Fried, B. D.Overview
Publication Timeline
Most widely held works by
B. D Fried
Conversion of Electrostatic and Electromagnetic Waves in a Plasma at the Peak of a Parabolic Density Profile
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Book
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1 edition published in 1990 in English and held by 2 libraries worldwide Analytic expressions for the reflection, transmission, and mode conversion coefficients for electromagnetic and Langmuir waves in an unmagnetized plasma with a parabolic density profile are found for both the direct problem (incident electromagnetic wave) and the inverse problem (incident Langmuir wave). In contrast to the linear profile problem, the absorption depends explicitly on the value of collision frequency (cold model) or temperature (warm plasma), but a transformation of parameters relates the results for these two limits.
Cyclotron Resonance Phenomena in a Nonneutral Plasma
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Book
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1 edition published in 1987 in English and held by 2 libraries worldwide A kinetic theory of electrostatic cyclotron waves in a single component plasma slab of density n sub o(x) immersed in a uniform magnetic field B sub o z is presented. The space charge electric field Eo(x)x in such a plasma modifies the single particle gyrofrequency causing the upper hybrid frequency to have the value sq. rt. ((Omega sub 1) squared + (omega sub p)squared). Finite Larmor radius effects introduce a velocity dependence into the single particle gyrofrequency, leading to energy transfer to the particles located at the resonant layers. This energy transfer mechanism is operative even when sub f = O. Another nonzero Larmor radius effect is the appearance of thermal modes which are the analogs of Bernstein modes of neutral plasmas. When driven by an external capacitor plate antenna, these modes exhibit behavior similar to Tonks Dattner resonances.
Cyclotron Resonance in a Nonneutral Plasma
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Book
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1 edition published in 1985 in English and held by 2 libraries worldwide Single component plasmas are found to exhibit a reversal in the roles of cyclotron and upper hybrid resonances familiar in neutral plasmas. There is a global resonance at the cyclotron frequency omega = Omega = qB/mc and a local field cancellation at layers where omega = Omega sub 1 = sq rt(Omega-squared-(omega sub p) squared), omega sub p being the local plasma frequency. Thermal effects limit the amplitude of the global resonance and produce energy absorption at the omega = Omega sub 1 layers. (Author).
The Cauchy-integral root-findig method and the plasma "loss-cone" instability
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Book
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1 edition published in 1968 in English and held by 1 library worldwide
Cross-Field Current-Driven Ion Acoustic Instability
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Book
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1 edition published in 1971 in English and held by 1 library worldwide The report discusses the instability which occurs when electrons and ions have a relative streaming velocity, along x, V sub D> c sub s = square root of ((T sub e)/m), across a weak magnetic field, B sub Z. If (k sub x) (r sub c) mach> 1 and omega much <(omega sub ce), the spatial growth rate is enhanced by a factor K sub x/K sub z over the value at B sub z = 0. Measurements of growth rate (Im k/Re k) have been carried out in two different plasma configurations as a function of both B sub z and omega. The results are consistent with the linear dispersion relation for this instability. (Author).
Nonlinear Evolution and Saturation of an Unstable Electrostatic Wave
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Book
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1 edition published in 1971 in English and held by 1 library worldwide The nonlinear development and saturation of a single Langmuir wave driven unstable by a gentle bump in the tail of the distribution function in a collisionless plasma is studied by treating the resonant particles numerically. Over a wide range of parameter values, the amplitude of the potential Phi is found to saturate at such a level that the ratio g = Omega(b)/Gamma(0) approximately equals 3.2, where Omega(b)=/(e(k squared)Phi/m) is the bounce frequency of the trapped particles in the wave trough and Gamma (0) is the linear growth rate, approximately given by the classical Landau value. In view of the importance of inverse Landau damping for many instabilities, this work should have wide applicability and the results should be suitable for direct experimental tests. (Author).
Growth Rates of Parametric Instabilities Driven by Two Pumps
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Book
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1 edition published in 1984 in English and held by 1 library worldwide The parametric instability growth rate of ion acoustic and Langmuir waves, driven unstable by two uniform pumps near the Bohm-Gross frequency, is calculated as a function of pump amplitudes and frequencies. Two instability mechanisms can be identified: one corresponds to the usual, single pump parametric instabilities (decay and oscillating two stream) while the other is similar to that found in the Mathieu equation. The interaction between these two mechanisms results in a non-monotonic dependence of the growth rate on the pump amplitudes and frequencies: both cancellation and enhancement are obtained for various values of the parameters. An analytic study of the relevant dispersion relation using Hill's method is complemented by numerical studies in both the frequency and time domains. (Author).
High Altitude Plasma Effects
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Book
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1 edition published in 1973 in English and held by 1 library worldwide The principal results of the program to simulate ionospheric modification field experiments in the QUIPS device are reviewed. The main conclusions are: By linear mode conversion electromagnetic waves (EMW) propagating in the inhomogeneous laboratory plasma produced very intense electron plasma waves (EPW) (orders of magnitude above the EMW) propagating along the density gradient. Unanticipated by conventional theory, the linearly converted EPW was the lowest threshold pump of the parametric instability. In square wave operation, at the turn-off and turn-on of the EMW pump, the ponderomotive force due to the electrostatic field of the linearly converted EPW produced a large pulse of density perturbation, proportional to incident power (i.e., without threshold), which propagated away from the plane of reflection of the EMW.
Ionospheric Plasma Effects
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Book
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1 edition published in 1975 in English and held by 1 library worldwide During the first half of this contract, the following effects, related to ionospheric modification experiments were investigated: (1) Convective parametric amplification (improvement and exercise of a computer code yielding a theoretical parametric study of Arecibo spectral observations in qualitative agreement with measurements in restricted parameter domains); (2) Refraction by the pump of parametrically generated waves in both the laboratory and the ionosphere; (3) Double resonance excitation in a homogeneous plasma by infinite wavelength pumps in general and for laboratory and ionospheric applications in particular; and (4) Parametric instabilities driven by linearly converted pump modes.
The trw two-station, on-line scientific computer
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Book
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1 edition published in 1964 in English and held by 1 library worldwide This report describes the research and development of on-line techniques and their application to problem solving. For convenience, it is organized in several parts. Part 1 lists the published papers describing research problems solved in the course of this effort and summarizes the computational aspects of the multi-dimensional problem (a nonlinear diffusion equation) which received the most attention; the physical significance of this problem and a discussion of the results obtained is given in part 5. Part 2 contains a general description of the on-line system from the user's viewpoint, including some elementary examples of the 'constructive' aspects of on-line computing. In part 3 we have collected the on-line problem solving techniques developed in this program which are of general interest. These involve a blending of numerical and mathematical analysis somewhat different from that generally encountered in conventional computing, being best characterized as emphasizing a global rather than a local approach to problem formulation and solution. Part 4 constitutes a complete user's manual for the present system. It gives a detailed description of each of the basic programs. A general understanding of the on-line system can be obtained from part 2; parts 3 and 4 provide the detailed information needed to actually use this system. (Author).
Longitudinal plasma oscillations in an electric field
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Book
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1 edition published in 1959 in English and held by 1 library worldwide The properties of longitudinal plasma oscillations in an external electric field are investigated. In a completely linear approximation, it is found that the direct-current electric field introduces essentially no new effects. A quasi-linear approximation is also considered, in which couplings between different plasma modes are neglected while the space-averaged distribution functions are assumed to be approximately independent of time. In this case, a Maxwellian distribution function is found to be always unstable against the growth of very long wavelength oscillations. (Author).
THEORY OF ELECTRON DRIVEN SHOCK WAVES
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Book
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1 edition published in 1960 in English and held by 1 library worldwide Previous calculations of the time required for ion heating in the discharge or driver section of an electrical shock tube yielded values much greater than that in which formation and acceleration of the first luminous front is observed to occur. The model of an electron driven shock presented here shows that the relation between shock velocity, V, and electron temperature, T sub e, which has been established experimentally over a wide range of parameters, remains valid even though the conventional picture of a shock driven by hot ions must be abandoned. Thermal expansion of the hot electron gas accelerates the cold ions, resulting in a shock front or moving electrostatic double layer. Assuming conditions behind the shock to be coupled to those in the discharge region through a simple rarefaction wave, it is found that MV(2)/kT sub e is a universal function of W/MV(2), where W is the effective ionization potential. This is shown to be in excellent agreement with a wide variety of experimental data. (Author).
Linear lumped parameter analysis synchros. vii. simple torque systems
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Book
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1 edition published in 1953 in English and held by 1 library worldwide Formulae are presented for torque gradient and electrical error of a simple torque system, in terms of the basic building blocks - the impedances. A simple torque system consists of a transmitter and a receiver. For this system two torque gradients are defined: one observed at the receiver and one observed at the transmitter. Also a unit torque gradient is defined by the specifications. This is measured on an individual synchro independently of any connections into any system. These may turn out to be unequal. Various plausible physical assumptions are introduced from time to time to simplify results. To be specific there are five assumptions, and among these are two forms of proportionality for the impedances of two synchros of a system - a weak and a strong form. The following comparisons then hold among the various types of torque gradient: (1) the unit torque gradient is equal to either torque gradient of a simple torque system of identical synchros, and (2) to develop the usual formula for either torque gradient of a simple torque system in terms of the individual unit torque gradients we require the strong form of proportionality and no effective mutual resistance. (Author).
Meson nucleon scattering
by R. J Riddell
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Book
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1 edition published in 1953 in English and held by 1 library worldwide
Impact of remote terminal computers on engineering design and development
by B Herzog
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Book
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1 edition published in 1967 in English and held by 1 library worldwide more
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