James Raines

On the fast coronal mass ejections in October/November 2003: ACE‐SWICS results

[1]xa0Coronal Mass Ejections (CMEs) originate deep in the corona and, due to physical processes that are currently not well understood, are often accelerated to speeds well above the average solar wind speed. Solar wind compositional measurements provide important information about the source of such ejections, the heating profiles, and their expansion in the inner heliosphere. In this article we present data from the Solar Wind Ion Composition Spectrometer (SWICS), part of the Advanced Composition Explorer (ACE) spacecraft, describing the kinetic and compositional properties of the solar wind associated with CMEs that occurred in late October and early November 2003. In particular, we discuss the ionic composition of C, O, and Fe, as well as the relative elemental composition of C, O, and Fe, present in those CMEs.

Interpreting ~1 Hz magnetic compressional waves in Mercury's inner magnetosphere in terms of propagating ion-Bernstein waves

We show that ~1u2009Hz magnetic compressional waves observed in Mercurys inner magnetosphere could be interpreted as ion-Bernstein waves in a moderate proton beta ~0.1 plasma. An observation of a proton distribution with a large planetary loss cone is presented, and we show that this type of distribution is highly unstable to the generation of ion-Bernstein waves with low magnetic compression. Ray tracing shows that as these waves propagate back and forth about the magnetic equator; they cycle between a state of low and high magnetic compression. The group velocity decreases during the high-compression state leading to a pileup of compressional wave energy, which could explain the observed dominance of the highly compressional waves. This bimodal nature is due to the complexity of the index of refraction surface in a warm plasma whose upper branch has high growth rate with low compression, and its lower branch has low growth/damping rate with strong compression. Two different cycles are found: one where the compression maximum occurs at the magnetic equator and one where the compression maximum straddles the magnetic equator. The later cycle could explain observations where the maximum in compression straddles the equator. Ray tracing shows that this mode is confined within ±12° magnetic latitude which can account for the bulk of the observations. We show that the Doppler shift can account for the difference between the observed and model wave frequency, if the wave vector direction is in opposition to the plasma flow direction. We note that the Wentzel-Kramers-Brillouin approximation breaks down during the pileup of compressional energy and that a study involving full wave solutions is required.

Heating of Heavy Ions by Interplanetary Coronal Mass Ejection Driven Collisionless Shocks

Shock heating and particle acceleration processes are some of the most fundamental physical phenomena of plasma physics, with countless applications in laboratory physics, space physics, and astrophysics. This study is motivated by previous observations of nonthermal heating of heavy ions in astrophysical shocks. Here we focus on shocks driven by interplanetary coronal mass ejections (ICMEs), which heat the solar wind and accelerate particles. This study focuses specifically on the heating of heavy ions caused by these shocks. Previous studies have focused only on the two dynamically dominant species, H+ and He+2. This study utilizes thermal properties measured by the Solar Wind Ion Composition Spectrometer (SWICS) aboard the Advanced Composition Explorer (ACE) spacecraft to examine heavy ion heating. This instrument provides data for many heavy ions not previously available for detailed study, such as oxygen (O+6, O+7), carbon (C+5, C+6), and iron (Fe+10). The ion heating is found to depend critically on the upstream plasma β, mass-to-charge ratio of the ion, M/Q, and shock magnetic angle, θBn. Ours is similar to past studies in that there is no strong dependence of ion heating on Mach number. The heating mechanism described in Lee & Wu is examined to explain the observed heating trends in the heavy ion thermal data.