Mohammad Askari; Nikoo Darestani Farahani; Mehdi Bakhshzad Mahmoudi; Fereydoun Abbasi Davani
Abstract
Metal surface cleaning or etching techniques using reactive plasma are emerging as one of the dry processing techniques for surface contaminants with high bond energy, especially for cleaning and decontamination of nuclear components and equipment. In this study, the plasma reaction due to the discharge ...
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Metal surface cleaning or etching techniques using reactive plasma are emerging as one of the dry processing techniques for surface contaminants with high bond energy, especially for cleaning and decontamination of nuclear components and equipment. In this study, the plasma reaction due to the discharge of a dielectric barrier of a mixture of 95% helium and 5% fluorine with cobalt oxide film (Co3O4) grown on the surface of stainless steel 304 was studied experimentally. Experimental results show that cobalt oxide becomes a powder after plasma irradiation and is easily separated from the surface of the base metal. The optimal plasma generating conditions of the dielectric barrier discharge used in this experimental study were obtained at atmospheric pressure, voltage 4.5 kV, and frequency 25 kHz with an etching rate of 10.875 μmol.min-1. The samples were analyzed before and after plasma irradiation, using Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy and the purification rate was performed using a sequential weighting of the samples with scales 10-4 g accurately obtained. The results show the ability of this method to effectively remove the surface contamination of cobalt from the surface of stainless steel 304.
Ali Adeli Ahmadabadi; Zahra Shahbazi rad; Fereidon Abbasi Davani; Behjat Ghasemi
Abstract
In this research, the effect of ions produced in deuterium plasma on Tungsten (W) and Aluminum (Al) plates has been investigated using a plasma focus device with the specifications of (C=10.4 μF, V=23 kV, E=2.75 kJ). The W samples used because it is one of the key elements in the Tokamak device. Because ...
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In this research, the effect of ions produced in deuterium plasma on Tungsten (W) and Aluminum (Al) plates has been investigated using a plasma focus device with the specifications of (C=10.4 μF, V=23 kV, E=2.75 kJ). The W samples used because it is one of the key elements in the Tokamak device. Because we wanted to put the W samples at the distance from the anode top with maximum plasma produced ions, we should find the optimum place. Due to the high cost of W samples, we used Al samples to find the optimal conditions. The samples were irradiated at 8 cm distance from the anode top with deuterium ions produced by a plasma focus device. The sample analyses were done by the SEM and EDX methods. The sample irradiation by deuterium plasma ions caused a lot of damages and bubble formation on the sample surfaces. The analyses showed the extent of surface damage and the number of ions deposited on the surface. The number of damages on the Al surface was much higher than W. Bubbles were formed on the surface were due to the impact of deuterium ions on the W and Al samples. Also, the deuterium ion energy was measured with a Faraday cup as about 50 keV.
Oveis Hasanpour; Fereydoun Abbasi Davani; Farshad Ghasemi; Mahdi Aghayan; Mohammad Nazari; Shahin Sanaye Hajari
Abstract
Two main insulating gases of SF₆ and N₂/CO₂ mixture are employed to increase voltage capability of electrostatic accelerators. SF₆ offers more insulating capability, but environmental and technical disadvantages of SF₆ makes usage of N₂/CO₂ mixture a desirable option. This paper aims to ...
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Two main insulating gases of SF₆ and N₂/CO₂ mixture are employed to increase voltage capability of electrostatic accelerators. SF₆ offers more insulating capability, but environmental and technical disadvantages of SF₆ makes usage of N₂/CO₂ mixture a desirable option. This paper aims to replace SF₆ with N₂/CO₂ in design of a 500 kV/30 mA parallel-fed voltage multiplier. High-voltage section of the accelerator is a capacitive structure which in combination with rectifying elements, generates the accelerating high-voltage. The structure which is called Voltage Multiplier Capacitive Structure (VMCS) is designed and analyzed in this paper. The first structure is designed to employ SF₆ as insulating gas (VMCS500). Then, the structure is modified to be capable of using N₂/CO₂ as insulating gas with lower breakdown voltage (VMCS500-m). The modified structure requires more complex mechanical manufacturing process, but offers the simplicity of using N₂/CO₂ mixture, the option of using the modified structure with superior SF₆ gas, increasing the output voltage and beam energy. CST EM STUDIO was used for capacitance calculation and electric field analysis. LTSPICE was used for equivalent circuit analysis of the high voltage generating section.