  Relaxations of localized over-density in a plane transverse to the magnetic
field are numericallyinvestigated under the effect of drift-wave and
interchange drives in SOL conditions. Such a controlleddeparture from
thermodynamic equilibrium allows the investigation of fundamental processesat
play in cross-field transport. Interchange instabilities generate ballistic
outward radial flux withlow amplitude zonal flow patterns, whereas drift-wave
instabilities result in symmetric radial fluxwith large amplitude zonal flow
patterns. When both instabilities are considered, the combinedeffects tend to
favor drift-waves, leading to a weaker outward flux with larger zonal flow
patterns.
