The Orientation of the Local Interstellar Magnetic Field

The orientation of the local interstellar magnetic field introduces asymmetries in the heliosphere that affect the location of heliospheric radio emissions and the streaming direction of ions from the termination shock of the solar wind. We combine observations of radio emissions and energetic particle streaming with extensive 3D MHD computer simulations of magnetic field draping over the heliopause to show that the plane of the local interstellar field is ~ 60-90 degrees from the galactic plane. This suggests that the field orientation in the Local Interstellar Cloud differs from that of a larger scale interstellar magnetic field thought to parallel the galactic plane

Argon and Neon Diffusion in Lunar Impact Glass & The Development of the Electron Microprobe Zircon Fission-Track Dating Technique

This dissertation is subdivided into three independent chapters on low temperature thermochronology. In chapter one a new methodology is presented for dating zircon using the fission-track technique. Chapters two and three describe experiments and modeling to determine the diffusion kinetics of Ar and Ne in lunar impact glass

Global Asymmetry of the Heliosphere

Opher et al. 2006 showed that an interstellar magnetic field parallel to the plane defined by the deflection of interstellar hydrogen atoms can produce a north/south asymmetry in the distortion of the solar wind termination shock. This distortion is consistent with Voyager 1 and Voyager 2 observations of the direction of field-aligned streaming of the termination shock particles upstream the shock. The model also indicates that such a distortion will result in a significant north/south asymmetry in the distance to the shock and the thickness of heliosheath. The two Voyager spacecraft should reveal the nature and degree of the asymmetry in the termination shock and heliosheath.Comment: 6 pages, 5 figures, AIP Proceedings of the 5th IGPP "The Physics of the Inner Heliosheath: Voyager Observations, Theory and Future Prospects

Charge exchange avalanche at the cometopause

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95404/1/grl3768.pd

VEGA: En route to Venus and comet Halley

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95520/1/eost5312.pd

Particle acceleration at comets

This paper compares calculated and measured energy spectra of implanted H+ and O+ ions on the assumption that the pick‐up geometry is quasi‐parallel and about 1% of the waves generated by the cometary pickup process propagates backward (towards the comet). The model provides a good description of the implanted O+ and H+ energy distribution near the pickup energies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87298/2/267_1.pd

An analytic solution to the steady‐state double adiabatic equations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94665/1/grl5619.pd

Modeling of nonequilibrium space plasma flows

Godunov-type numerical solution of the 20 moment plasma transport equations. One of the centerpieces of our proposal was the development of a higher order Godunov-type numerical scheme to solve the gyration dominated 20 moment transport equations. In the first step we explored some fundamental analytic properties of the 20 moment transport equations for a low b plasma, including the eigenvectors and eigenvalues of propagating disturbances. The eigenvalues correspond to wave speeds, while the eigenvectors characterize the transported physical quantities. In this paper we also explored the physically meaningful parameter range of the normalized heat flow components. In the second step a new Godunov scheme type numerical method was developed to solve the coupled set of 20 moment transport equations for a quasineutral single-ion plasma. The numerical method and the first results were presented at several national and international meetings and a paper describing the method has been published in the Journal of Computational Physics. To our knowledge this is the first numerical method which is capable of producing stable time-dependent solutions to the full 20 (or 16) moment set of transport equations, including the full heat flow equation. Previous attempts resulted in unstable (oscillating) solutions of the heat flow equations. Our group invested over two man-years into the development and implementation of the new method. The present model solves the 20 moment transport equations for an ion species and thermal electrons in 8 domain extending from a collision dominated to a collisionless region (200 km to 12,000 km). This model has been applied to study O+ acceleration due to Joule heating in the lower ionosphere