Kinetic solitary electrostatic structures in collisionless plasma: Phase-space holes

The physics of isolated plasma potential structures sustained by a deficit of phase-space density on trapped orbits, commonly known as electron or ion holes, is reviewed. The principles of their equilibria are explained and illustrated, and contrasted with solitons. A review of literature mostly from prior to 2016 highlights the key historical developments of the field. Progress since, especially in hole acceleration, stability, and multidimensional effects, is summarized in more detail.