Hartmut Ruhl

Magnetic instability by the relativistic laser pulses in overdense plasmas

The magnetic instability driven by the relativistic electron stream generated by ultra-intense laser is investigated with the help of a two-dimensional particle-in-cell simulation, which includes the relativistic binary collision. The linear growth rate of the instability is also studied using the two-stream fluid model, which consists of a fast electron current and a return current. The growth rate is evaluated numerically from the linearized equations of the electron fluids with the Maxwell equations. The kinetic effects of electrons on the magnetic instability are found to reduce the growth rate. The growth rate is maximum at the wavelength near the plasma skin length because of the plasma kinetic effect. When the initial plasma temperature is high, the growth rates of shorter wavelengths are significantly reduced. In the collisional plasma, the growth rates of modes whose wavelength is shorter than the plasma skin length are suppressed and the spectral peak of the growth rate shifts to long wavelength...

Collimated electron jets by intense laser beam-plasma surface interaction under oblique incidence

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Relativistic Vlasov simulation of intense fs laser pulse-matter interaction

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Routes to irreversibility in collective laser–matter interaction

-polarized laser beam on a fully ionized plasma with a low density plasma corona is investigated numerically by particle-in-cell and Vlasov simulations in two dimensions. A single narrow self-focused current jet of energetic electrons is observed to be projected into the corona nearly normal to the target. Magnetic fields enhance the penetration depth of the electrons into the corona. A scaling law for the angle of the ejected electrons with incident laser intensity is given.

COLLECTIVE DYNAMICS AND ENHANCEMENT OF ABSORPTION IN DEFORMED TARGETS

Abstract The results of a relativistic Vlasov simulation of intense laser light-matter interaction are given. Detailed calculations of energy deposition in a short scale length target versus angle of incidence are presented. The degree of absorption is found to depend on the magnitude of a secular surface magnetic field. First order force terms in the electromagnetic fields are identified as the origin of particle jets whose energy exceeds the energy obtained by j × B-heating. The connection between the Brunel effect and anomalous skin effect is given.

Laser absorption and fast electron transport in deformed targets

Collective absorption, so far determined by numerical simulations, is explained in physical terms for cold and warm plasma. After deducing a few general relations for flat targets, interface phase mixing and nonadiabatic electron acceleration in the skin layer are identified as the main physical processes leading to irreversibility, that is, to absorption.