Collective effects in the slowing down of heavy ions in a collisionless plasma

Several aspects of the interaction of fast heavy ions with a collisionless plasma are reviewed paying particular attention to the collective character of the physical processes involved. A fast ion moving into a classical plasma with velocity vp produces a Cherenkov wake of Langmuir waves behind itself, whenever vp  vTe. This makes the interaction range of suprathermal charged particles of the order of (vp/vTe)λDe, much larger than the static screening length [Peter Th, 1990 J. Plasma Phys. 44 269], the Debye radius λDe. If we consider an ensemble of several ions sufficiently, close to each other, their motion will be dominated by two-ion correlations [D'Avanzo J, Lontano M and Bortignon P F, 1993 Phys. Rev. E 47 3574; Lontano M and Raimondi F, 1995 Phys. Rev. E 51 R2755]. The collective character of the interaction of correlated fast ions in a plasma is investigated. The nonlinear regime of ion-plasma interaction is also briefly tackled.