bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of relativistic anisotropic plasmas to perpendicular magnetosonic waves
Authors: Landau R. W. , Cuperman S. 
Published: March 2009

The stability of relativistic anisotropic plasmas to the magnetosonic (or righthand compressional Alfvén) wave, near the ion cyclotron frequency, propagating perpendicular to the magnetic field, is investigated. For this case, and for wavelengths larger than the ion Larmor radius and large ion plasma frequency () the dispersion relation is obtained in a simple form and solved. It is shown that for T‖ ╪ T⊥ (even T‖ ≥ T⊥) no instability occurs. This conclusion applies also to the case of the anisotropic interplanetary medium.We note a peculiarity of the dispersion relation. Zero-order and first-order terms cancel so that the relation is of second order in our expansion parameter. The non-relativistic numerical results of Fredricks and Kennel are recovered.
Radiation from a charged particle in a magnetoplasma
Authors: Trulsen J. , fejer J. A. 
Published: March 2009

Two expressions for the power radiated by a charged particle in a homogeneous magnetoplasma are derived, using a method similar to that of Kolomenskii, Eidman and Liemohn. The first expression is identical with that of Eidman. The reason for the correctness of Eidman's result for dispersive media, in spite of his complete neglect of dispersion in the derivation, is explained. Liemohn, by taking dispersion into account at only one stage of the derivation, obtains a result which disagrees with the present one, often by many orders of magnitude, as illustrated by computations.The second expression is derived by several authors by different methods; it is more suitable for computations than the first one. The radiation bands and their limiting frequencies are discussed systematically.
Electron pitch-angle diffusion driven by oblique whistler-mode turbulence
Authors: Lyons L. R. , Thorne R. M. , Kennel C. F. 
Published: March 2009

A general description of cyclotron harmonic resonant pitch-angle scattering is presented. Quasi-linear diffusion coefficients are prescribed in terms of the wave normal distribution of plasma wave energy. Numerical computations are performed for the specific case of relativistic electrons interacting with a band of low frequency whistler-mode turbulence. A parametric treatment of the wave energy distribution permits normalized diffusion coefficients to be presented graphically solely as a function of the electron pitch-angle.The diffusion coefficients generally decrease with increasing cyclotron harmonic number. Higher harmonic diffusion is insignificant at very small electron pitch-angles, but becomes increasingly important as the pitch-angle increases. One thus expected the rate of pitch-angle scattering to decrease with increasing electron energy, since the resonant value of the latter varies proportionately with harmonic number. This indicates that, in mirror-type magnet field geometrics, such as the Earth's radiation belts, the diffusion losses of high energy electrons are likely to be appreciably slower than those at low energy. Integration of the diffusion rates along a complete bounce orbit will be required to clarify this point, however, since the high-energy particles will be subject to more rapid first harmonic diffusion near their mirror points.
Characteristics of the electric field far from and close to a radiating antenna around the lower hybrid resonance in the ionospheric plasma
Authors: Beghin C. , Debrie R. 
Published: March 2009

From a basic discussion of the behaviour of VLF waves propagated almost perpendicularly to the earth 's magnetic field, the lower hybrid resonance (LHR) frequency is seen as a boundary between compressional Alfv én waves and electrostatic sound waves. The disparity of the wavelengths involved leads to a fundamental difference between the characteristics of the AC electric field far from and close to the source.Some detailed observations of this field are presented, from an experiment that used both a mother-daughter technique for large distance measurements and a quadrupole probe technique for the local field, and that was performed in the equatorial ionosphere. The frequency dispersion of quasi-transverse (QT) waves received at a large distance and the amplitude-frequency response of the VLF quadrupole probe are compared with a theoretical analysis for the warm ionospheric plasma. From this analysis, the possibility is established of using the properties of fast and slow waves in active experiments, for measuring simultaneously the LHR, the electron density, a hybrid ion-electron thermal velocity and possibly the plasma drift velocity.
Observation of ‘switch-on’ shocks in a magnetized plasma
Authors: Craig A. D. , Paul J. W. M. 
Published: March 2009

The Charybdis experiment is designed to produce shock waves propagating into a magnetized hydrogen plasma in directions parallel and almost parallel to the initial field and, in particular, the ‘switch-on’ shock. An initial plasmais produced in a pyrex chamber (0.46 m dia., 125 m long) containing an axial magnetic field (Bz up to 0.28 T): a magnetic piston is produced by a fast-rising radial discharge between a short central and an annular outer electrode at one end of the chamber; the Lorentz force on the current sheet causes axial propagation, and under certain conditions a curved shock front propagates ahead of the piston. The Alfvén Mach number of the flow is varied by changing the axial field strength: at high Mach number, where a parallel shock should be gas dynamic, no separated shock is found; at low Mach number, where theory predicts‘switchon’ shock behaviour, a clearly separated curved shock front is found which passes through a point of parallel propagation. Magnetic and electric probe measurements at the point of parallel propagation show the presence of a ‘switchon’ shock. It is suggested that the ‘switch-on’ and adjacent oblique shocks are matched together by an intermediate wave propagating behind the latter and merging with the former.
Transverse ionizing MHD detonation waves. Part 1. Structure, Hugoniot curves and Chapman–Jouguet limit
Authors: Frankenthal Shimshon , Friedland Allan B. , Abarbanel Saul 
Published: March 2009

The structure and jump relations across a one-dimensional ionizing magnetohydrodynamic detonation wave with transverse electromagnetic fields are studied. It is shown that the downstream point in a three-dimensional phase space, constructed from the gas velocity, magnetic field and burned fraction of gas, is of a singular nature and leads to a unique solution. In the zero viscosity, infinite transitional electrical conductivity limit, the ‘fast wave’ degenerates into a pre-compression ionizing shock followed by a perfectly-conducting deflagration zone, and the ‘slow wave’ degenerates into an ordinary gas dynamic pre-compression shock followed by a deflagration zone in which the transition to perfect conductivity occurs. In both cases, a relationship is derived connecting the electric field (which cannot be arbitrarily imposed) and both the upstream variables and parameters describing the ionization transition point. This relationship must be appended to the Rankine–Hugoniot jump relations and a Chapman-Jouguet condition (or its equivalent) to provide a unique relationship between the assumed unknown shock-speed and the downstream state as a function of the assumed known upstream state.The ionization temperature is found to affect the jump and determines the electric field developed upstream. It is found that the Hugoniot consists of two branches: a ‘normal’ one which retains the character of an ordinary detonation Hugoniot, and an ‘anomalous’ one which does not. Although both branches represent detonations endowed with a transition structure, it is suggested that ‘anomalous’ detonations are either unstable or non-evolutionary. The evolution of the topology of the Hugoniot, as a function of the upstream magnetic field and ionizing temperature, is studied and correlated with Chapman-Jouguet propagations. Results are presented for the Chapman-Jouguet jump values and detonation speeds, as functions of dimensionless parameters that represent the upstream magnetic and electric field. Relationships between this upstream electric field and ionization temperature is derived and found to differ according as ionization precedes or follows ignition.
Heating of electrons and ions by inverse bremsstrahlung absorption: a self-similar tate of the plasma
Authors: Balescu R. 
Published: March 2009

It is shown that, under the influence of a monochromatic HF electric field (laser beam), both the electrons and the ions in a high-Z plasma reach a homogeneous and isotropic self-similar state (SSS) in which the distribution functions are of the factorized form: where W±(t) is a scaling velocity, the square of which is proportional to the effective temperature. Whereas the SSS for the electrons was known from previous work, withit is shown here that the corresponding ion SSS exists and is characterized by a simple Maxwellian, øi ø exp (−v2). The discussion of the thermal velocities W±(t), which are obtained in analytical form, provides a transparent physical insight into the heating mechanism of the plasma by inverse bremsstrahlung absorption.
Dynamics of a triple inverse pinch
Authors: Baum P. J. , Bratenahl A. , Cowan M. 
Published: March 2009

Experiments show that plasma may be temporarily confined in a potential well created by three symmetrically spaced inverse pinches. X-type neutral points form at each of the three points of first contact of the inverse pinches and these three neutral points act as flux switches impulsively transferring flux into a central confinement region. The confinement is terminated by a transition to anomalous resistivity at the centre of the device resulting in rapid annihilation of the confining flux by resistive dissipation. The subsequent magnetic field pattern is much more like the vacuum field having only one hyperbolic neutral point.The plasma configuration can probably be made stable for longer periods of time and should also be of interest for studies of interactions between laser light and a plasma in a state of microturbulence.
Statistical mechanics of transport coefficients
Authors: Vasu G. 
Published: March 2009

The problem of transport coefficients in statistical mechanics is reconsidered. A general method is given by which the hydrodynamical equations can straightforwardly obtained starting from the kinetic equation for the one-particle distribution function. From the statistical counterparts of the hydrodynamical equations so derived, the statistical expressions for the transport coefficients are immediately identified.Linearized hydrodynamic modes have recently been the object of very thorough reserach from the viewpoint of irreversible statistical mechanics; in particular, the Brussels school formalism has been used by Résibois to derive the eigenfrequencies of the hydrodynamical modes, whereby operatorial equations for transport coefficients have been obtained (Résibois 1970; see also the instructive book by Balescu (1975) on this subject).
Non-symmetric two-stream instability
Authors: Cuperman S. , Gomberoff L. , Roth I. , Bernstein W. 
Published: March 2009

The recent Plum Brook—NASA experiments on counterstreaming plasma instabilities in which electric field emissions at frequencies [(n + ½) ±α]ωe (n = 1, 2, 3,…, 9, α < 0·5) have been observed, raised the theoretical problem of the non-symmetric two-stream instability. This is the case in which the counterstreaming beams have different velocities in the directions parallel and perpendicular to the static magnetic fields as well as different particle density.We investigate theoretically this problem. The instability of quasi-electrostatic waves at shifted half odd integer multiples of the cyclotron frequency, due to two non-symmetric counterstreaming electron beams, is considered. The beam velocities parallel and perpendicular to the static magnetic field are represented by different double Dirac delta functions; no parameter limitation is imposed. A systematic investigation of (i) the coupling between plasma modes and cyclotron modes and (ii) the coupling between cyclotron modes (beam 1) and cyclotron modes (beam 2) resulting in shifted half odd integer multiples of the cyclotron frequency is carried out.The results include approximate but simple analytical expressions for maximum growth rates and for marginal stability as well as exact numerical solutions for the detailed unstable spectra (1 ≤ m ≤ 20) in both ωτ- and kr-space. The relative weakening or suppression of certain modes is also predicted.
A theoretical investigation of banded chorus
Authors: Nunn David 
Published: March 2009

This paper is a computational study of nonlinear resonant particle trajectories in wave fields consisting of an array of narrow-band waves of closely spaced frequencies and wavenumbers. It looks at two analogous systems, cyclotron resonance with a whistler wavefield and Landau resonance with an electrostatic wave field. It is found that the wave array is able to trap particles in much the same way as a single mode. Inhomogeneity plays a vital role by causing the energy of trapped particles to change.The nonlinear resonant particle current is such as to preserve the modal structure of the wave field, and it does not change the frequency of an individual mode. Power distribution amongst the modes is far from even. Most of the energy goes into the mode at one end of the array, depending on the direction of the inhomogeneity. Also, nonlinear resonant particle excitation of a broad band
signal was found to cause spectral structuring to develop automatically.The theory was applied to one of Coroniti's FTRS analyses of banded chorus elements. The observed spectral behaviour closely accorded with the computational results. The numbers involved fitted the theory very well, and strongly suggested that nonlinear cyclotron resonant particle excitation is the mechanism for banded chorus.
The magnetoplasma dispersion function: some mathematical properties
Authors: Schmitt J. P. M. 
Published: March 2009

The magnetoplasma dispersion function is defined asIt is found in all the dispersion relations for wave propagation perpendicular to the magnetic field in hot plasmas. We review the properties of fω(z), and present several new expansions, which may be of interest in the study of properties of waves in plasmas, or may suggest computational methods for calculating fω(z).
The collisional drift mode in a partly-ionized plasma
Authors: Hudson Mary K. , Kennel Charles F. 
Published: March 2009

The structure of the drift instability is examined in several density regimes. Let λ e be the total electron mean free path, kz the wave-vector component along the magnetic field, and ν ⊥ / ν ∥ the ratio of perpendicular ion diffusion to parallel electron streaming rates. At low densities (kz ν e > 1), the drift mode is isothermal, and should be treated kinetically. In the finite heat conduction regimethe drift instability threshold is reduced at low densities (v⊥/v‖<0·1) and increased at high densities (v⊥/v‖>0·1), as compared with the isothermal threshold. Finally, in the energy transfer limit (kzλe<(m/M)½), the drift instability behaves adiabatically in a fully-ionized plasma, and isothermally in a partly-ionized plasma, for an ion-neutral to Coulomb collision frequency ratio vin/vii>2(m/M)½ at Ti = Tc = Tn.
Reply to the Comments by G. E. Vekstein, D. D. Ryutov and R. Z. Sagdeev
Authors: Balescu R. 
Published: March 2009

I cannot agree with the reasoning of Vekstein, Ryutov & Sagdeev (1982) (VRS), the more so as I see no basic contradiction between their results and mine.The basic equations of the quasi-linear theory are the kinetic equations determining the time evolution of the distribution functions of the electrons and ions, ∂tfe,i and of the spectral densities ∂tψσ(κ) (plus the definition of the diffusion coefficient and the dispersion relations). It is agreed that these equations must be satisfied in any event. The marginal stability is an added approximation (as VRS, of course, admit), and can only be accepted if it is compatible with the basic equations.
Parametric drive of vortex and magnetostatic modes in a strongly non-isothermal plasma
Authors: Rahman H. U. , Shukla P. K. , Murtaza G. 
Published: March 2009

SummaryIn this paper, we have discussed the possibility of excitation of zero-frequency modes by a finite-amplitude electron-sound wave in a highly non-isothermal (Ti ≫ Te) magnetoplasma. According to our investigation, the modulational instabilities of the electron-acoustic waves may produce enhanced twodimensional vortices (convection cells) and magnetic field fluctuation. Both of them can, in turn, modify transport properties of a hot magnetoplasma.Our results could be applicable to plasmas in the earth's magnetotail (Frank, Ackerson & Lepping 1976) or thetapinches, both of which have Ti≫Te. However, for thetapinch application, one should actually modify our results to include plasma non-uniformities. In such a situation, instead of electron-acoustic waves, one encounters ion drift waves (e.g. Shukla, Yu & Varma 1981) whose modulational instabilities can readily be studied following the procedure discussed here.Owing to the lack of experimental data, we cannot at present verify predictions of our theory for plasmas either in space or in a laboratory. However, a typical example shows that the growth rates of both the convection cells and the magnetostatic modes are quite substantial. Hence, the phenomena discussed here may indeed appear in nature.We are grateful to Ming Yu for many useful discussions. The work of one of us(P. K. S.) was performed under the auspices of the Sonderforschungsbereich Plasmaphysik Bochum/J ülich. One of us (H.U.R.) thanks the Deutsche Akademische Austauschdienst for the award of a fellowship.
Side-scattering of an ordinary electromagnetic wave by electron-acoustic oscillations
Authors: Sharma R. P. , Yu M. Y. 
Published: March 2009

The scattering of an ordinary electromagnetic wave into a circularly polarized wave by electron-acoustic oscillations is considered.In this paper, we consider a parametric instability involving electron-acoustic waves which does not have a counterpart in a hot electron plasma, namely the scattering of an ordinary electromagnetic wave into a circularly polarized wave by electron-acoustic waves.
A National Custom: Debating Female Servitude in Late Nineteenth-Century Hong Kong
Authors: CARROLL JOHN M. 
Published: March 2009

AbstractThis article frames the debate about mui-tsai (meizai, female bondservants) in late nineteenth-century Hong Kong within changing conceptions of the colony's political, geographical and cultural position. Whereas some colonial officials saw the mui-tsai system as a national shame that challenged Britain's commitment to ending slavery, others argued that it was an archaic custom that would eventually dissolve as China modernized. The debate also showed the rise of a class of Chinese elites who had accumulated enough power to defend the mui-tsai system as a time-honoured Chinese custom, even while acknowledging that in Hong Kong they lived beyond the boundaries of Chinese sovereignty. Challenging notions of the reach of the colonial state and showing how colonial policies often had unintended consequences, this debate also reveals the analytical and explanatory weakness of concepts such as ‘colonial discourse’ or ‘the colonial mind’.
China in the Japanese Radical Gaze, 1945–1955
Authors: GAYLE CURTIS ANDERSON 
Published: March 2009

AbstractJapanese images of China have much to tell us about the way Japan sees its own modernisation and its place in the international system. Contrary to popular belief, Japan did not turn unabashedly toward the USA after 1945. During the first decade after World War II, a number of important Japanese radical historians and thinkers decided that modernisation could be accomplished without the help of the West. Just when many in Japan were looking to America and Europe as exemplars of modernisation, others looked instead to revolutionary China and its past struggles against Japanese colonialism in the construction of a very different historical position from that ordinarily associated with the early post-war years. Certain Japanese historians, inspired by the push toward decolonisation in Asia, set about writing the history of the present in ways that aligned Japan with modern Chinese history. Even though China had just been liberated from Japanese colonial rule, Japanese Marxists saw their own position—under American imperialism—as historically and politically congruous with China's past war of resistance against Japan (1937–45). Through campaigns to develop a kind of cultural Marxism on the margins of Japanese society, they sought to bring about post-war Japanese ‘national liberation’ from American hegemony in ways that consciously simulated past Chinese resistance to Imperial Japan. Replacing Japan's own cultural Marxist traditions from the pre-war era with the more palpable and acceptable example of China, they also hoped a new form of Asian internationalism could remedy the problem of Japan's wartime past. The historical irony associated with this discursive twist deferred to future generations the problem of how the Left* would come to terms with the past.
Free-energy dissipation constrainst on the accuracy of enzymatic selections
Authors: Blomberg C. , Ehrenberg M. , Kurland C. G. 
Published: March 2009

A bacterium incorporates amino acids into protein with an error frequency close to one in three thousand (Edelman & Gallant, 1977). Nevertheless, the structural differences between related amino acids are so small that it is difficult to see how they can be distinguished from each other with such accuracy (see, for example, Pauling, 1958).Indeed, the selection of amino acids during protein synthesis is carried out twice: first by the aminoacyl-tRNA synthetases and then by the codon-programmed ribosome. Each of these substrate selections is in fact a double selection. In the case of the synthetase both a particular amino acid and a corresponding cognate tRNA must be chosen to form the aminoacyl-tRNA. On the ribosome, the aminoacyl-tRNA must be matched with a cognate codon, and then the mRNA must be advanced by exactly one codon length to position the next codon in the appropriate ribosome site so that it too can be translated.
The physical aspects of energy transduction in biological systems
Authors: Blumenfeld L. A. 
Published: March 2009

The primary energy sources for all the organisms living on the Earth are either sunlight or the energy liberated during chemical transformations (mainly, oxidation) of certain substances – food. Within the cell this energy is transformed, accumulated, and then utilized to ensure a multitude of processes (synthesis of new low- and high-molecular compounds, muscle contraction, luminescence, transfer of ions counter to their concentration gradients, etc.).The role of universal ‘energy keeper’, of the, as it were, ‘energy small change’ in biology is played by the molecules of adenosine tri- phosphate (ATP) whose hydrolytic dissociation in water solutions with the formation of adenosine diphosphate (ADP) and inorganic phosphate (P1) is accompanied by a rather strong decrease of system energy.†