Effect of Electromagnetic Pulse Transverse Inhomogeneity on the Ion Acceleration by Radiation Pressure

In the ion acceleration by radiation pressure a transverse inhomogeneity of the electromagnetic pulse results in the displacement of the irradiated target in the off-axis direction limiting achievable ion energy. This effect is described analytically within the framework of the thin foil target model and with the particle-in-cell simulations showing that the maximum energy of accelerated ions decreases while the displacement from the axis of the target initial position increases. The results obtained can be applied for optimization of the ion acceleration by the laser radiation pressure with the mass limited targets.

On the collective curvature radiation

The paper deals with the one possible mechanism of the pulsar radio emission, i.e., with the collective curvature radiation of the relativistic particle stream moving along the curved magnetospheric magnetic field lines. It is shown that the electromagnetic wave containing one cylindrical harmonic exp{is{phi}} can not be radiated by the curvature radiation mechanism, that corresponds to radiation of a charged particle moving along curved magnetic field lines. The point is that the particle in vacuum radiates the triplex of harmonics (s, s pm 1), so for the collective curvature radiation the wave polarization is very important and cannot be fixed a priori. For this reason the polarization of real unstable waves must be determined directly from the solution of wave equations for the media. Its electromagnetic properties should be described by the dielectric permittivity tensor ^{epsilon}({omega},k,r), that contains the information on the reaction on all possible types of radiation.

On the mean profiles of radio pulsars I: Theory of the propagation effects

We study the influence of the propagation effects on the mean profiles of radio pulsars using the Kravtsov-Orlov method of the wave propagation in the inhomogeneous media. This approach allows us firstly to include into consideration the transition from geometrical optics to vacuum propagation, the cyclotron absorption, and the wave refraction simultaneously. In addition, arbitrary non-dipole magnetic field configuration, drift motion of plasma particles, and their realistic energy distribution are taken into account. The one-to-one correspondence between the signs of circular polarization and position angle (p.a.) derivative along the profile for both ordinary and extraordinary waves is predicted. Using the numerical integration we now can model the main profiles of radio pulsars. It is shown that standard S-shape form of the p.a. swing can be realized for small enough pair production multiplicity and large enough bulk plasma Lorentz factor only. It is also shown that the value of p.a. maximum derivative, that is often used for determination the angle between magnetic dipole and rotation axis, depends on the plasma parameters and could differ from the rotation vector model (RVM) prediction.

On the radio wave propagation in the pulsar magnetosphere

The key properties of the wave propagation theory in the magntosphere of radio pulsars based on the Kravtsov-Orlov equation are presented. It is shown that for radio pulsars with known circular polarization and the swing of the linear polarization position angle one can determine which mode, ordinary or extraordinary one, forms mainly the mean profile of the radio emission. The comparison of the observational data with the theory predictions demonstrates their good agreement.