Theoretical interpretation of streak camera records of rapidly developing discharges

A theory of image analysis from a photographic record of a discharge obtained with a streak image converter is proposed to obtain quantitative conversion of photographic density records into electric magnitudes of the discharge. A correlation is made between the derivatives of the blackening density of the film and the local current density which allows the deduction of the fundamental parameters, i.e. the electric field and electron density. It is thus possible to establish the spatio-temporal distribution of the perturbation of the space-charge field and the evolution of electronic density. This is applied to the case of a rapidly developing discharge in nitrogen-methane submitted to an overvoltage.