His research interests include plasma physics with applications to space and astrophysical plasmas, fusion energy, and high energy density plasmas. Primary among these are magnetic reconnection, a fundamental plasma process which allows the fast conversion of magnetic energy into plasma kinetic energy, including the acceleration of particles to very high energy. It underlies the explosive energy release in solar flares and substorms in the earth's magnetosphere. A second topic is the physics of shocks waves driven by enormous astrophysical explosions, which is the site of the acceleration of cosmic rays, the highest energy particles detected in the cosmos.