Physics Department Seminar University of Alaska Fairbanks

J O U R N A L    C L U B

Entropy and Nonadiabatic Heating in The Magnetic Reconnection
Xuanye Ma
Physics Dept. and GI, University of Alaska Fairbanks




Magnetic reconnection is often suggested as an important process in space plasma systems. It can change the topology of the magnetic field, which allows the solar wind plasma to penetrate into the Earth’s magnetosphere. It also converts magnetic energy into the kinetic and thermal energy, which may play a role in solar coronal heating, and reconnection is an important aspect of geomagnetic substorms. A lot of the attention has focused on the plasma and energy transport into the magnetosphere. It is interesting to note, that this plasma entry is associated with dramatic entropy S=p/ρ γ increase, which indicates the existence of strong non-adiabatic heating during the entry process. Observations indicate that the plasma entropy increases by 2 orders of magnitude during the transport from solar wind into the earth magnetosphere. Therefore it is important to examine whether magnetic reconnection can provide sufficient non-adiabatic heating to explain the observed plasma properties and to identify plasma conditions that allow strong nonadiabatic heating. This presentation examines the production of entropy during magnetic reconnection in MHD and Hall MHD simulation, respectively. It is demonstrated that the entropy can indeed strongly increase during magnetic reconnection provided that the plasma beta, i.e., the ratio of thermal to magnetic energy density is is small.


Friday, 27 April 2012

Globe Room, Elvey Building

3:45 PM