled object) of a control system is specified by known differential equations, and the controller is subject to known constraints (especially saturation, physical realizability) it is often possible theoretically to design the controller so as to minimize some given performance criterion. The optimum controller usually turns out to be an instantaneous non-linear function of certain phase coordinates (state coordinates). Literature on this type of optimum control is listed chronologically up to 1961 in this bibliography which totals 326 items. The bibliography is partial and provisional.

Journal ArticleDOI
TL;DR: In this article, a straightforward procedure is derived for finding the extreme input which maximizes the output of a given system, for the ease of which only the bounds on the magnitude of the input and on its first derivative are specified.
Abstract: A straightforward procedure is derived for finding the extreme input which maximizes the output of a given system, for the ease whore only the bounds on the magnitude of the input and on its first derivative are specified. The synthesis problem is also treated wherein for this class of inputs the optimum system response function must be chosen to satisfy requirements on the maximum value of the system output.

Journal ArticleDOI
TL;DR: In this article, it was shown that the Lorentz polarization term should not be present in the expression for the dielectric coefficient of a plasma, and an experiment is described which indicates that the term should be removed from the expression.
Abstract: An experiment is described which indicates that the Lorentz polarization term should not be present in the expression for the dielectric coefficient of a plasma.

Journal ArticleDOI
TL;DR: In this paper, the beam loading of the equivalent current and the electron motion in a high frequency gap was derived using previously derived formulae for equivalent current (Warnocke and Guenard 1951) and for electron motion (Solymar 1961 b) in high frequency gaps.
Abstract: Using previously derived formulae for the equivalent current (Warnocke and Guenard 1951) and for the electron motion (Solymar 1961 b) in a high frequency gap, the beam loading is calculated. The solution is valid both for large space charge and large modulations up to the point when electron overtaking occurs. The weak space charge and small signal theories are contained as limiting cases. The dependence of the admittance on space charge and modulation index is demonstrated in a. number of graphs.

Journal ArticleDOI
TL;DR: In this article, a potential well is created between the beamemitting electrodes to trap a fraction of the beam electrons and accelerate the rest of them, and the burst occurs when the electrons are trapped in the well.
Abstract: Beam bursting was produced with two independent oppositely directed electron beams which interperetrated. The directed energy is converted into fluctuation energy. This occurs when the beams are injected, with low velocities, into a potential well caused to exist between the beamemitting electrodes. In the well, acceleration of the beam electrons and a trapping of a fraction of them takes place. Beam bursting can be produced only with such gas densities, and only in gases with sufficiently low electron temperatures, that standing waves of longitudinal electron oscillations can be excited. Particular combinations of beam currents and well potentials are required. The bursting phenomenon and the electron oscillations occur together. With critically adjusted conditions, tunable ion-oscillation frequencies can be excited; simultaneously the electron oscillations fall to a very low value.

Journal ArticleDOI
R. Esposito1
TL;DR: In this article, a two-port model is proposed for the analysis of noise in nonlinear oscillators and a systematic procedure is given for the evaluation of the output spectrum in the case of a zero-memory nonlinearity with an arbitrary narrow-band filter.
Abstract: A two-port model is proposed for the analysis of noise in nonlinear oscillators. A systematic procedure is given for the evaluation of the output spectrum in the case of a zero-memory non-linearity with an arbitrary narrow-band filter The a.m. and f.m, noise components are shown to be gaussianly distributed, at least for a gaussian driving noise but statistically independent only if the narrow-band filter has a symmetric shape around the oscillating frequency The method of analysis uses a describing function approach to the non-linearity and can be considered an extension of existing techniques A simple example is worked out in detail and agreement with previous calculations is shown.