Abstract <p>This paper presents a technique and an experimental setup that implements it for the optical diagnostics of pulsed plasma initiated by YAG:Nd³⁺ laser radiation in a laser-controlled high-voltage gas switch, which is used as a primary switch of a RADAN-type high-current high-voltage pulsed electron accelerator–generator. The studies were performed in a natural atmosphere. The first results of measurements of the dynamics of the laser-radiation absorption coefficient in a plasma produced using this installation. These data indicate the implementation of the conditions for the nonlinear absorption of laser radiation by plasma at excitation energy densities higher than 240 J/cm². They will make it possible to develop recommendations for selecting the gas-gap triggering parameters in order to minimize jitter.</p>