Fri, 04/06/2018 - 12:30pm to 1:30pm
Morse 401
Space Science Seminar
Gen Li

PhD thesis defense: Interplanetary Transport of Solar Energetic Particles

Abstract:  Solar energetic particles (SEPs) are high-energy ions and electrons originating at or near the Sun. The energies of these particles extend from solar wind energies up to ~10 GeV for ions and ~100 MeV for electrons. This dissertation presents three separate primarily analytical work I (under the supervision of my advisor) have accomplished that illuminates the propagation of SEPs through the solar corona and solar wind. The first work treats the onset phase of a SEP event using the focused transport equation and interpret the origin of the mildly isotropic phase following the anisotropic onset as a natural result of the interplanetary transport of SEPs. In the second work, we analyze the Green’s function of the stationary energetic-particle transport equation and attribute the double-power-law proton differential fluence spectra observed in the largest SEP events as a result of convection and adiabatic cooling in the divergent solar wind. Finally the third work relates the event-integrated wave growth of proton-excited Alfvénic waves in interplanetary space to the proton differential fluence of a SEP event to address the question of how “large” an event should be so that the passage of the streaming protons is enough to noticeably amplify the interplanetary hydromagnetic waves at their cyclotron resonant wavelengths.

Advisor:  Martin Lee