Füzyon tabanlı tokamak reaktörlerinde plazma duvar etkileşimi ve malzeme güvenilirliğinin teorik ve deneysel olarak incelenmesi

Fusion reactions involve the nuclei of deuterium (D) and tritium (T), transforming into nuclei of helium (He). However, the repulsion force that exists between two positively charged nuclei obstruct their ability to combine. A collision between two nuclei would require them to be propelled toward each another at exceedingly high velocities resulting in elevated temperatures. The amalgamation of these two atoms at an approximate temperature of 100 million degrees Celsius is required. Plasma is produced when D and T atoms are ionized at this temperature. For the nuclei to merge, the plasma must remain warm. Tokamak reactors are specifically designed for this purpose. The geometry Tokamak is designed to ensure the confinement of the plasma within the magnetic field. The dissipation of impact-induced heat is hindered. To commence and maintain the reaction, it is imperative that the plasma density and temperature must reach a specific threshold. Approximately 4 kiloelectron volts (keV) of energy is necessary to achieve an initial temperature of about 45 million degrees Celsius. The plasma's movement at high speeds within a magnetic field, generates an electric current, which in turn, creates a secondary magnetic field. The presence of this magnetic field induces irregularities or turbulence in the plasma, causing certain ions to break up and become free from the magnetic field. So that the escaped ions collide with the reactor wall. During the reaction process, the positive and negative ions that escape from the magnetic field environment interact with the walls of the Tokamak, resulting in deformation. As a consequence, the plasma wall gradually degrades, leading to the emission of neutrons into the surrounding environment. The interaction between plasma and the wall is a critical issue that causes distribution in the fusion process in Tokamak reactors. Graphite, Beryllium, Aluminum, and Tungsten are the most resilient materials against ion abrasion in the plasma wall as stated in the literature. vi In this thesis we investigate the interaction between plasma and wall materials both theoretically and experimentally. The theoretical part of the thesis is concentrated on investigating the physical and chemical erosion of different wall materials (graphite, aluminum, and tungsten) employed in the fusion reactor due to plasma interaction. This degradation is a result of plasma interactions. The Monte Carlo approach is utilized to examine these erosion effects. In addition, the study examines the effects of these erosion on the durability and longevity of the reactor's wall material. This study also aims to examine the physical and chemical changes that occur when a plasma of helium ions, created by applying a high direct current (DC) voltage in a vacuum, interacts with an aluminum surface. The interaction of the samples with the plasma, the cracks caused by physical erosion, and the deformations caused by sputtering were determined by employing atomic force microscopy and electron microscopy for structural characterization. The reliability of the material samples is assessed by utilizing the Weibull method to calculate the mean depth of the pits formed on the material's surface as a result of deformations.