Validity of quasilinear theory: refutations and new numerical confirmation

Nicolas Besse, Yves Elskens, D F Escande, Pierre Bertrand
2011 Plasma Physics and Controlled Fusion  
Over almost three decades an unsettled controversy developed about the validity of quasilinear (QL) theory for describing the weak warm beam-plasma instability in the chaotic saturation regime. This work deals both analytically and numerically with this issue. It is shown analytically that there is no mode coupling in the saturation regime of the instability where a plateau is present in the tail of the particle distribution function. This invalidates several analytical works trying to prove or
more » ... trying to prove or to contradict the validity of quasilinear estimates in the strongly nonlinear regime of the weak warm beamplasma instability. Self-consistent numerical simulations of the weak warm beamplasma instability within the Vlasov-wave description show that QL theory remains valid in the strong chaotic diffusion regime. However there is a non-QL regime before saturation, which confirms another analytical work and contradicts a later one, but confirms a previous numerical simulation.
doi:10.1088/0741-3335/53/2/025012 fatcat:3h6fqk2565fkxj6zrks3trnpge