Cosmic-Ray-modified and driven instabilities

These lectures address the effects of Cosmic Rays over macro-instabilities which develop in the interstellar medium and the micro-instabilities the particles are able to trigger themselves. The lectures are centered on the derivation of linear growth rates but also discuss some numerical simulations addressing the issue of magnetic field saturation. A particular emphasis is made on the streaming instability, an instability driven by anisotropic cosmic-ray distributions.
Comment: To appear in Foundations of Cosmic Ray Astrophysics, Proceedings of the International School of Physics "Enrico Fermi", Course 208, Varenna, 24 - 29 June 2022, edited by F. Aharonian, E. Amato, and P. Blasi