Several aspects of the interaction of fast heavy ions with a collision
less 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 la
rger 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 b
e dominated by two-ion correlations [D'Avanzo, J., Lontano, M. and Bor
tignon, P. F., Phys. Rev. E47, 3574 (1993); Lontano, M. and Raimondi F
., Phys. Rev. E51, R2755 (1995)]. The collective character of the inte
raction of correlated fast ions in a plasma is investigated. The nonli
near regime of ion-plasma interaction is also briefly tackled.