The role of entropy in magnetotail dynamics

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Journal of Geophysical Research

OSTI ID:956636

Birn, Joachim ^[1]; Zaharia, Sorin ^[1]; Hesse, Michael ^[2]; Schindler, K ^[3]

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1. Los Alamos National Laboratory
2. NASA/GSFC
3. INSTITUT FOR THEORETISCHE

The role of entropy conservation and loss in magnetospheric dynamics, particularly in relation to substorm phases, is discussed on the basis of MHD theory and simulations, using comparisons with PIC simulations for validation. Entropy conservation appears to be a crucial element leading to the formation of thin embedded current sheets in the late substorm growth phase and the potential loss of equilibrium. Entropy loss (in the form of plasmoids) is essential in the earthward transport of flux tubes (bubbles, bursty bulk flows). Entropy loss also changes the tail stability properties and may render ballooning modes unstable and thus contribute to cross-tail variability. We illustrate these effects through results from theory and simulations. Entropy conservation also governs the accessibility of final states of evolution and the amount of energy that may be released.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: DOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 956636
• Report Number(s): LA-UR-08-07873; LA-UR-08-7873
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Vol. 114; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
97 MATHEMATICS AND COMPUTING
BUBBLES
CURRENTS
DYNAMICS
ENERGY
ENTROPY
EQUILIBRIUM
GROWTH
MAGNETOTAIL
PLASMOIDS
POTENTIALS
STABILITY
TRANSPORT
TUBES
VALIDATION