Analysis of plasma critical flow in a combined discharge capillary ablative pipe system

Abstract

The system of a high pressure discharge capillary connected to an ablative pipe is shown here to be an efficient and convenient plasma source. The characteristics of the source (mass and energy fluxes) are determined by the Joule energy supplied to the discharge section as well as by the wall material and, geometrical parameters of the discharge capillary and the ablative pipe. For a given wall material and fixed geometrical characteristics of the capillary, a large range of exit plasma parameters values can be obtained by varying either the length of the ablative pipe or the electrical current carried by the discharge. Useful information for the design of the proposed plasma source is given. It is based on consistent numerical solution of the quasi onedimensional continuity momentum and energy equations with non-ideal state equation and non-uniform ionization degree for the combined discharge unit and ablative pipe.

Analysis of powder particle acceleration and heating processes in a discharge capillary - ablative pipe device

“…Our claim is well supported by the results reported in [2] concerning the parameters of the plasma reached in the capillary-ablative pipe system. Depending on the system geometry and input power, temperatures higher than 1 eV (up to 4-5 eV), high densities and velocities around 10 km s −1 can be reached.…”

“…The capillary-ablative pipe system shown in figure 1 has been proposed as a high-power pulsed source of hightemperature high-density plasma [1,2]. As a result of the high temperature, the plasma sound velocity is also high.…”

“…At the same time, due to the large plasma pressure usually developed in this kind of device, the flow is sonic at its open end, leading to large flow velocities inside the device itself. A theoretical model for the plasma flow in such a device has been presented [2]. Using this model the effect of the device geometry change (such as various radii and lengths of the capillary-ablative pipe system) on the thermodynamic and hydrodynamic parameters of the plasma flux leaving the system has been studied.…”

“…This is true for the characteristics of the plasma jet as well as the interaction of powder particles with the plasma. This study will try to address these two issues in the frame of the consistent model proposed in [9][10][11] for the plasma flow in ablative capillaries and extended in [2] for the capillary-ablative pipe system. The importance of this kind of study is emphasized by the fact that, due to the specific characteristics of the ablative discharges in opaque tubes, it is very difficult to obtain reliable values for the plasma's main physical parameters by experimental measurements.…”

A Study on the Efficient Method for the Solution of the Saha Equation in the Numerical Simulation of Capillary Discharge

“…Due to the computational amount, the simulation of capillary discharge usually takes longer time compared with conventional computational fluid dynamics problem. Particularly, in the cases that a long tube might be joint with the exit of the capillary to serve as the barrel or cathode or other purposes [4,16,17], the larger computational region would increase the simulation runtime further. In this paper, two methods are introduced for a better computational efficiency including optimizing the coefficient introduced in the iteration equation and setting the iteration initial value dynamically.…”