This paper assigns optimum capillary discharge characteristics with respect to reaching the maximum emission gain on wavelength l = 18.2 nm and corresponding to Balmer α transition H-like carbon. The computer modelling of the capillary discharge evolution is carried out using the NPINCH programme, using a one-dimensional physical model based on MHD equations. The information about the capillary discharge evolution is processed in FLY, FLYPAPER, FLYSPEC programmes, enabling the population to be modelled on specific levels during capillary discharge.