Translated Abstract
Because of the significant advantages in speeding shells, reducing the temperature sensitivity and controlling the launching process, the Electro-Thermal-Chemical-Gun using plasma ignition is considered to be the first new type of weapons used in actual fighting. The firing process of ETCG includes complex physical and chemical interactions between the plasma and capillary, the plasma jet and propellants. In this peper, we investigated the academic model of capillary discharge plasma jet and its features, the results are important for further understanding of the mechanism of plasma ignition. This paper established a two-dimensional MHD model for the capillary discharge plasma. The main features of this model are that, the ablation products are considered in the mass, momentum and energy conservation equations. The energy injected by the ablation products is calculated by the method of thermodynamic enthalpy and considered in the energy conservation equation. Considering the the effects caused by ablation and deposition, we adopt a dynamical model to describe the interaction between the plasma and the capillary wall. The capillary material is polyethylee, the current is 2291A in the experiment, the results show that the pressure in the capillary increase from 1atm to 39atm from the outlet to interior in the axial direction, and the ablation process in the capillary wall turned to deposition gradually. The velocity of the plasma at the outlet reaches 10km/s, and the value changes significantly at the outlet.Besides the numerical simulation, we also made an experimental investigation of transient plasma jet in open air with the global objective of gaining insights from parametric studies on our test platform. Various of diagnostics including high-speed photography, pressure mesurements and velocity mesurments have been used in our system. From the results we can see that, under the working voltage of 6kV, the average velocity in open air reaches 600m/s. The peak pressure in the center of the plasma reaches 5.1MPa at the test point 50mm from the nozzle, and the peak pressure decreases to 1.5MPa at the test point 15mm away from the jet center.In additon, the impact of the capillary size on the consistency of the plasma jet is analyzed in this paper, and a proposal to improve the insulation of the plasma generator is proposed in this paper as well. Experimental results show that, under the working voltage of 6kV, the length and diameter of the pelythylene capillary is 26mm and 3.2mm, the duration of the discharge process reaches 0.82ms, and the consistency of the plasma jet in different discharge experiments performs well. Under the working voltage of 18kV, when the overlap length between the PTFE insulation tube and the epoxy insulation tube increases from 2mm to 10mm, the electric field strength value in the 0.5mm gap decreases from 5.3�V/m to 4.05�V/m, and the insulation performance of the generator has been improved.
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