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Abstract. Super-elastic collision is an abnormal collisional process, in which some particular mechanisms cause the kinetic energy of the system increasing. Most studies in this aspect focus on solid-like objects, but they rarely consider gases or liquids, as the collision of the latter is primarily a mixing process. With cross-field diffusion being effectively prohibited, magnetized plasmoids are different from ordinary gases. But it remains unclear how they act during a collision. Here we present the global picture of a unique collision between two coronal mass ejections in the heliosphere, which are the largest magnetized plasmoids erupting from the Sun. Our analysis for the first time reveals that these two magnetized plasmoids collided like solid-like objects with a 73% likelihood of being super-elastic. Their total kinetic energy surprisingly increased by about 6.6% through the collision, which significantly influenced the dynamics of the plasmoids.

In this paper, ten CME events viewed by the STEREO twin spacecraft are analyzed to study the deflections of CMEs during their propagation in the corona. Based on the three-dimensional information of the CMEs derived by the graduated cylindrical shell (GCS) model [Thernisien et al., 2006], it is found that the propagation directions of eight CMEs had changed. By applying the theoretical method proposed by Shen et al. [2011] to all the CMEs, we found that the deflections are consistent, in strength and direction, with the gradient of the magnetic energy density. There is a positive correlation between the deflection rate and the strength of the magnetic energy density gradient and a weak anti-correlation between the deflection rate and the CME speed. Our results suggest that the deflections of CMEs are mainly controlled by the background magnetic field and can be quantitatively described by the magnetic energy density gradient (MEDG) model.Comment: 19 pages, 20 figure

[1] In this study, we utilize a recently introduced relativistic kappa-type (KT) distribution function to model the omnidirectional differential flux of energetic electrons observed by the SOPA instrument on board the 1989-046 and LANL-01A satellites at geosynchronous orbit. We derive a useful correlation between the differential flux and the distribution of particles which can directly offer those best fitting parameters (e.g., the number density N, the thermal characteristic speed q and the spectral index k) strongly associated with evaluation of the electromagnetic wave instability. We adopt the assumption of a nearly isotropic pitch angle distribution (PAD) and the typical LMFIT function in the program IDL to perform a non-linear least squared fitting, and find that the new KT distribution fits well with the observed data during different universal times both in the lower and higher energies. We also carry out the direct comparisons with the generalized Lorentzian (kappa) distribution and find that kappa distribution fits well with observational data at the relatively lower energies but display deviations at higher energies, typically above hundreds of keV. Furthermore, the fitting spectral index k basically takes 4, 5 or 6 while the fitting parameters N and q are quite different due to different differential fluxes of electrons at different universal times. These results, which are applied to the case of a nearly isotropic PAD, demonstrate that the particle flux satisfies the power law not only at the lower energies but also at the relativistic energies, and the new KT distribution may present valuable insights into the dynamical features in those space plasmas (e.g., the Earth's outer radiation belts and the inner Jovian magnetosphere) where highly energetic particles exist.