[en] Lower hybrid current drive experiments on the Petula B tokamak have already shown strong modifications of the plasma behaviour when a fast electron population is sustained by lower hybrid waves. The main response of the plasma to the absorbed power is the current but various other responses can be analyzed. This paper reports an experimental and theoretical study on the use of the Electron Cyclotron Emission as a diagnostic for the absorbed H.F. power. The current, the conduction and the saturation of the absorption are observed and interpreted