The ionic charge composition of energetic particles as observed in planetary environments and in interplanetary space provides crucial information on their source, is an important parameter for the diagnostic of the plasma conditions at the source region and provides fundamental information about the acceleration and propagation processes in planetary magnetospheres, at the Sun and in interplanetary space. In Earthâ€™s magnetosphere, for example, the measurement of O+ and He+ is crucial for the determination of the ionosphere as the source of these particles. In Interplanetary Space the determination of the ionic charge allows to distinguish between two different sources of energetic particles: the solar wind with heavy ion charge states compatible with coronal temperatures of ~1-3 MK, and interstellar neutrals, singly ionized in the inner heliosphere (pickup ions) and then accelerated to energies of 10s MeV/nuc at the termination shock of the heliosphere or beyond. In this paper we provide an overview of the experimental techniques, and discuss how ionic charge measurements help to better understand the acceleration of ACRs and solar energetic particles (SEP). The measurements of the mean ionic charge of SEPs over the large energy range of ~0.1 to 70 MeV/nucleon allows, for example, to distinguish between acceleration in the high corona and interplanetary space and acceleration at low coronal altitudes where charge stripping effects are important and result in a specific signature of the energy dependence of the mean ionic charge at energies below 1 MeV/nucleon.
Created 2015-03-09 13:43:39 by Mats HolmstrÃ¶m Last changed 2015-03-12 15:32:13 by Mats HolmstrÃ¶m