[en] The present study was undertaken to provide insight into the mechanisms that govern the evolution of microstructure in Ni powder during cryomilling with nitride particles. The AlN particles are distributed in Ni powder particles after cryomilling, and the particles with initial size of 2 μm are fractured into smaller size, 50∼300 nm, during cryomilling. The distribution of particles is uniform, and some extremely small particles, size range of ∼20 nm, are also observed by TEM after cryomilling. With addition of AlN particles, the Ni powder particle size after cryomilling is reduced, and contamination of iron and gaseous atoms, N and O, is increased. For the grain size of Ni, the present results show that, in the presence of 2 wt% (5 vol%) AlN particles, the Ni grain size is reduced to 37 nm after 8 h of cryomilling. In contrast, the grain size of Ni cryomilled under identical conditions but without particles exceeded 100 nm. In terms of volume fraction, the results show an increase in the rate of grain size refinement with increasing volume fraction of AlN particles for the range studied, i.e. 1.2-5.0 vol%. The grain size is also reduced to 25 nm with increasing impeller speed up to 340 rpm, which provides higher kinetic energy, and longer cryomilling time of 20 h. This observation is rationalized on the basis of a mechanism involving the interactions of dislocations with hard, non-deformable nitride particles, and thermally induced dislocation generation due to the thermal expansion coefficient difference between the Ni matrix and the nitride particles

[en] An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22 cm diameter and 30 cm length, purifies an airflow rate of 5000 lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application

[en] A high temperature of a steam torch ensures an efficient gasification of low-grade coals, which is comparable to that of high-grade coals. Therefore, the coal gasification system energized by microwaves can serve as a moderately sized power plant due to its compact and lightweight design. This plasma power plant of low-grade coals would be useful in rural or sparsely populated areas without access to a national power grid.

[en] A comprehensive decontamination scheme of the chemical and biological agents, including airborne agents and surface contaminating agents, is presented. When a chemical and biological attack occurs, it is critical to decontaminate facilities or equipments to an acceptable level in a very short time. The plasma flame presented here may provide a rapid and effective elimination of toxic substances in the interior air in isolated spaces. As an example, a reaction chamber, with the dimensions of a 22 cm diameter and 30 cm length, purifies air with an airflow rate of 5000 l/min contaminated with toluene, the simulated chemical agent, and soot from a diesel engine, the simulated aerosol for biological agents. Although the airborne agents in an isolated space are eliminated to an acceptable level by the plasma flame, the decontamination of the chemical and biological agents cannot be completed without cleaning surfaces of the facilities. A simulated sterilization study of micro-organisms was carried out using the electrolyzed ozone water. The electrolyzed ozone water very effectively kills endospores of Bacillus atrophaeus (ATCC 9372) within 3 min. The electrolyzed ozone water also kills the vegetative micro-organisms, fungi, and virus. The electrolyzed ozone water, after the decontamination process, disintegrates into ordinary water and oxygen without any trace of harmful materials to the environment

[en] The description and investigation of a large-volume plasma source at low pressure are presented in this article. This new system is a modification of large-volume plasma source operated by thermionic filaments, and is an application of multi-needle plasma at atmospheric pressure stabilized by the flowing channel of a working gas through a high-voltage electrode operated by a AC (20 kHz) power supply. The weakly magnetized plasma is created by direct ionization of the background gas by low-energy electrons generated from multi-needle plasma, which are annularly arranged at one end of a cylindrical chamber. The bulk plasma experiment is conducted in the cylindrical stainless steel chamber with a radius of 0.5 m and a length of 3 m. Also, presented are preliminary experimental results of multi-needle plasma at atmospheric pressure