In the present paper, a physical model is proposed for reducing the problem of the drag reduction of an attached bow shock around the nose of a high-speed vehicle with on-board discharge, to the problem of a balance b...In the present paper, a physical model is proposed for reducing the problem of the drag reduction of an attached bow shock around the nose of a high-speed vehicle with on-board discharge, to the problem of a balance between the magnetic pressure and gas pressure of plane shock of a partially ionized gas consisting of the environmental gas around the nose of the vehicle and the on-board discharge-produced plasma. The relation between the shock strength and the discharge-induced magnetic pressure is studied by means of a set of one-fluid, hydromagnetic equations reformed for the present purpose, where the discharge-induced magnetic field consists of the electron current （produced by the discharge）-induced magnetic field and the partially ionized gas flow-induced one. A formula for the relation between the above parameters is derived. It shows that the discharge-induced magnetic pressure can minimize the shock strength, successfully explaining the two recent experimental observations on attached bow shock mitigation and elimination in a supersonic flow during on-board discharge [Phys. Plasmas 9 （2002） 721 and Phys. Plasmas 7 （2000） 1345]. In addition, the formula implies that the shock elimination leaves room for a layer of higher-density plasma rampart moving around the nose of the vehicle, being favourable to the plasma radar cloaking of the vehicle. The reason for it is expounded.展开更多
A series of chemicals are designed and prepared. With the method of thermodynamics, the average electron densities of the plasmas generated by burning chemicals are calculated. The reflection and attenuation of the mi...A series of chemicals are designed and prepared. With the method of thermodynamics, the average electron densities of the plasmas generated by burning chemicals are calculated. The reflection and attenuation of the microwaves, in a frequency band of 2 GHz to 15 GHz, by the plasma are measured. The results of measurements indicate that the plasma can absorb the energies of the microwaves in a broad band and reflect them faintly. Moreover, theoretical discussion reveals that the electron-neutral collision is the major factor that results in the absorption in the wide band. By using Appleton equations, average collision frequencies and electron densities are calculated from the attenuations of microwaves.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 40390150 and 10005001）.
文摘In the present paper, a physical model is proposed for reducing the problem of the drag reduction of an attached bow shock around the nose of a high-speed vehicle with on-board discharge, to the problem of a balance between the magnetic pressure and gas pressure of plane shock of a partially ionized gas consisting of the environmental gas around the nose of the vehicle and the on-board discharge-produced plasma. The relation between the shock strength and the discharge-induced magnetic pressure is studied by means of a set of one-fluid, hydromagnetic equations reformed for the present purpose, where the discharge-induced magnetic field consists of the electron current （produced by the discharge）-induced magnetic field and the partially ionized gas flow-induced one. A formula for the relation between the above parameters is derived. It shows that the discharge-induced magnetic pressure can minimize the shock strength, successfully explaining the two recent experimental observations on attached bow shock mitigation and elimination in a supersonic flow during on-board discharge [Phys. Plasmas 9 （2002） 721 and Phys. Plasmas 7 （2000） 1345]. In addition, the formula implies that the shock elimination leaves room for a layer of higher-density plasma rampart moving around the nose of the vehicle, being favourable to the plasma radar cloaking of the vehicle. The reason for it is expounded.
文摘A series of chemicals are designed and prepared. With the method of thermodynamics, the average electron densities of the plasmas generated by burning chemicals are calculated. The reflection and attenuation of the microwaves, in a frequency band of 2 GHz to 15 GHz, by the plasma are measured. The results of measurements indicate that the plasma can absorb the energies of the microwaves in a broad band and reflect them faintly. Moreover, theoretical discussion reveals that the electron-neutral collision is the major factor that results in the absorption in the wide band. By using Appleton equations, average collision frequencies and electron densities are calculated from the attenuations of microwaves.
