  In collision-poor space plasmas protons with an excess of kinetic energy or
temperature in direction perpendicular to background magnetic field can excite
the electromagnetic ion cyclotron (EMIC) instability. This instability is
expected to be highly sensitive to suprathermal protons, which enhance the
high-energy tails of the observed velocity distributions and are well
reproduced by the (bi-)Kappa distribution functions. In this paper we present
the results of a refined quasilinear (QL) approach, able to describe the
effects of suprathermal protons on the extended temporal evolution of EMIC
instability. It is thus shown that suprathermals have a systematic stimulating
effect on the EMIC instability, enhancing not only the growth rates and the
range of unstable wave-numbers, but also the magnetic fluctuating energy
density reached at the saturation. In effect, the relaxation of anisotropic
temperature becomes also more efficient, i.e., faster in time and closer to
isotropy.
