Experimentation and Modeling of Self-Organization in Cathode Boundary Layer Discharge in Noble Gas

Niraula, Prajwal

Peacock Scholarship

Experimentation and Modeling of Self-Organization in Cathode Boundary Layer Discharge in Noble Gas

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Self organized pattern formation (or self organization) of microplasma in Cathode Boundary Layer Discharge is a phenomenon first seen in high purity Xenon (Xe) gas by research group led by Schoenbach at Old Dominion University [1]. Attempts by same research group to obtain similar results in other noble gases such as Krypton and Argon had failed. However, simulations performed by Pedro et. al. using COMSOL® suggested possibility of self-organization in Krypton as well as other noble gases at higher pressure [2]. Many competing models for the process of self organization were proposed [12] . At our laboratory, we have focused particularly in understanding the phenomenon of self-organization by gathering more data. Data were typically gathered by planar reactor structure in the pressure range between 50 Torr and 200 Torr, and such the results were used to evaluate the different competing models. In doing so, our experimental finding have verified some of the claims made in simulation by Pedro et. al. This includes the reporting of missing mode: the ring structure, which had not been previously observed, and the modes of structures leading up to ring structure [9]. Besides, self-organization was observed in Krypton and was found to be equivalent to the ones seen in Xenon [2] as suggested by the model. While Molybdenum was primarily used as the cathode material, cathode materials such as Aluminum, Hafnium, Tungsten, Silver, Steel, Nickel, Titanium, Zinc and Copper were also tested. In addition, different reactor design, dielectric material, anode material and hole design were studied. In characterizing the plasma, the electrical properties of plasma were studied which included Current Voltage Curve (CVC), and Current Density Voltage Curve (CDVC). Additionally, optical emission spectrum of plasma were taken and studied carefully.

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