Role of on-board discharge in shock wave drag reduction and plasma cloaking

In the present paper, a physical model is proposed for reducing theproblem of the drag reduction of an attached bow shock around thenose of a high-speed vehicle with on-board discharge, to the problemof a balance between the magnetic pressure and gas pressure of planeshock of a partially ionized gas consisting of the environmental gasaround the nose of the vehicle and the on-board discharge-producedplasma. The relation between the shock strength and thedischarge-induced magnetic pressure is studied by means of a set ofone-fluid, hydromagnetic equations reformed for the present purpose,where the discharge-induced magnetic field consists of the electroncurrent (produced by the discharge)-induced magnetic field and thepartially ionized gas flow-induced one. A formula for the relationbetween the above parameters is derived. It shows that thedischarge-induced magnetic pressure can minimize the shock strength,successfully explaining the two recent experimental observations onattached bow shock mitigation and elimination in a supersonic flowduring on-board discharge [Phys. Plasmas 9 (2002) 721 andPhys. Plasmas 7 (2000) 1345]. In addition, the formulaimplies that the shock elimination leaves room for a layer ofhigher-density plasma rampart moving around the nose of the vehicle,being favourable to the plasma radar cloaking of the vehicle. Thereason for it is expounded.