Journal of Theoretical and Applied Physics (JTAP) Comparison between plasma distribution in plane and concave cathodes DC discharge systems Volume 18 (2024) Special Issue-AICIS’23 2024 07 26 Comparison between plasma distribution in plane and concave cathodes DC discharge systems 10.57647/j.jtap.2024.si-AICIS23.19 EN Mohammed O. Salman Department of Medical Physics, College of Applied Science, University of Fallujah, Iraq Wasan Abd Al-Rahman Khalaf Ministry of Education, Iraq Barakat O. Ahmed Ministry of Education, Anbar Educational Directorate, Anbar, Iraq Journal Article 2024 07 26 in the realm of design optimization. This study employs the finite element method (FEM) through COMSOLMultiphysics software (Version 4.0) to simulate direct current discharge plasma within argon gas under vacuum (2×10−1 mbar). The primary objective is to compare the plasma distribution characteristics resulting from two distinct cathode configurations: a planar cathode, and a concave cathode. The findings of this investigation demonstrate a noteworthy disparity in the distribution of plasma between the two cathode designs. The substitution of the planar cathode with the concave variant leads to a considerable confinement of the plasma within a more delimited spatial region, specifically at a particular point within the system. Moreover, notable variations are observed in the spatial distribution of critical parameters such as electron temperature, electron density, and positive ions density. Furthermore, the spatial distribution of the space charge is markedly dissimilar in the configuration featuring the concave cathode. It is inferred that the plasma zone experiences a unique spatial arrangement in this scenario, with the plasma being confined predominantly in close proximity to the z-axis, but encompassing a larger circular region at 1.5 cm away from the cathode.