  Data-driven techniques developed in recent years for the discovery of
equations describing complex physical phenomena open unique opportunities for
plasma physics. These methods allow getting insights into the processes
difficult for analytical description. Since gas discharges can be represented
as complex electrical circuits consisting of impedances and capacitances, it
looks natural to use the data-driven techniques to study their complex
dynamics. In the present paper, the sparse identification of nonlinear dynamics
(SINDy) method is applied to analyze the self-oscillations of direct current
discharge in argon. It is obtained that the third order polynomials describe
best the oscillations of the discharge voltage and current. They allow an
accurate capturing of the oscillations amplitudes as well as the harmonics of
these oscillations. To understand the physical meaning of each term, an
analytical model is presented which describes the discharge self-oscillations.
