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 upsilon(p) produces a Cherenkov wake of Langmuir waves behind itself, whenever upsilon(p) much greater than upsilon(Te). This makes the interaction range of suprathermal charged particles of the order of (upsilon(p)/upsilon(Te))lambda(De), much larger than the static screening length [Peter, Th., J. Plasma Phys. 44, 269 (1990)], the Debye radius lambda(De). 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., Phys. Rev. E47, 3574 (1993); Lontano, M. and Raimondi F., Phys. Rev. E51, R2755 (1995)]. 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.