Stability of Bilateral Discharge in the Ring Laser

A method has been developed for determining the threshold for the development of instability of a gas discharge in a ring helium-neon laser, taking into account the distributed capacitance “positive pole – grounded shield”. In the developed approach to stability analysis, the positive discharge of the column is replaced by an equivalent circuit, a series connection of a negative dynamic resistance ρ and balanced RL-circuits. An equivalent circuit can be synthesized by experimental studies of the linear response of a gas-discharge plasma to weak harmonic perturbations, presented in the form of frequency dependences of the complex resistance Z of a positive column. The calculation of the instability development threshold in the electrical circuit of a two-arm discharge only on the basis of the experimentally recorded frequency dependence of the complex resistance of the positive column does not allow one to extend the quantitative analysis to conditions outside the range of conditions in which the measurements were performed. To overcome this limitation, which hinders the search for the operating current, in which the development of instability is excluded for the entire temperature range of operation of ring helium-neon lasers, a model has been developed that describes the positive column of the gas discharge. The boundary of the unstable state of a two-arm gas discharge in the space of parameters is found: resistance of ballast resistors, temperature, mounting capacitance. The results obtained make it possible to maintain a two-arm DC discharge in a given range of temperature variation.