February 1, 2013, 12:00 pm - 1:00 pm

February 1, 12:00 pm - 1:00 pm

Two for One: Observations of 3D Structure in CIRs and Development of the Heavy Ion Sensor

Thomas Broiles, University of Texas at San Antonio

Corotating Interaction Regions (CIRs) are pressure waves created when fast solar wind pushes up against the slow solar wind ahead of it. The shape of CIRs has been thought of as well understood, and discussed in theory and observations since the 1970’s. Here we analyze in detail the orientation of planar magnetic structures in CIRs and compare these observations with predictions of existing models such as the analytical model of Lee [2000] and Enlil. In general, we find our observations to be at odds with model results. In particular, we find that the observed meridional tilts of the planar magnetic structures’ do not agree with expectations. We discuss the implications of our results for models and theories about the origin and evolution of CIR stream structures in the inner heliosphere. We are also involved in the development of the Heavy Ion Sensor (HIS) for Solar Orbiter. We have characterized the response of HIS to solar wind ions using a Monte Carlo simulation. These simulations use a realistic count rate and account for energy losses and angular scattering of the ions as they pass through a carbon foil, the dispersion in the time-of-flight of the secondary electrons, and the pulse height defect within the solid-state detectors. Our results show that HIS is capable of resolving the masses and charge-states of solar wind ions, such as He, C, O, Ne, Mg, and Fe. Results also show that there is some overlap between S and Si, but it is likely that we will be able resolve these ions by integrating these measurements over longer time periods.