Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

188 Biennial Report 2005-075.2.2.6 Two fluid stationary states with external driveA formalism is developed for flowing two fluid stationary states for an externally driven plasmawith dissipation. A coupled equation in flow and field is obtained as the governing equation for thesteady state plasma. In the presence of purely azimuthal flows. this coupled equation resembling amodified Grad-Shafranov equation is solved for the topology relevant to field reversed configuration.The external electric field required to attain the configuration is obtained self-consistently.Ramitendranath Bhattacharyya, Janaki Sita MylavarapuPP5.2.2.7 Effects of finite sized charge on downstream wake patternsA study of wake patterns for extended charged particles introduced into streaming dusty plasmasreveals that for supersonic flows, the potential is lateral in nature while for subsonic flows, themagnitude of transverse wake is greater than lateral wake. The effects of finite size also diminishthe magnitude of the wake potential.Anirban Bose, Janaki Sita MylavarapuPP5.2.2.8 Directional Landau damping of wake-field potentialsThe wake field potentials produced by charged particles moving in a plasma are investigated inthe presence of finite Landau damping effects. In the frame of reference moving with the particle,the phase velocities of the spectrum of waves excited by the moving charge depend on the angle ofpropagation of the wave vector giving rise to a directional wave-particle resonance condition. Asa consequence, the wake structure is seen to decay both along and transverse to the direction ofmotion of the charged particle.Anirban Bose, Janaki Sita MylavarapuPP5.2.2.9 Solar arcades as possible minimum dissipative relaxed statesThe observations of long life time, non uniform pressure variation, and finite plasma flows associatedwith solar arcade type magnetic fields cannot be explained from the conventional ideal MHDanalysis. The principle of minimum dissipation rate of energy is utilized in the framework oftwo fluid model to set up a non-force free relaxation model for understanding the nature of arcadetype solar magnetic fields. The Euler-Lagrange equations are solved using photospheric boundaryconditions. Multiple arcade structures supporting plasma flows have been obtained as solutions.Ramitendranath Bhattacharyya, Janaki Sita Mylavarapu, Brahmananda Dasgupta†, GP Zank† PP