The theoretical plasma physics group uses analytical and numerical methods to address a wide spectrum of problems of relevance to space, astrophysical, and laboratory plasmas. Bhattacharjee is involved in fundamental research on magnetic reconnection with applications to magnetospheric substorms, solar coronal heating and flares, and magnetic island dynamics in fusion plasmas. He is also involved in turbulence research, and in particular, the problems of energy and density fluctuation spectra in the magnetized interstellar medium and solar wind, and vorticity intensification and singularity formation in ordinary fluids. Chen is studying magnetic reconnection in simulations and magnetospheric data, particle acceleration at reconnection sites, and electrostatic structures. Kaufmann has created three-dimensional data-based models of the plasma sheet (based on data from the Geotail satellite). The topics that are being studied now using these models involve thermodynamics (changes in the content, entropy, magnetization, several adiabatic invariants, and fast flows) and electric currents (magnetization, guiding center, and parallel currents) in this portion of the Earth's geomagnetic tail. Other topics to be studied involve reconnection, substorms, and energy transport. Raeder's research focuses on the global modeling of Earth's magnetosphere-ionosphere-atmosphere system to study the interaction of the solar wind with Earth's space environment. Besides the basic research aspect, that is, understanding the plasma interaction of planetary magnetospheres, this research has practical applications in the area of space weather effects, that is, harmful effects on technological systems, for example, satellites or power grids.