Application of a weak-ionized plasma high-temperature flow for material development and treatment of hazardous substance, and its flow diagnostics

在9 kW的电能下，可以稳定地产生弱电离的高温氮等离子体流。本文采用光学诊断方法测量了氮分子的振动温度和转动温度T_2<vib>和T_3<rot>。马赫<rot>数为5和6时，T_分别为3，000 ±500 K和2，500 ±500 K。另一方面，<vib>在两种情况下，在整个流场中T_几乎是恒定的。认为氮分子与电子碰撞所需的时间和碰撞频率可能是其主要原因。暴露在等离子体流中的盘形黄铜中的铜和锌成分在空间上发生了急剧变化。此外，这种弱离子化的氮等离子体流被发现具有通过气体渗氮使钢变硬的能力。维氏硬度为230的钢变得更硬，维氏硬度值为630，并且钢的硬度也在空间上变化。利用电弧等离子体流装置对氮氧混合气体进行了电离，并利用Boltzmann方法对中性O I和N I原子进行了光学研究。测得O I和N I的激发温度分别为18,500 K和17,500 K。因此，自由电子的温度应该是18，000 ± 500 K。

Weak ionized high temperature nitrogen plasma flow could be generated stably with the electrical energy of 9 kW. Optical diagnostics for the flow field, where a blunt cylindrical body was set, was undertaken to measure vibrational and rotational temperatures of the nitrogen, T_<vib> and T_<rot>. T_<rot> was 3,000±500 K and 2,500±500 K for the case of Mach number 5 and 6, respectively. On the other hand, T_<vib> was almost constant in the whole flow field for the both cases. It is considered that the required time for a nitrogen molecule to collide with an electron and its collision frequency might be the major factors for the reason.Copper and zinc components of a disc-shaped brass, which was exposed in the plasma flow, was drastically changed spatially. Furthermore, this weak ionized nitrogen plasma flow was found to have the ability to make steel hard by the gas nitriding. The steel with the Vickers hardness of 230 changed to be harder with the Vickers value of 630, and hardness of the steel was also changed spatially. It also suggests that the ionized nitrogen flow can be utilized to product a functionally gradient material.Nitrogen and oxygen mixture was ionized by the arc-plasma flow facility and the neutral O I and N I atoms was investigated optically by the Boltzmann plots method. The excited O I and N I temperatures were delived to be 18,500 K and 17,500K, respectively. Therefore, the temperature of a free electron should be 18,000±500K.