Showing papers in "Physics of fluids. B, Plasma physics in 1989"
TL;DR: In this article, the toroidicity-induced shear Alfven eigenmode was found to be destabilized by fusion alpha particles in an ignited tokamak plasma.
Abstract: The toroidicity‐induced shear Alfven eigenmode is found to be destabilized by fusion alpha particles in an ignited tokamak plasma.
365 citations
TL;DR: In this article, the stability of the ion temperature gradient modes is investigated using the kinetic ion response without expansions in ωD/ω, and a systematic parameter study is carried out using a low-beta circular flux surface equilibrium in order to determine the stability boundaries in ηi vs en space.
Abstract: The stability of the ion temperature gradient modes is investigated using the kinetic ion response without expansions in ωD/ω. A systematic parameter study is carried out using a low‐beta circular flux surface equilibrium in order to determine the stability boundaries in ηi vs en space (ηi=d ln Ti/ d ln n, en=Ln/R). Particular attention is devoted to the consequences of the presence of these modes for anomalous ion transport.
299 citations
TL;DR: In this paper, the physical mechanism responsible for the generation of coherent radiation in the FEL is described and the fundamental role of the ponderomotive wave in bunching and trapping the beam is emphasized.
Abstract: Free‐electron laser (FEL) theory and experiments are reviewed. The physical mechanism responsible for the generation of coherent radiation in the FEL is described and the fundamental role of the ponderomotive wave in bunching and trapping the beam is emphasized. The relationship of the FEL interaction to the beam–plasma interaction is pointed out. Various FEL operating regimes are discussed. These include the high‐gain Compton and Raman regimes, both with and without an axial guiding magnetic field. The linear and nonlinear regimes are examined in detail, with particular emphasis on techniques for achieving efficiency enhancement. The quality of the electron beam used to drive FEL’s is a critical factor in determining their gain and efficiency. The subject of electron beam quality, for different accelerators, is discussed. Key proof‐of‐principle experiments for FELs in an axial guiding magnetic field, as well as those driven by induction linacs, rf linacs, electrostatic accelerators, and storage rings, are reviewed. Finally, the requirements on wigglers and resonators are discussed.
230 citations
TL;DR: In this article, high-resolution numerical studies of decaying two-dimensional magnetohydrodynamic turbulence were performed with up to 10242 collocation points in general periodic systems using various initial states, but restricting consideration to weak velocity-magnetic field correlation ρ.
Abstract: High‐resolution numerical studies of decaying two‐dimensional magnetohydrodynamic turbulence were performed with up to 10242 collocation points in general periodic systems using various initial states, but restricting consideration to weak velocity‐magnetic field correlation ρ. The global evolution is self‐similar with constant kinetic to magnetic energy ratio EV/EM, macro‐ and microscale Reynolds numbers, and correlation ρ, while the total energy decays as E(t)∝(t+t0)−1. As in three dimensions, dissipative small‐scale turbulence adjusts in such a way as to make the energy dissipation rate e independent of the collisional dissipation coefficients. Normalized energy spectra are also invariant. The spectral index in the inertial range is, in general, close to 3/2 in agreement with Kraichnan’s Alfven wave argument Ek =DB1/2e1/2k−3/2, B=(EM)1/2, D≂1.8±0.2, but may be close to 5/3 in transient states, in which turbulence is concentrated in regions of weak magnetic field. In the dissipation range, intermittency...
230 citations
TL;DR: In this paper, a variational principle is developed for the linearized driftkinetic, Fokker-Planck equation, from which both upper and lower bounds for neoclassical transport coefficients can be calculated for plasmas in three-dimensional toroidal confinement geometries.
Abstract: A variational principle is developed for the linearized drift‐kinetic, Fokker–Planck equation, from which both upper and lower bounds for neoclassical transport coefficients can be calculated for plasmas in three‐dimensional toroidal confinement geometries. These bounds converge monotonically with the increasing phase‐space dimensionality of the assumed trial function. This property may be used to identify those portions of phase space that make dominant contributions to the transport process. A computer code based on this principle has been developed that uses Fourier–Legendre expansions for the poloidal, toroidal, and pitch‐angle dependences of the distribution function. Numerical calculations of transport coefficients for a plasma in the TJ‐II flexible heliac [Nucl. Fusion 28, 157 (1988)] are used to demonstrate the application of this procedure.
193 citations
TL;DR: In this article, a calculation is presented that accounts for rapid nonlinear growth of the m = 1 kink-tearing instability, which justifies the use of the helicity conservation assumption.
Abstract: A calculation is presented that accounts for rapid nonlinear growth of the m=1 kink‐tearing instability. The equilibrium analysis contained in the Rutherford theory [Phys. Fluids 16, 1903 (1973)] of nonlinear tearing‐mode growth is generalized to islands for which the constant‐ψ approximation is not valid. Applying the helicity‐conservation assumption introduced by Kadomtsev [Plasma Physics and Controlled Nuclear Fusion Research (IAEA, Vienna, 1977), Vol. I, p. 555], the presence of a current‐sheet singularity is shown that gives rise to a narrow tearing layer and rapid reconnection. This rapid reconnection, in turn, justifies the use of the helicity conservation assumption. The existence of a family of self‐similar m=1 equilibrium islands is demonstrated. The formalism introduced here is shown to apply both to the case of the m=1 kink‐tearing mode and to the case of forced reconnection. These two cases are compared and contrasted.
170 citations
TL;DR: In this paper, a unified theory of ion pressure gradient driven drift wave instabilities and transport is presented, which ties the longwavelength trapped ion mode to the moderate-wavelength hydrodynamic mode in toroidal geometry.
Abstract: A unified theory of ion‐pressure‐gradient‐driven drift wave instabilities and transport is presented, which ties the long‐wavelength trapped‐ion mode to the moderate‐wavelength hydrodynamic mode in toroidal geometry. An analytic dispersion relation that retains ion drift resonances, and keeps the leading‐order contribution from finite Larmor radius effects and parallel compressibility, is derived. Results indicate that the slab and toroidal branches of these instabilities are of comparable importance, and are both strong candidates to explain the observed anomalous ion loss in toroidal fusion devices. However, it is concluded that in the limit of flat‐density profiles characteristic of H‐mode discharges, the stabilizing influence of perpendicular compressibility is insufficient to corroborate an improvement, if any, in ion confinement quality. Mixing‐length expressions for the fluctuation amplitudes and both electron and ion transport coefficients are derived. Results also indicate that the heretofore experimentally observed favorable current scaling of the energy confinement time may saturate in low ion‐collisionality discharges. Finally, it is shown that a population of energetic trapped particles, such as those that may be produced during radio frequency or perpendicular neutral beam heating, can significantly exacerbate the instability. Several suggestions for experiments are made to help in differentiating among various anomalous transport scenarios.
161 citations
TL;DR: In this paper, the nonlinear coupling coefficient and energy transfer associated with three-wave interactions were computed from measured data of the turbulent edge plasma of the Texas Experimental Tokamak.
Abstract: The nonlinear coupling coefficient and the energy transfer associated with three‐wave interactions are computed from measured data of the turbulent edge plasma of the Texas Experimental Tokamak(TEXT) [Nucl. Technol. Fusion 1, 479 (1981)]. The results show the presence of three‐wave interactions. The interactions cause energy to cascade away from the dominant waves of the spectrum primarily toward lower, but also toward higher frequencies. The results are obtained with a new digital spectral analysis technique based on the estimation of higher‐order cumulants. The method is discussed and tested on a simulation experiment. The same technique is useful for neutral fluids as well.
160 citations
TL;DR: In this paper, a phenomenological treatment of the inertial range of isotropic statistically steady magnetohydrodynamic turbulence is presented, extending the theory of Kraichnan [Phys. Fluids 8, 1385 (1965)].
Abstract: A phenomenological treatment of the inertial range of isotropic statistically steady magnetohydrodynamic turbulence is presented, extending the theory of Kraichnan [Phys. Fluids 8, 1385 (1965)]. The role of Alfven wave propagation is treated on equal footing with nonlinear convection, leading to a simple generalization of the relations between the times characteristic of wave propagation, convection, energy transfer, and decay of triple correlations. The theory leads to a closed‐form steady inertial range spectral law that reduces to the Kraichnan and Kolmogorov laws in appropriate limits. The Kraichnan constant is found to be related in a simple way to the Kolmogorov constant; for typical values of the latter constant, the former has values in the range 1.22–1.87. Estimates of the time scale associated with spectral transfer of energy also emerge from the new approach, generalizing previously presented ‘‘golden rules’’ for relating the spectral transfer time scale to the Alfven and eddy‐turnover time scales.
138 citations
TL;DR: In this article, a new derivation of the ion temperature gradient threshold for weak density grandient ηi modes when ion transit resonances are taken into account, along with the properties of these negative instabilities when the thresholds are exceeded.
Abstract: Experimental results from tokamaks such as DIII‐D [Phys. Fluids 31, 3738 (1988)] and JET [Proceedings of the 15th European Conference on Controlled Fusion and Plasma Heating (European Physical Society, Budapest, 1988), Vol. 12B, Part 1, p. 2239] have indicated that the electron density profile in H‐mode (‘‘high confinement’’) discharges can be nearly flat over most of the plasma and in some cases, even inverted (outwardly peaked). These conditions have very interesting implications for pictures of anomalous thermal transport, based on the presence of ion temperature gradient (ηi ) drift instabilities. The present paper includes (i) a new derivation of the ion temperature gradient threshold for weak density grandient ηi modes when ion transit resonances are taken into account; and (ii) the first derivation of threshold conditions for the onset of ηi modes when ηi is negative, along with the properties of these negative ηi instabilities when the thresholds are exceeded. Possible consequences for confinement in H‐mode plasmas are discussed.
121 citations
TL;DR: In this article, the results of fully compressible, Fourier collocation, numerical simulations of the Orszag-Tang vortex system are presented, and it is found that compressible effects develop within one or two Alfven transit times, as manifested in the spectra of compressible quantities such as the mass density and the nonsolenoidal flow field.
Abstract: In this paper the results of fully compressible, Fourier collocation, numerical simulations of the Orszag–Tang vortex system are presented. The initial conditions for this system consist of a nonrandom, periodic field in which the magnetic and velocity field contain X points but differ in modal structure along one spatial direction. The velocity field is initially solenoidal, with the total initial pressure field consisting of the superposition of the appropriate incompressible pressure distribution upon a flat pressure field corresponding to the initial, average Mach number of the flow. In these numerical simulations, this initial Mach number is varied from 0.2–0.6. These values correspond to average plasma beta values ranging from 30.0 to 3.3, respectively. It is found that compressible effects develop within one or two Alfven transit times, as manifested in the spectra of compressible quantities such as the mass density and the nonsolenoidal flow field. These effects include (1) a retardation of growth of correlation between the magnetic field and the velocity field, (2) the emergence of compressible small‐scale structure such as massive jets, and (3) bifurcation of eddies in the compressible flow field. Differences between the incompressible and compressible results tend to increase with increasing initial average Mach number.
TL;DR: In this article, direct numerical simulations of decaying two-dimensional magnetohydrodynamic flows at Reynolds numbers of several thousand were performed, using resolutions of 10242 collocation points, with an inertial range extending to about one decade, with spectral properties depending on the velocity-magnetic field correlation.
Abstract: Direct numerical simulations of decaying two‐dimensional magnetohydrodynamic flows at Reynolds numbers of several thousand are performed, using resolutions of 10242 collocation points. An inertial range extending to about one decade is observed, with spectral properties depending on the velocity–magnetic field correlation. At very small scales, resistive tearing destabilizes current sheets generated by the inertial dynamics and leads to the formation of small‐scale magnetic islands, which may then grow and reach the size of inertial scales.
TL;DR: In this article, the radial sheath, which occurs whenever confining magnetic field lines lie in the plasma boundary surface, is examined, with special reference to the radial vicinity of a tokamak limiter.
Abstract: The boundary layer arising in the radial vicinity of a tokamak limiter is examined, with special reference to the TEXT tokamak [Nucl. Fusion 27, 1125 (1987); Phys. Fluids 27, 2956 (1984)]. It is shown that sheath structure depends upon the self‐consistent effects of ion guiding‐center orbit modification as well as the radial variation of E×B‐induced toroidal rotation. Reasonable agreement with experiment is obtained from an idealized model, which, however simplified, preserves such self‐consistent effects. It is argued that the radial sheath, which occurs whenever confining magnetic field lines lie in the plasma boundary surface, is an object of some intrinsic interest. It differs from the more familiar axial sheath because magnetized charges respond very differently to parallel and perpendicular electric fields.
TL;DR: In this paper, a simple variational principle giving an estimate for the resulting growth rate and the threshold for stability is derived in terms of quantities relating to the ideal system with and without a perfectly conducting wall.
Abstract: External magnetohydrodynamic modes stabilized by the presence of a close‐fitting perfectly conducting wall become destabilized when the wall is assumed to possess finite resistivity. A simple variational principle giving an estimate for the resulting growth rate and the threshold for stability is derived in terms of quantities relating to the ideal system with and without a perfectly conducting wall. This variational principle is valid for an arbitrary three‐dimensional external mode in an arbitrarily shaped plasma possessing an arbitrarily shaped, but thin, resistive wall. As an example of the utility of the method, the variational principle is used to investigate the axisymmetric (n=0) stability of straight, zero pressure elliptical tokamaks with arbitrary current density profiles in the presence of a resistive wall.
TL;DR: In this paper, the collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics, which is used to calculate the electrical conductivity of a uniform electron-ion plasma with infinitely massive ions.
Abstract: The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. In this formulation the collision operator is expressed in terms of five scalar potentials that are given by one‐dimensional integrals over the distribution function. This formulation is used to calculate the electrical conductivity of a uniform electron–ion plasma with infinitely massive ions.
TL;DR: Bell et al. as discussed by the authors used a rapidly gated, intensified TV camera to study the visible light emission from the inner wall region of the TFTR tokamak and observed strong filamentation of the neutral deuterium Dα light when the camera gating time is <100 μsec during neutral beam-heated discharges.
Abstract: Images of the visible light emission from the inner wall region of the TFTR tokamak [M. G. Bell et al., in Plasma Physics and Controlled Nuclear Fusion Research 1988, Proceedings of the 12th International Conference, Nice, France (IAEA, Vienna, in press)] have been made using a rapidly gated, intensified TV camera. Strong ‘‘filamentation’’ of the neutral deuterium Dα light is observed when the camera gating time is <100 μsec during neutral‐beam‐heated discharges. These turbulent filaments vary in position randomly versus time and have a poloidal wavelength of ≊3–5 cm, which is much shorter than their parallel wavelength of ≊100 cm. A second and new type of edge fluctuation phenomenon, which is called a ‘‘merfe,’’ is also described. Merfes are a regular poloidal pattern of toroidally symmetric, small‐scale marfes that move away from the inner midplane during the current decay after neutral beam injection. Some tentative interpretations of these two phenomena are presented.
TL;DR: In this paper, the asymptotic theory of Choudhary and Felsen on the propagation of scalar inhomogeneous waves in two-dimensional isotropic media is extended to the case of three-dimensional vector fields.
Abstract: The asymptotic theory of Choudhary and Felsen [IEEE Trans. Antennas Propag. AP‐21, 827 (1973)] on the propagation of scalar inhomogeneous waves in two‐dimensional isotropic media is extended to the case of three‐dimensional vector fields. The theory is applied to the propagation of Gaussian beams in nonhomogeneous media. The wave trajectory equations are then reformulated for anisotropic media and used for tracking a Gaussian beam in a tokamak plasma.
TL;DR: In this article, four models of collisionless one-dimensional plasma flow to a boundary are compared with regard to their predictions of particle and heat fluxes to the boundary for a given plasma density and temperature far from the boundary.
Abstract: Four models of collisionless one‐dimensional plasma flow to a boundary are compared with regard to their predictions of particle and heat fluxes to the boundary for a given plasma density and temperature far from the boundary. The models include two kinetic treatments, that of Emmert et al. [Phys. Fluids 23, 803 (1980)], and that of Bissell and Johnson [Phys. Fluids 30, 779 (1987)], an isothermal fluid model, Self and Ewald [Phys. Fluids 9, 2486 (1966) and Stangeby, [Phys. Fluids 27, 2699 (1984)], and an adiabatic fluid model, Zawaideh, Najmabadi, and Conn [Phys. Fluids 29, 463 (1986)]. The fluid models do not explicitly include collisions; however, the adiabatic closure condition employed, namely, neglect of ion heat conduction, implies a degree of ion self‐collisionality. It is found that the particle and heat fluxes to the boundary differ very little among the four models—spanning a range of about ±10%. It is therefore concluded that, with regard to modeling of such important practical quantities as ou...
TL;DR: In this article, two EIC wave modes, the K+ and SF−6 modes, were investigated in plasmas containing K+ positive ions, electrons, and negative ions.
Abstract: Electrostatic ion‐cyclotron (EIC) waves have been investigated in plasmas containing K+ positive ions, electrons, and SF−6 negative ions Two EIC wave modes are generally present, the K+ and SF−6 modes Their frequencies increase with increasing e, the percentage of negative ions, while the critical electron drift velocities for excitation of either mode decrease with increasing e The observations are discussed on the basis of available theories
TL;DR: In this paper, the second-order perturbed distribution function produced by a nonlinear Alfven wave was obtained for the plasma density perturbation associated with an envelope-modulated wave.
Abstract: The Vlasov theory is used to study kinetic corrections to fluid descriptions of Alfven wave nonlinearity. The method is to obtain an expression for the second‐order perturbed distribution function produced by a nonlinear Alfven wave. From this distribution function a kinetically correct expression is obtained for δn, the plasma density perturbation associated with an envelope‐modulated Alfven wave. This kinetic theory result differs substantially from the fluid expression when the plasma β≳1, and the electron and ion temperatures are approximately equal. This result is of interest because density fluctuations are an observationally accessible indicator of wave nonlinearity in solar system Alfven waves. It also will assist in the determination of properties of Alfven waves in the interstellar medium. Finally, this analysis also yields a kinetically correct expression for u, the magnetic field‐aligned component of the plasma fluid velocity. For parallel‐propagating wave packets, this field‐aligned flow is a major or even predominant contributor to the wave nonlinearity. Therefore these results provide a starting point for a general discussion of kinetic effects on Alfven wave nonlinearity.
TL;DR: In this paper, an approximate normal mode analysis of plasma current diffusion in tokamaks is presented, based on numerical solutions of the current diffusion equation in cylindrical geometry.
Abstract: An approximate normal mode analysis of plasma current diffusion in tokamaks is presented. The work is based on numerical solutions of the current diffusion equation in cylindrical geometry. Eigenvalues and eigenfunctions are shown for a broad range of plasma conductivity profile shapes. Three classes of solutions are considered that correspond to three types of tokamak operation. Convenient approximations to the three lowest eigenvalues in each class are presented, and simple formulas for the current relaxation time scales are given and applied to several cases of simple current relaxation as well as noninductive current drive. Simulations of current relaxation with and without current redistribution caused by a ‘‘sawtooth’’ model show that sawteeth can considerably shorten the relaxation time if the sawtooth region extends to r∼a/2.
TL;DR: In this article, an incompressible fluid model of the Rayleigh-Taylor instability is generalized to include self-consistent diffuse boundaries, which can predict the scaling of the instability cutoff over an extended parameter range and its dependence on the heat conduction law.
Abstract: An incompressible fluid model of the ablative Rayleigh–Taylor instability [Phys. Fluids 29, 2067 (1986)] is generalized to include self‐consistent diffuse boundaries. With diffuse boundaries the incompressible model is found to be in excellent agreement with a number of previous stability studies of laser ablation. The present theory can predict the scaling of the instability cutoff over an extended parameter range and its dependence on the heat conduction law. It is found that more favorable stability behavior can be obtained both for weak and strong thermal diffusion. Furthermore a strong dependence of the stabilization mechanism on the functional form of the heat conductivity is indicated. Representative conditions for laser ablation are identified and discussed in detail.
TL;DR: In this paper, the relativistic modulational instability of two laser beams in a beat-wave accelerator is investigated, and it is shown that this instability can seriously distort the incident laser pulse shapes on the particle-acceleration time scale.
Abstract: The collinear propagation of an arbitrary number of finite‐amplitude waves is modeled by a system of coupled nonlinear Schrodinger equations; one equation for each complex wave amplitude. In general, the waves are modulationally unstable with a maximal growth rate larger than the modulational growth rate of any wave alone. Moreover, waves that are modulationally stable by themselves can be driven unstable by the nonlinear coupling. The general theory is then applied to the relativistic modulational instability of two laser beams in a beat‐wave accelerator. For parameters typical of a proposed beat‐wave accelerator, this instability can seriously distort the incident laser pulse shapes on the particle‐acceleration time scale, with detrimental consequences for particle acceleration.
TL;DR: In this article, the authors investigated the m = 1 kink mode in the high temperature regime where the width of the singular layer is determined by the mean ion gyroradius. And they derived a dispersion relation that contains the full kinetic response of the ions.
Abstract: The m=1 kink mode is investigated in the high temperature regime where the width of the singular layer is determined by the mean ion gyroradius. This regime is reached in a number of present‐day fusion experiments with strong auxiliary heating. A dispersion relation that contains the full kinetic response of the ions is derived and analyzed. The growth rates are larger than the corresponding ones obtained from fluid theory. Diamagnetic stabilization is weaker than in the fluid case. Ion temperature gradients are shown to be stabilizing at low values of the diamagnetic frequency and destabilizing at large values.
TL;DR: In this article, a theory of applied-B ion diodes is developed and presented in detail, which incorporates the self-consistent virtual cathode motion to obtain the steadystate ion current as a function of diode voltage.
Abstract: A recently introduced theory of applied‐B ion diodes [Phys Rev Lett 59, 2295 (1987)] is developed and presented in detail The theory incorporates the self‐consistent virtual cathode motion to obtain the steady‐state ion current as a function of diode voltage The existence of a limiting voltage at which the ion current diverges is demonstrated The voltage–current characteristics of the diode are combined with a simple circuit model of the accelerator to calculate the operating point of the diode The theoretical results are in good agreement with experimental data at peak power An important consequence of the theory is a relation between the limiting diode voltage and the insulating magnetic flux, suggesting a late‐time voltage decay driven by flux penetration into the anode plasma
TL;DR: In this article, the nonlinear evolution of the magnetohydrodynamic (MHD) parametric instability of wave fluctuations propagating along an unperturbed magnetic field is investigated.
Abstract: The nonlinear evolution of the magnetohydrodynamic (MHD) parametric instability of wave fluctuations propagating along an unperturbed magnetic field is investigated. Both a magnetohydrodynamic perturbation‐theoretical approach and a nonlinear MHD simulation are used. It is shown that high harmonic waves are rapidly excited by wave–wave coupling, and that the wave spectrum evolves from a state containing a small number of degrees of freedom in k space to one which contains a large number of degrees of freedom. It is found that the spectral evolution prior to nonlinear saturation is well described by the perturbation theory. During this stage, the ratio of the growth rate of the nth harmonic wave to the linear growth rate of the fundamental wave is n. The nonlinear saturation stage is characterized by a frequency shift of the fundamental wave that destroys the wave–wave resonance condition which, in turn, causes the wave amplitude to cease its growth.
TL;DR: In this article, a fast scanning versatile probe combination has been developed, which operates simultaneously as a magnetized probe, an unmagnetized probe and an emissive probe, with characteristic probe size greater than and smaller than ion gyroradius, respectively.
Abstract: Plasma flow measurements in the presheath have been performed using two types of directional electric ‘‘Mach’’ probes, in the PISCES facility at UCLA [J. Nucl. Mater. 121, 277 (1984)]. A fast scanning versatile probe combination has been developed, which operates simultaneously as a ‘‘magnetized’’ Mach probe, an ‘‘unmagnetized’’ Mach probe (with characteristic probe size greater than and smaller than ion gyroradius, respectively), and an emissive probe. Presheaths have been investigated by inserting a small object at the center of the plasma column. Variations in plasma flow velocity, density, and potential along the presheath have been deduced by fluid and kinetic theories. A comparison is made between Mach numbers obtained from the magnetized probe and the unmagnetized probe. Incorporation of shear viscosity of order ∼0.5nmiD⊥ in the cross‐field transport along the presheath seems best to model the results. The cross‐field diffusivity (D⊥) is found to scale approximately proportional to B−1/2, with magn...
TL;DR: Theoretical and computer simulations are used to describe the inelastic vortex-vortex and vortex-wave interactions that lead to the quasicoherent transport of plasma across a constant magnetic field in 2D systems as discussed by the authors.
Abstract: Theory and computer simulations are used to describe the inelastic vortex–vortex and vortex–wave interactions that lead to the quasicoherent transport of plasma across a constant magnetic field in 2‐D systems. Monopole and dipole drift wave vortices with radii r0 large compared with the ion inertial scale length ρs are shown to produce transport at the rate un ∫ dσ(b)≤nvvder0, where nv is the vortex line density and dσ(b) is the inelastic collision cross section for the impact parameter b. The transport during collisions and mergings is evaluated from the evolution of a passively convected scalar concentration of test particles.
TL;DR: In this paper, the analysis of the hydromagnetic Alfven wave and fire-hose instability in the nonrelativistic regime was extended to the fully relativistic (FRS) regime, and it was shown that the FRS effect has a non-negligible effect on the wave and stability properties of the low frequency modes under certain conditions.
Abstract: Detailed properties of the classical hydromagnetic Alfven wave and the fire‐hose instability, driven by an excess in the parallel energy, are well understood in the nonrelativistic regime. In this Brief Communication, the analysis is extended to the fully relativistic regime. The analysis is carried out for fully relativistic bi‐Maxwellian distributions of electrons and ions (or positrons). It is shown that the relativistic effect has a non‐negligible effect on the wave and stability properties of the low‐frequency modes under certain conditions.
TL;DR: In this article, the scaling of the wave properties with the ratio of the ion gyroradius to the magnetic confinement radius is discussed and the nonlinear evolution of the instability is investigated more thoroughly.
Abstract: Structuring that results from plasma streaming at sub‐Alfvenic speeds across an external magnetic field is considered. Previously, it has been proposed the lower hybrid drift instability enhanced by the deceleration of the plasma by the field produces the flute modes observed on the surface of expanding laser produced plasmas and the AMPTE magnetotail releases [Eos (Trans) 63, 843 (1982)]. An appropriate dispersion equation to describe the properties of the unstable waves has been derived and particle simulations carried out to show the growth and evolution of the instability. The salient features of this earlier work are reviewed here, and then additions and refinements to the theory and simulations are described. In particular, the scaling of the wave properties with the ratio of the ion gyroradius to the magnetic confinement radius is discussed and the nonlinear evolution of the instability is investigated more thoroughly. The consequences of these results, both for the laser experiments and for AMPTE,...