Influence of the hollow cathode shape on the plasma parameters of a non-self-sustained glow discharge with external electron injection

Abstract

This work is devoted to the study of low-temperature plasma generation processes in extended and complex hollow cathodes. The plasma generation system is a two-discharge system, where the main discharge is ignited inside a hollow cathode, at one end of which the anode of the main discharge is located, and at the opposite end there is a grid through which additional electrons are injected from the auxiliary discharge plasma. The paper shows the possibility of generating a homogeneous plasma inside a curved (at 90°) hollow cathode and inside two hollow cathodes arranged in parallel. The length of the cathodes was 300 mm with an inner diameter of 25 mm. The pressure in the discharge system was up to 1 Pa at a voltage of up to 300 V and a current of up to 10 A. The parameters of the main discharge plasma were measured using double Langmuir probes installed along the hollow cathodes. The measurement results showed that the coefficient of plasma concentration inhomogeneity is ±23% in a curved hollow cathode, and up to ±35% along each cavity in a discharge system with two parallel cathodes, and the deviation from the average value of the plasma concentration in comparison of two parallel hollow cathodes amounted to ±11%. The results obtained can be useful for creating low-temperature plasma generation systems for the implementation of ion-plasma processing of the inner surface of extended metal products of complex shape in order to increase their service life by a factor.