A study of the two-dimensional incompressible flow of the solar wind past an open terrestrial magnetosphere is presented. The plasma is described by the magnetohydrodynamic (MHD) equations including non-ideal effects such as resistivity and viscosity. The theoretical analysis is based on an ordinary perturbation technique with expansion in orders of large Reynolds and Lundqvist numbers. Magnetic reconnection is assumed to occur at an arbitrary point along a region of the magnetopause, stretching from the sub-solar point to the north. From the analysis we find analytical solutions describing the transition layers north and south of a reconnection point. It is shown that the transition layer north of the reconnection point is thinner than the layer on the south side. It is also shown that in order for steady reconnection to occur, the velocity at the reconnection point must be less than the Alfvén velocity. Using the method of matched asymptotic expansions, we match the transition layer solution with a potential flow solution describing the flow and magnetic field in the exterior magnetosheath.

A one-dimensional model of the interaction between an injected electron beam and an electromagnetic (EM) field inside a coaxial vircator is presented. The effects of the injected electron beam energy spread, anode absorption rate, feedback and injected current premodulation are analyzed. The EM-gains of interaction between the electron beam and TM01, TE11 modes are derived and discussed.

A previous paper, McKenzie and Hagfors (1996 J. Plasma Phys. 55(3), 539–585) henceforth referred to as P1, discussed the excitation of parametric instability in a homogeneous plasma pumped by an external electrostatic field. The discussion was carried out in the fluid approximation, and growth rates and resonance frequencies for several different modes were calculated, some of which had previously been overlooked because of inconsistent cut-off of certain series expansions. In this brief note we show that the fluid treatment gives growth rates and resonance frequencies that agree well with the kinetic treatment.

Using particle-in-cell computer simulation, the processes occurring in a plasma formed by isothermal evaporation of ions and electrons off a planar wall are studied. A simple model to implement three-body recombination is introduced into this scheme; it fulfills momentum and energy conservation and obeys the well-known dependences of the recombination rate on density and temperature. Ion acceleration processes are investigated, during both the particle emission phase and afterwards, during expansion into vacuum. Recombination strongly enhances ion acceleration, since due to the recombination-heated electron subsystem the expansion-front space-charge field is increased. Spatial segregation of the neutral gas cloud and the plasma cloud is demonstrated.

We have developed a new set of transport equations for magnetized, fully ionized gases designed to cover the entire regime from collision-dominated to collisionless flow. The equations are based on a skewed bi-Maxwellian velocity distribution function and describe number density, $n$, flow velocity, ${\vek u}$, parallel and perpendicular temperature, $T_{\parallel}$ and $T_{\perp}$, and heat flow, $\mathbf q$. We choose a velocity distribution function $f(\vek v) = f^{\mathrm{bM}}(1+\phi)$ where $f^{\mathrm{bM}}$ is a bi-Maxwellian and the ‘skewness’, $\phi$, is proportional to $c^3$ instead of the more commonly used $\phi\propto c \ (c \equiv |\vek v-\vek u|)$. We find transport coefficients (heat flux and thermal force) in the collision-dominated limit that are in good agreement with results from classical transport theory. The equations also describe, reasonably well, the flow of collisionless, ionized gases, and should therefore be well suited to describe the transition region–corona–solar wind system and other fully ionized, expanding stellar atmospheres.

Waves launched into a magnetized plasma when it is rapidly compressed were studied in the late 1950s by Adlam and Allen. In this paper we show that the equations describing large amplitude magnetized plasma waves, or Adlam–Allen waves, can be reduced to a single nonlinear equation, namely the Korteweg–de Vries equation and that the solutions of this equation are in agreement with the results obtained previously by Adlam and Allen. The solutions of both the Adlam–Allen equations and the Korteweg–de Vries equation take the form of solitary waves and periodic wave trains.

We have solved the shear flow stability problem of compressible electrically conducting fluid (plasma) in a magnetic field. A comparative analysis is made of the influence of different boundary conditions on shear flow stability. We consider the problems for flows in an unbounded medium and a flow between fixed walls, as well as in the presence of a fixed wall on one side of the shear flow only. Shear flow velocity profiles are treated both in the form of a tangential discontinuity and as being described by a hyperbolic tangent function. For the case of an unbounded flow with a velocity vortex sheet, analytical solutions are found; for all other cases, the solutions are found numerically. Problems are solved for two different positions of the tangential wave vector of oscillations and magnetic field ${\bf k}_t\,{\perp}\, {\bf B}_0$ and ${\bf k}_t\,{\parallel}\, {\bf B}_0$. For shear flows bounded by a fixed wall we found an unstable mode of oscillations produced by the wave, reflected from the wall and transmitted through the shear layer.

If an initially mainly rectilinear electron beam is subject to significant magnetic compression, the conservation of the magnetic moment results in the ultimate formation of a horseshoe distribution in phase space. A similar situation occurs where particles are accelerated into the auroral region of the Earth's magnetic dipole. Such a distribution has been shown to be unstable to a cyclotron resonance maser type of instability and it has been postulated that this may be the mechanism required to explain the production in these regions of auroral kilometric radiation (AKR) and also possibly radiation from other astrophysical objects such as stars with a suitable magnetic field configuration. In this paper we describe a laboratory experiment to investigate the evolution of an electron beam subject to a magnetic compression of up to a factor of 30.

The high-β operating regime of spherical tori (ST), such as in the National Spherical Torus Experiment (NSTX) and the Mega Amp Spherical Tokamak (MAST), makes them attractive fusion devices. For access to such high-β regimes it is necessary to heat and to drive currents in ST plasmas. In the electron cyclotron range of frequencies, such plasmas are overdense to conventional electron cyclotron waves. However, in this frequency range, electron Bernstein waves (EBWs) offer an attractive alternative as they have no density cutoffs. EBWs can be excited in a ST plasma by mode conversion of the extraordinary or the ordinary mode at the upper hybrid resonance. The applications of EBWs in STs range from plasma start-up and heating of the plasma to modifying and controlling its current profile. The controlling of the current profile could provide better confinement as well as help suppress neoclassical tearing modes. The mode conversion to EBWs has been detailed in a variety of papers. This paper deals with two particular topics that further quantify the role of EBWs in spherical tori. The first topic is on the relevance of relativistic effects in describing the propagation and damping of EBWs. The second topic is on plasma current generation by EBWs.

In certain circumstances, small amplitude, weakly nonlinear ion-acoustic waves in a magnetized plasma are governed by a Zakharov–Kuznetsov equation or by a reduced form of the equation. Both equations have a plane solitary travelling-wave solution that propagates at an angle αto the magnetic field. The multiple-scale perturbation method developed by Allen and Rowlands is used to calculate the initial growth rate of a small, transverse, long-wavelength perturbation to these solitary-wave solutions. Previous results in the literature are corrected. A numerical determination of the growth rate is given. For k[mid ] secα[mid ][Lt ]1, where k is the wavenumber of the perturbation, there is excellent agreement between our analytical and numerical results.

A new nonlinear electromagnetic wave mode in a plasma is reported. Its existence depends on the interaction of an intense circularly polarized electromagnetic wave with a plasma, where quantum electrodynamical photon–photon scattering is taken into account. As an illustration, we consider a pair plasma and show that the new mode can be significant in astrophysical settings and in the next generation of laser–plasma systems.

A review of a technique for the application of a new Lambert $W$ function for solving transcendental equations arising in classical problems of plasma and electron beam theories is presented, and the basic mathematical properties of the Lambert $W$ function are outlined. The problems discussed include equilibrium electric charge of a solitary body in plasma, nonlinear ion-acoustic waves, the equilibrium configuration of a neutralized electric beam, the dynamics of shaping virtual cathodes in a medium with viscous friction, and the study of the dispersion equation for electron plasma waves in the framework of generalized Boltzmann kinetics.