A TIME-DEPENDENT MODEL FOR HIGH-PRESSURE DISCHARGES IN NARROW ABLATIVE CAPILLARIES

A time-dependent quasi-one-dimensional model is developed for studying high-pressure discharges in ablative capillaries used, for example, a s plasma sources in electrothermal launchers. The main features of the model are (i) consideration of ablation effects in each of the contin uity, momentum and energy equations; (ii) use of a non-ideal equation of state; and (iii) consideration of space- and time-dependent ionizat ion. Time-dependent spatial profiles of all plasma characteristics are computed, using self-consistent boundary conditions at both ends of t he ablative capillary. The reliability of the numerical solution is pr oved by checking the satisfaction of mass and energy conservation laws . The calculations show that a high-pressure (up to about 4.5 kbar in this case), sufficiently warm (about 50000 K) plasma could be obtained using ablative capillary discharges. Some of the well-known experimen tal features of these kind of discharges, such as the presence of quas i-steady-state behaviour over a significant fraction of the discharge duration, as well as the extended spatial isothermicity of the plasma, are confirmed by the model and the numerical solutions obtained.