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Consider a system consisting of a linear wave equation coupled to a transport equation: \begin{equation*} \Box_{t,x}u =f , \end{equation*} \begin{equation*} (\partial_t + v(\xi) \cdot \nabla_x)f =P(t,x,\xi, D_\xi)g , \end{equation*} Such a system is called \textit{nonresonant} when the maximum speed for particles governed by the transport equation is less than the propagation speed in the wave equation. Velocity averages of solutions to such nonresonant coupled systems are shown to be more regular than those of either the wave or the transport equation alone. This smoothing mechanism is reminiscent of the proof of existence and uniqueness of $C^1$ solutions of the Vlasov-Maxwell system by R. Glassey and W. Strauss for time intervals on which particle momenta remain uniformly bounded, see ``Singularity formation in a collisionless plasma could occur only at high velocities'', \textit{Arch. Rational Mech. Anal.} \textbf{92} (1986), no. 1, 59-90. Applications of our smoothing results to solutions of the Vlasov-Maxwell system are discussed.

In this paper, starting from the bi-fluid Euler-Maxwell system, we derive a complete set of Zakharov-type equations describing laser-plasma interactions. This system involves a quasilinear part which is not hyperbolic and exhibits some elliptic zones. This difficulty is overcome by making a change of unknowns that are strongly related to the dispersive part. This change of variable is a symmetrization of the quasilinear part and is the key of this paper. This shows that the Cauchy problem is locally well-posed.

We prove existence in arbitrary space dimension of nonnegative bounded weak solutions of both the Cauchy problem and an initial-boundary value problem for a degenerate parabolic system which arises in plasma physics.

We consider a one-dimensional, monocharged plasma as described by the Vlasov--Poisson system and investigate the behaviour of the solutions for large times. Using a rescaling method we are able to determine an explicit solution of the system which corresponds to a globally attractive steady state for the rescaled system. We investigate in which sense and at which rate the solutions of the rescaled system converge to this global attractor and interpret the results for the original system.

We establish here a weak stability result for sequences of solutions of the Landau equation. This result relies on the compactness properties recently shown to hold for the equation, and involves a defect measure. It enables us to prove the global existence of a renormalized solution of the ``Landau equation with a defect measure''. We establish an entropy inequality for this solution, and then study its long-time behavior.

We prove that the solution of the Vlasov-Fokker-Planck equation converges to the unique stationary solution with same mass as time tends to infinity. The same result holds in the repulsive coulombic case for the Vlasov-Poisson-Fokker-Planck system; the newtonian attractive case is also studied. We establish positive and negative answers to the question of existence of a stationary solution for the last problem by examining the Poisson-Boltzmann equation.

The validity of the orbital motion limited (OML) theory is reviewed with reference to the floating potential acquired by a spherical object immersed in a plasma. A new and perhaps more realistic approach for obtaining the floating potential is introduced by including the current outward from the spherical object and the current coming from infinity. This novel approach is also valid for cases where the standard OML theory ceases to apply., Comment: 4 pages, 2 figures