HR: 0800h
AN: NG21A-0204    [Abstracts]
TI: Minimum Dissipative Relaxed States in Astrophysical Plasmas
AU: * Dasgupta, B
EM: dasgupta@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California at Riverside, Riverside, CA 92521, United States
AU: Hu, Q
EM: qiang.hu@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California at Riverside, Riverside, CA 92521, United States
AU: Shaikh, D
EM: dastgeer@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California at Riverside, Riverside, CA 92521, United States
AU: Zank, G P
EM: zank@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California at Riverside, Riverside, CA 92521, United States
AB: We review briefly the problem of relaxation of a magnetized plasma based on the principle of minimum dissipation rate (MDR) of energy. Two situations are considered; one is under the constraint of constant global helicity for a closed system and the other is constant helicity injection rate for an open system. The principle of minimum dissipation rate is closely related to the well-known theorem of irreversible thermodynamics, principle of minimum entropy production rate. Magnetic fields obtained from both the MDR models are essentially non- force free and can support a finite pressure gradient. A self-consistent, time-dependent numerical simulations of dissipative plasmas at a higher Landquist number, typically ~ O(106-107), using full three dimensional compressible MHD code with a numerical resolution of 1283 shows that the global helicity remains approximately constant while magnetic energy is decaying faster and dissipation rate is decaying even faster than the magnetic energy. This justifies the use of of the principle of MDR as an effective minimizer during the process of plasma relaxation. Using a two fluid description, we show that Solar arcade structures can be modeled as a minimum dissipative relaxed state, and different types of arcade structures can be generated. We also present an approach to obtain the flux rope solution and discuss the properties of such flux ropes.
DE: 4430 Complex systems
DE: 4485 Self-organization
DE: 7524 Magnetic fields
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting