Navigation   about theory   meetings   people   projects   publications   review   home		Jay R. Johnson Office: C-Site T155 Phone: (609) 243-2603 email: jrjohnson@pppl.gov         Dr. J. R. Johnson is a Principal Research Physicist and Head of Space Physics at Princeton Plasma Physics Laboratory. He received his Ph.D. degree from Massachusetts Institute of Technology in 1992. He has published more than 30 papers on theoretical plasma physics. Dr. Johnson's area of expertise is in theoretical plasma physics with emphasis on applications to space plasmas. His past work includes areas of mode conversion associated with the development of a kinetic-fluid model, kinetic Alfven waves and associated plasma transport, linear mode conversion of Alfven ion cyclotron waves in a multi-ion species plasma, global mirror modes, plasma stability analysis, nonlinear plasma waves, and nonlinear dynamics. In particular, he has shown that kinetic Alfven waves could be a significant source for the observed plasma transport across the interface between the solar wind and magnetosphere. He has also shown that Alfven ion cyclotron waves generated in the equatorial region of the magnetosphere could propagate earthward along magnetic field lines and tunnel through the ``stop gaps'' associated with the minority ion species. He has demonstrated a detailed mode conversion analysis that substantial coupling between the propagating modes occurs near the minority ion resonances and that substantial wave power is both transmitted and absorbed. Both the transmitted and absorbed wave power can contribute substantially to energization and outflow of oxygen ions from the ionosphere. He has demonstrated that kinetic Alfven waves at the magnetopause could be a significant source for the observed plasma transport across the interface between the solar wind and magnetosphere. He worked closely with Simon Wing of Johns Hopkins University/Applied Physics Laboratory to interpret remote observations of the plasma sheet to better understand the transport mechanisms. In particular, he has helped to establish constraints on dawn-dusk asymmetries and entropy for quiescent and active-time magnetosphere transport under different solar wind conditions. Recently, he also developed cumulant-based methods for analysis of nonlinear magnetospheric dynamics and detecting high-order statistical dependencies.
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