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Electromagnetic acceleration plasma generators, which are called magneto-plasma-dynamic (MPD) arcjet generators, can produce higher-velocity, higher-temperature and higher-density plasmas than those of conventional thermal plasma torches, because MPD arcjet plasma is efficiently accelerated by electromagnetic body forces in MW-class input power operation. These properties are effective for deposition...
This review talk describes how basic science finds application in space, fusion, environmental remediation and plasma processing. Basic plasma science deals with a hierarchy of interactions from single particle to collective motion in a many-bodied system. The physics of wave-particle interaction stimulates new applications to fusion and space propulsion. Energetic neutralized MeV beams can be produced...
WC-Co/Ni-base self-fluxing alloy layers were successfully formed on steel substrates using an electron beam cladding process. The WC particles were densely and homogenously dispersed within the Ni-base self-fluxing alloy without porosities. The effect of the electron beam conditions on layer formation was investigated, and the cladding layer properties were examined by hardness tests, abrasive wear...
A novel high-density microwave plasma utilizing a spokewise antenna was produced and applied for high-rate and low-temperature deposition of hydrogenated microcrystalline silicon (μc-Si:H) film. The plasma maintains a uniform state, i.e., high electron density, n e >10 11 cm -3 and low temperature, T e of 2-2.5eV in pure Ar plasma over 20cm in a diameter...
Plasma melting is one of the best ways to treat effectively a wide variety of wastes. The present study is focused to develop a new plasma recycle process for hazardous wastes, especially for electroplating sludge, which contains several percentages of heavy metals such as Ni and Cr. In-flight treatments of electroplating sludge were made by DC non-transferred arc with different plasma environments...
The helium bubble formation in YAG laser weldment of helium-implanted austenitic stainless steel was investigated. The helium ion implantation was carried out at the acceleration voltage from 2 to 6MeV using an implantation apparatus. After the welding, helium bubbles were observed at the bond region, heat-affected zone and weld metal. The increase in the laser power caused the growth of helium bubble...
The injection of nitrogen ions into pure titanium has been performed by the plasma-based ion implantation with a negative voltage of 10kV, pulse width of 10μs and a repetition rate of 100Hz. The ESCA/AES analysis indicates the nitrogen deposition with a peak at 27nm from the surface and the formation of TiN. The dissolution current density of the implanted samples was decreased about two orders of...
An electron gun with a very simple structure is described as being suitable for the energy range from 2 to 10keV or more. The gun consists of a concave cold cathode and an anode with an extraction orifice, which are maintenance-free. Helium or hydrogen gas is filled with low pressure for operation in a condition called ''obstructed discharge (OD)''. The concave structure of the cathode converges the...
An attempt was made to develop an empirical relation for the arc voltage in relation to arc current and gas flow rate. Current-voltage characteristics of a non-transferred plasma torch operating with argon and argon+nitrogen was studied. The net power transferred to the plasma with an increase of the gas flow rate was observed. The increase was 12.83 and 15.53%, respectively for arc current of 212...
In the present research, a new method for a water treatment utilizing the discharge of bubbles in water is proposed. The radicals with short lifetime can be effective for water purification because the discharge is expected to occur inside the bubbles in water. Magnetic-pulse-compression pulsed-power generator was used as a repetitive power supply. The bubbles generated by a bubbling tube were passed...
Various metal nitride and oxide thin films were prepared using a shielded reactive vacuum arc deposition. The cathode materials used as metal ion sources were Al, Ti, Cu, Cr, and Zn. These nitride and oxide films were deposited in pure N 2 and O 2 gas flows, respectively. First, the films were deposited for a short period by both non-shielded and shielded methods, and the macrodroplet...
We investigated the effect of treatment temperature on the magnetic property of Fe-N gradient foils irradiated with nitrogen plasma. Fe-N gradient foils irradiated with nitrogen plasma were composed of -Fe 2-3 N, γ'-Fe 4 N and γ nitrogen austenite in α-Fe matrix. The outermost region of Fe-N foils was composed of various iron nitrides, and the inner region was composed...
This paper reports the results of fundamental experiments on a continuous-wave CO 2 laser thruster. The laser-sustained plasma (LSP) was maintained in the pressure ranging from 2 to 7atm with a laser power level of more than 300W. The location of LSP can be controlled by adjusting laser power and focus position. Thruster performance was evaluated by measuring thrust using a simple thrust stand...
An experimental study was performed to evaluate the feasibility of DC arcjet/plasma jet operation at very low-power levels ranging from 40 to 90W, using nozzles with different materials and geometries. Nitrogen gas was used as the propellant. The thermal characteristics were evaluated for conventional nozzles and partially insulated nozzles, consisting of a ceramic insulator and a tungsten anode....
Polymer films containing C x F y have been deposited in Fluorinert vapor (C 7 F 16 ) plasmas. The spatial and temporal evolution of optical emission of CF 2 and C 2 radicals was monitored and kinetics of the C 7 F 16 decomposition process was discussed. The films were deposited on stainless steel, glass, molybdenum and silicon...
For small and dense dusts, using the fluid model, the distribution and suspension of dust particles under the action of electrostatic, gravitational and ion-drag forces are investigated in the plasma sheath. It is shown that competition among the forces results in spatial oscillations of the particle distribution. However, for large and rare dusts using the isolated particle model the suspension of...
High-power rf heating in the ion cyclotron range of frequency (ICRF) has been carried out in a divertor plasma simulator NAGDIS-II. The main objective of the present work is to produce high heat flux plasmas for fundamental studies of the divertor plasmas in magnetically confined fusion devices. Waves are excited by phased-loop antenna array in a frequency range between 0.5 and 1.5MHz. Inverter power...
By means of gas tunnel-type plasma spraying, a high-hardness zirconia coating could be obtained at a short spraying distance. For example, Vickers hardness of zirconia coating was H v =1050 at the spraying distance of L=30mm, when the power input was P=20kW. This high-hardness coating had a hardness layer near the surface. In this paper, the effect of heat treatment on the characteristic of...
Nitrogen oxides were treated by a positive streamer corona in both, multi-wire-to-plane and wire-to-plane discharge reactors. In the former reactor, the target was to establish a uniform streamer corona. It was successfully generated using a DC power supply and NO/N 2 500-ppm initial gas, when a series gap was set into the circuit, which enhanced the treatment up to 7.5g NO/kW h. In the wire-plane...
Current interrupting capability and distribution of the airflow velocity were investigated in a flat-type air-blast arc quenching chamber. Seven orifice-nozzles with different inlet widths were used to obtain various distributions of the flow velocities. A number of interruption tests for an AC current with a peak value of 1000 A revealed that a decrease in the inlet width from 20 to 10mm markedly...
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