Ar Plasma Jet Research Articles

Mixing and magnetic effects on a nonequilibrium argon plasma jet

Effects of gas admixture and of an applied magnetic field on a nonequilibrium Ar plasma jet are investigated experimentally. The maximum gas temperature and gas velocity are observed in the core region of an Ar/He plasma due to the small density, the large thermal conductivity and Mach number effect of He. Furthermore, their radial gradients become very steep in the applied magnetic field. In contrast, the gas temperature and gas velocity of an Ar/N 2 plasma jet are not so high and their radial gradients are moderate, because of the energy loss needed to dissociate N 2 gas in the core region and of the active thermal diffusion in the radial direction. Electron number density is larger in the case of an Ar/Ar plasma jet or an Ar/He plasma jet compared with that of an Ar/N 2 plasma, since N 2 gas dissociates before ionization. It is shown that the admixing of He or N 2 gas influences controllably the flow and temperature fields of a nonequilibrium Ar plasma jet also in an applied magnetic field.

Numerical Simulation of Mixing Effect on a Non-equilibrium Plasma Jet in an Applied Magnetic Field.

The present study describes the numerical model to control the thermofluid characteristics and plasma parameters of a non-equilibrium plasma jet by mixing with the secondary gas in an applied magnetic field. The velocity and the gas temperature fields and also the plasma parameters in a non-equilibrium Ar/He plasma jet are obtained by solving the axisymmetric turbulent 2-D MHD equations taking into account the variable transport properties of gas mixtures and using k-e model, two-temperature model coupled with Ohmic equations. The concentration field is also evaluated using species conservation equation. It can be examined numerically how the thermofluid and diffusion characteristics, and plasma parameters of a non-equilibrium Ar plasma jet are enhanced or controlled by mixing with He and by applying a magnetic field.

Study of Properties of Ar Micro Arc Plasma Jets for Fine Cutting with Synthetic Spectra Method.

Based upon a collisional and radiative process theory, and synthetic spectra for argon plasmas, the experimental method for spatial properties of Ar plasma jets was presented, and applied to diagnostics for micro Ar plasma jets for fine cutting. A plasma torch had a nozzle of 0.7 mm in diameter and a discharge length of 2 to 10 mm, and was operated with an arc current of 10 to 30 A. Data from a CCD image processor and Mach-Zehnder interferometer were dealt with an Abel transformation to obtain true spacial profiles of electron density and temperature, and heavy particle temperature. Electron temperature in the main flow was found to be about 12 000 to 13 500 K, electron density of an order of 1016 cm-3, both increasing with an arc current. It was also found that heavy particle temperature was significantly lower than electron temperature in the nozzle exit region and increased to coincide with electron temperature downstream. Experimental relation of electron temperature and density could be approximated well by that calculated from steady-state collisional and radiative processes.

Effect of Chlorine Species on Diamond Deposition from Plasma Jets with Chlorobenzenes as Carbon Sources

The effect of chlorine species on diamond deposition with chlorobenzenes as carbon sources was investigated. Diamond deposited from an Ar/chlorinated benzenes/ plasma jet, on which Cl species were adsorbed, was exposed to Ar and plasma jets and diamond deposited from an plasma jet, on which H species were adsorbed, was exposed to an plasma jet. During the exposure, HCl species were observed in the plasma jets by means of optical emission spectroscopy. By the exposure of samples to the and Ar plasma jets, adsorbed Cl species disappeared. By the exposure of the H adsorbed sample in the plasma jet, the surface was covered with graphite or amorphous carbon. The abstraction of surface adsorbed Cl species by H atoms, the dehydrochlorination reaction on the surface and the abstraction of surface adsorbed H species by Cl species would occur in the diamond deposition from the plasma jets with chlorobenzenes as carbon sources. Excess amounts of Cl species would foster the nondiamond deposition.

窒素-アルゴン混合ガスプラズマジェットによる窒化ホウ素薄膜の生成

窒素-アルゴン混合ガスプラズマジェットによる窒化ホウ素薄膜の生成

ダイバータ板用タングステン‐銅接合構造の熱疲労に対する健全性試験 Ｉ ロー付け試験片の結果

The tungsten-copper (W-Cu) duplex structure for use as a divertor plate is a reference design concept in the FER (Fusion Experimental Reactor). In the present study, durability tests of the W-Cu duplex structures against thermal fatigue were carried out. The W disk was bonded to the Cu disk by means of brazing. The W surface of the test piece was periodically exposed to a high temperature Ar plasma jet. Before and after the tests, the specimens were examined with the aid of a scanning electron microscope and the Knoop hardness was measured. Grain boundary cracks were observed in the W with a small quantity of Ni and P for 200 and 1, 100 thermal cycles. But, microcracks were not observed in the W with an extremely small quantity of impurities, even for 3, 700 thermal cycles. Microcracks were observed in the brazing material of this specimen. None of them were broken. Consequently, it is found that the bonding method of the brazing is effective and that the W-Cu duplex structure is fully resistant against thermal fatigue.