Cluster multipoint observations of ionic structures in the plasmasphere by CIS and comparison with image-EUV observations and with model simulations

摘要: The 4 Cluster spacecraft orbit the Earth in a highly eccentric polar at RE perigee, and this permits them to sample ring current, radiation belts outer plasmasphere. Data provided by Ion Spectrometry (CIS) instruments are used analyze crossings of CIS is capable obtaining full three-dimensional ion distributions (about 0 40 keV/q) with time resolution one spin (4 sec) mass-per-charge composition determination. In addition Retarding Potential Analyzer (RPA) allows more accurate measurements about 0-25 eV/q energy range, covering plasmasphere domain. low-energy distribution functions, obtained CIS-RPA during perigee passes, allow reconstruct statistically plasmapause morphology dynamics, but they also reveal new interesting features. discrimination capability reveals how density profile different for each main species (H+, He+, O+): H+ He+ present mostly similar profiles; O+, however, not observed as trapped plasmaspheric population altitudes. Low-energy O+ mainly upwelling ion, on auroral field lines. Detached events some passes. bi-directional functions these detached populations us distinguish from populations. observations position have been simulated an interchange instability numerical model deformations, reproduces very satisfactory way observations. local correlated global images plasmasphere, EUV instrument onboard Image, event where were within field-of-view EUV. show that difference between two was temporal (boundary motion). They thus necessity correlating images, complementarity approaches; giving "ground truth" (including plasma composition, etc.) allowing put into context, deconvolve spatial effects.