Generation of Magnetic Field and Fast Particles During Collision of Electron-Positron Plasma Clouds

We present results of analytical studies and 2D3V PIC simulations of electron-positron plasma cloud collisions. We concentrate on the problem of quasi-static magnetic field generation. It is shown from linear theory, using relativistic two-fluid equations for electron-positron plasmas, that the generation of a quasi-static magnetic field can be associated with the counter-streaming instability. A two-dimensional relativistic particle simulation provides good agreement with the above linear theory and that, in the nonlinear stage of the instability, about 5.3% of the initial plasma flow energy can be converted to magnetic field energy. It is also shown from the simulation that the quasi-static magnetic field undergoes a collision-less change of structure, leading to large scale, long living structures and the production of high-energy particles. These processes may be important for understanding of production of high-energy particles in the region where two pulsar winds collide. This revised version was published online in July 2006 with corrections to the Cover Date.     

Features of Sound Propagation in the Presence of Bubble Clouds in the Perturbed Surface Layer of the Ocean

Doklady Earth Sciences - There are contradictory opinions on the contribution of the near-surface layer of bubbles to the attenuation of low-frequency sound in the ocean. Taking into account the...     

Acoustical Nonlinearity,Sound Absorption,and Scattering in Bubble-Saturated Seawater

A correlation between acoustical nonlinearity, sound absorption, and scattering in a subsurface bubble-saturated layer is established. A model of effective parameters of a bubbly liquid is developed that allows one to obtain results coinciding with experimental field studies. It is shown that “bubbly clouds” under the sea surface increase substantially the sound scattering and the nonlinear acoustic parameter of the seawater.