scholarly journals Linearized model collision operators for multiple ion species plasmas and gyrokinetic entropy balance equations

2009 ◽  
Vol 16 (11) ◽  
pp. 112503 ◽  
Author(s):  
H. Sugama ◽  
T.-H. Watanabe ◽  
M. Nunami
Keyword(s):  
Balance Equations ◽  
Entropy Balance ◽  
Model Collision ◽  
Linearized Model ◽  
Ion Species

scholarly journals Improved linearized model collision operator for the highly collisional regime

2019 ◽  
Vol 26 (10) ◽  
pp. 102108 ◽  
Author(s):  
H. Sugama ◽  
S. Matsuoka ◽  
S. Satake ◽  
M. Nunami ◽  
T.-H. Watanabe
Keyword(s):  
Collision Operator ◽  
Model Collision ◽  
Linearized Model ◽  
Collisional Regime

scholarly journals Kinetic theory of electrostatic ion cyclotron waves (QPESIC) in multicomponent plasmas with negative ions

2007 ◽  
Vol 5 (1) ◽  
pp. 45-55 ◽  
Author(s):  
Darko Simic ◽  
Dragan Gajic
Keyword(s):  
Kinetic Theory ◽  
Negative Ions ◽  
Negative Ion ◽  
Bgk Model ◽  
Maxwellian Plasma ◽  
Ion Cyclotron ◽  
Model Collision ◽  
Weakly Ionized ◽  
Component Plasma ◽  
Ion Species

The instabilities of the quasi-perpendicular electrostatic (?B = 0) ioncyclotron waves (QPESIC) are investigated. The kinetic theory with BGK model collision integrals is used to estimate the critical electron drift velocity in the presence of positively or negatively charged resonant ions in multi-component plasma. Analytical evaluation for the ion-cyclotron modes and instabilities in the long-wave range in a weakly-ionized Maxwellian plasma with two positive ion species, one negative ion species and with electrons, drifting along magnetic lines of force is demonstrated. The spectrum in these situations is also given. It is shown that the critical drift decreases as the state of plasma approaches the isothermic state.

Excitation of long-wave quasi-perpendicular electrostatic ion-cyclotron waves in multi-species weakly ionized plasmas

1990 ◽  
Vol 43 (1) ◽  
pp. 23-50 ◽  
Author(s):  
B. S. Milić
Keyword(s):  
Kinetic Equations ◽  
Mean Free Path ◽  
Bgk Model ◽  
Instability Waves ◽  
Background Magnetic Field ◽  
Ion Cyclotron ◽  
Model Collision ◽  
Weakly Ionized ◽  
Electron Mean Free Path ◽  
Ion Species

It is shown, using kinetic equations with BGK model collision integrals, that in a multi-species weakly ionized plasma the quasi-perpendicular ion-cyclotron instability (waves of growing amplitude) excited by the electron drift parallel to the background magnetic field first sets in for long waves (modal wavelengths much larger than the electron mean free path) as the drift is gradually increased, much as in plasmas with only one ion species. Only waves with modal frequencies close to some cyclotron harmonics of some of the ion species present are taken into account in the present work. Owing to the mutual commensurability of all the ion-cyclotron frequencies, more than one species of ions may be ‘resonant’ with any mode of the type considered. The role of ‘resonant’ and ‘non-resonant’ ion species is investigated, both in general and for some particular plasmas. Some numerical details are also given. It is shown that although in most instances the threshold drifts vary monotonically (but not linearly) as the plasma composition is varied, there are cases in which maxima or minima (often depending on the degree of non-isothermality) of the threshold drift magnitude are predicted for some specific plasma compositions. These are usually encountered in plasmas containing ions with different charge numbers.

scholarly journals A Class of Reduced-Order Regenerator Models

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7295
Author(s):  
Raphael Paul ◽  
Karl Heinz Hoffmann
Keyword(s):  
Temperature Distribution ◽  
Balance Equation ◽  
Degrees Of Freedom ◽  
The State ◽  
Balance Equations ◽  
Two Degrees Of Freedom ◽  
Reduced Order ◽  
Entropy Balance ◽  
Numerical Effort ◽  
The Matrix

We present a novel class of reduced-order regenerator models that is based on Endoreversible Thermodynamics. The models rest upon the idea of an internally reversible (perfect) regenerator, even though they are not limited to the reversible description. In these models, the temperatures of the working gas that alternately streams out on the regenerator’s hot and cold sides are defined as functions of the state of the regenerator matrix. The matrix is assumed to feature a linear spatial temperature distribution. Thus, the matrix has only two degrees of freedom that can, for example, be identified with its energy and entropy content. The dynamics of the regenerator is correspondingly expressed in terms of balance equations for energy and entropy. Internal irreversibilities of the regenerator can be accounted for by introducing source terms to the entropy balance equation. Compared to continuum or nodal regenerator models, the number of degrees of freedom and numerical effort are reduced considerably. As will be shown, instead of the obvious choice of variables energy and entropy, if convenient, a different pair of variables can be used to specify the state of the regenerator matrix and formulate the regenerator’s dynamics. In total, we will discuss three variants of this endoreversible regenerator model, which we will refer to as ES, EE, and EEn-regenerator models.

Mathematical modeling and linearized analysis of the jet-pipe hydraulic amplifier applied to a servovalve

2017 ◽  
Vol 233 (2) ◽  
pp. 657-666 ◽  
Author(s):  
Yuesong Li
Keyword(s):  
Flow Characteristic ◽  
Structural Parameters ◽  
Balance Equations ◽  
Absorption Effect ◽  
Characteristic Model ◽  
Flow Balance ◽  
Control Stage ◽  
Improve Model ◽  
Linearized Model ◽  
And Control

The accurate mathematical model of the jet-pipe hydraulic amplifier, which is the pilot control stage of a jet-pipe servovalve, is very necessary to analyze and control the performance of a jet-pipe servovalve. In this paper, based on the hydraulic bridge’s flow balance equations, an improved nonlinear explicit model with the absorption effect is developed. The linearized model and valve coefficients are derived from the nonlinear improve model. To test and verify the improved models, the pressure and flow characteristic model of jet-pipe hydraulic amplifier are verified by the experiment. The results show that the model is approximate to the experimental data. In addition, the influence of structural parameters on performance of jet-pipe hydraulic amplifier is analyzed by simulation.

Effects of Ambipolar Diffusion on Prominence Thread Models

1994 ◽  
Vol 144 ◽  
pp. 315-321 ◽  
Author(s):  
M. G. Rovira ◽  
J. M. Fontenla ◽  
J.-C. Vial ◽  
P. Gouttebroze
Keyword(s):  
Energy Balance ◽  
Transition Region ◽  
Ambipolar Diffusion ◽  
Line Profiles ◽  
Balance Equations ◽  
Model Calculations ◽  
Partial Frequency ◽  
Frequency Redistribution ◽  
Partial Frequency Redistribution ◽  
Theoretical Structure

AbstractWe have improved previous model calculations of the prominence-corona transition region including the effect of the ambipolar diffusion in the statistical equilibrium and energy balance equations. We show its influence on the different parameters that characterize the resulting prominence theoretical structure. We take into account the effect of the partial frequency redistribution (PRD) in the line profiles and total intensities calculations.

Three dimensional deblurring of transmitted-light brightfield micrographs

1993 ◽  
Vol 51 ◽  
pp. 564-565
Author(s):  
Santosh Bhattacharyya
Keyword(s):  
Image Reconstruction ◽  
Three Dimensional ◽  
Transmitted Light ◽  
Reconstruction Algorithms ◽  
3D Image Reconstruction ◽  
Structural Details ◽  
Spread Function ◽  
Early Testing ◽  
Linearized Model ◽  
Image Reconstruction Algorithms

Three dimensional microscopic structures play an important role in the understanding of various biological and physiological phenomena. Structural details of neurons, such as the density, caliber and volumes of dendrites, are important in understanding physiological and pathological functioning of nervous systems. Even so, many of the widely used stains in biology and neurophysiology are absorbing stains, such as horseradish peroxidase (HRP), and yet most of the iterative, constrained 3D optical image reconstruction research has concentrated on fluorescence microscopy. It is clear that iterative, constrained 3D image reconstruction methodologies are needed for transmitted light brightfield (TLB) imaging as well. One of the difficulties in doing so, in the past, has been in determining the point spread function of the system.We have been developing several variations of iterative, constrained image reconstruction algorithms for TLB imaging. Some of our early testing with one of them was reported previously. These algorithms are based on a linearized model of TLB imaging.

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