A parametric beating hypothesis for solar wind acceleration.

This dissertation advances a novel mechanism to explain how particles in the solar wind are heated and, consequently, accelerated. This mechanism involves both kinetic and magnetohydrodynamic (MID) processes. Specifically, the damping of magnetosonic waves, which are produced in the heliosphere, is a kinetic process. The non-linear beating of Alfven waves, which results in the production of the magnetosonic waves, is best described by MHD theory. Until recently, research in the area of heliospheric physics focused upon a putative non-linear process by which Alfven waves cascade from low frequencies to high frequencies and, ultimately, lose their energy to ion-cyclotron damping. The damping is suggested to be responsible for solar wind heating; however, an authoritative model is yet to be produced. The purpose of this thesis is not to refute the former mechanism, which takes place at some level. Rather, it is to determine whether an alternative mechanism competes with the former. The calculation uses the ideal MHD system of equations as a point of departure. These equations are solved, perturbatively, in Fourier space. For the purpose of simplicity, the only terms considered in the solution are those that are of first order in the fluctuating magnetosonic variables and second order in the fluctuating Alfvenic variables. By means of substitutions and rearrangements, the resulting equation can be transformed into an expression for the fluctuating magnetosonic velocity. This expression, combined with the Alfven wave spectrum, can be used to calculate the total energy density of the driven magnetosonic waves. Knowledge of the magnetosonic damping rate, then, yields a characteristic rate of solar wind heating and acceleration, which can be compared to those obtained using other models and observational data. The initial calculation employs a rough approximation to the magnetosonic damping rate to estimate the heating of the solar wind. A refinement of this calculation is accomplished by developing the kinetic theory as a linear response to a ponderomotive force, derived using the two fluid equations. The results of both of these calculations are used in order to investigate the heating and acceleration of the solar wind in regimes of physical interest.Ph.D.Applied SciencesAstronomyNuclear engineeringPlasma physicsPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/123124/2/3068822.pd