HR: 1340h
AN: SH33A-1089    [Abstracts]
TI: Helium at Interplanetary Discontinuities: ACE STEREO Observations and Simulations
AU: Moebius, E
EM: Eberhard.Moebius@unh.edu
AF: University of New Hampshire, 39 College Road, Durham, NH 03824, United States
AU: * Kucharek, H
EM: Harald.Kucharek@unh.edu
AF: University of New Hampshire, 39 College Road, Durham, NH 03824, United States
AU: Allegrini, F
EM: fallegrini@swri.edu
AF: Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, United States
AU: Desai, M
EM: mdesai@swri.edu
AF: Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, United States
AU: Klecker, B
EM: berndt.klecker@mpe.mpg.de
AF: Max-Planck-Institut f. Extraterrestrische Physik, Giessenbach Strasse 1, Garching, 85740, United States
AU: Popecki, M
EM: mark.popecki@unh.edu
AF: University of New Hampshire, 39 College Road, Durham, NH 03824, United States
AU: Farrugia, C
EM: charlie.farrugia@unh.edu
AF: University of New Hampshire, 39 College Road, Durham, NH 03824, United States
AU: Galvin, A
EM: toni.galvin@unh.edu
AF: University of New Hampshire, 39 College Road, Durham, NH 03824, United States
AU: Bochsler, P
EM: peter.bochsler@soho.unibe.ch
AF: Universitaet Bern, Sidlerstrasse 5, Bern, 3012, Switzerland
AU: Karrer, R
EM: reto.karrer@space.unibe.ch
AF: Universitaet Bern, Sidlerstrasse 5, Bern, 3012, Switzerland
AU: Opitz, A
EM: opitz@stereo.unibe.ch
AF: Universitaet Bern, Sidlerstrasse 5, Bern, 3012, Switzerland
AU: Simunac, K
EM: kristin.simunac@unh.edu
AF: University of New Hampshire, 39 College Road, Durham, NH 03824, United States
AB: ACE/SEPICA observations showed that, on average, energetic He+ is after H+ and He2+ the third most abundant energetic particle species in the heliosphere. Depending on the type of the energetic population the He+/He2+ ratio can reach unusually high values in the energy range 250 - 800keV/n ratios up to unity. As a major source of energetic He+ interplanetary pickup ions have been identified that are preferentially accelerated at co-rotating interaction regions (CIRs), transient interaction regions (TIRs), and interplanetary traveling shocks. Most recent data from STEREO/PLASTIC in the energy range of 0.2-80keV/Q show clear evidence of abundant He+ at interplanetary discontinuities. Thus PLASTIC extends the energy range into injection region of the source. Furthermore, ACE/ULEIS and ACE/SEPICA measurements showed that very often 3He2+ and He+ are also accelerated simultaneously at CME-driven IP shocks. This is surprising because, these to species originate from different sources. However, this may indicate that the injection, or the acceleration efficiency of the accelerator for different source population may be similar. From observations, however, this cannot be differentiated easily. In numerical simulations this can be done because there is control over species and distribution functions. In a numerical study we applied test particle simulations and multi-dimensional hybrid simulations to address the contribution of source, injection and acceleration efficiency at shocks to the variability of the helium ratio. These, simulations with and without superimposed turbulence in the shock region will be compared with observations.
DE: 2109 Discontinuities (7811)
DE: 2114 Energetic particles (7514)
DE: 2134 Interplanetary magnetic fields
DE: 2139 Interplanetary shocks
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting