An analysis is presented of an experimental study of the scattering of microwaves by density fluctuations due to the current‐driven ion acoustic wave instability in a toroidal plasma confinement device, the FM‐1 spherator. It is found that the instability exists only in the collisional regime (where &ngr;ef≳&ohgr;be) and it is inhibited (i.e., quenched by two orders of magnitude) in the trapped‐electron banana regime (where &ngr;ef<&ohgr;be). Further, it is found that for two different values of the ratio of the trapped to untrapped electron number density (i.e., for both 70% and 40% mirror trapping) this inhibition always starts to occur when &ngr;ef≈&ohgr;be. Finally, it is shown that the nature of this inhibition is in general agreement with the recent theoretical notion that in the banana regime the entire Ohmic heating current is carried only by the freely circulating electrons.