Development and Research of High-Enthalpy Multi-Functional Wind Tunnels Using Quasi-Steady MW-Class Arc Heaters

本文介绍了一种用于材料加工和气动加热模拟等的准稳态高焓等离子体风洞。电弧加热器工作电流为3-10 kA，工作气体为Ar、H_2、N_2和NH_3。产生的等离子体特性与静电探针测量。电子温度在50 mm的下游位置处为约5eV，并且离子数密度为10 μ cm<16>-3量级<-3>。结果，在轴上产生了高温、高密度和高速等离子体。针对电弧加热器在陶瓷涂层中的应用，研制了一种阴极覆盖陶瓷材料的烧蚀型电磁加速电弧加热发生器。在5-10 kA的Ar的100次发射操作中，陶瓷盖的烧蚀率范围为1.1至7.5 mg/shot。MPD等离子喷涂结果表明，获得了致密均匀的陶瓷膜，维氏硬度在1200以上。从XPS谱图来看，涂层的Si/Al峰面积比几乎与陶瓷原料相同，Al和Si的价数没有变化。因此，准稳态高焓等离子体发生器被发现具有很高的潜力，材料加工和应用到空气动力学领域。

A quasi-steady high-enthalpy plasma wind tunnel was developed for material processing and aerodynamic heating simulation etc. The arc heater was operated with discharge currents of 3-10 kA with working gases of Ar, H_2, N_2 and NH_3. Generated plasma characteristics were measured with an electrostatic probe. The electron temperature was about 5 eV at a downstream position of 50 mm, and the ion number density was the order of 10^<16> cm^<-3>. As a result, high-temperature high-density and high-velocity plasmas were created on the axis. For applications of the arc heater to ceramic coatings, an ablation-type electromagnetic-acceleration-type arcjet generator with a cathode covered with ceramic materials was developed. In 100-shot operations for Ar at 5-10 kA,the ablation rates of the ceramic covers ranged from 1.1 to 7.5 mg/shot. The MPD plasma spraying showed that a dense uniform ceramic film with above 1200 Vickers hardness was deposited. From the XPS spectra, the peak area ratio of Si/Al for the coating almost equaled that for the raw ceramic material, and the valence numbers of Al and Si did not change. Consequently, the quasi-steady high-enthalpy plasma generator was found to have a high potential for material processing and for applications to aerodynamic areas.