Analysis and modelling of gamma ray emission in large tokamak plasmasŽohar, Andrej (Avtor) Lengar, Igor (Mentor) Nocente, Massimo (Komentor) tokamakJETplasma transportreaction cross-sectionplasma gamma ray spectrumMonte Carlo particle transportgamma ray sourceTRANSPMCNPvariance reductionADVANTGUnderstanding the physics of fast ions in a fusion plasma is widely regarded as one of the crucial tasks for the reliable operation of fusion tokamak reactors. Measurements on tokamaks have shown that gamma rays are produced when fast ions react either with the plasma fuel ions or with main plasma impurities such as beryllium, carbon, oxygen and nitrogen. Spectroscopy of these gamma rays can be used to measure fusion rates in the plasma or to determine the behaviour and confinement of fusion reaction products, such as alpha particles. The dissertation focuses on the development of a modelling methodology for the creation of a realistic plasma gamma ray source for Monte Carlo transport simulations in large tokamaks. The methodology consists of several steps. First step is the generation of validated plasma parameters using the code TRANSP based on experimental measurements. Second step is the generation of sampling distribution functions from the calculated plasma parameters, such as the calculation of the source position distribution function based on the reaction rate densities for the gamma ray emitting reaction. Third step is the creation of a realistic plasma gamma ray source for the code MCNP to simulate gamma ray transport. The validation of the developed methodology is performed using gamma ray spectra measured with the tangential gamma ray spectrometer during two JET three-ion radio frequency heating scenario discharges performed in the JET 2019 Deuterium experimental campaign. For validation, the calculated plasma gamma ray spectrum was combined with the neutron induced prompt gamma ray background originating in the vacuum vessel and scaled to absolute values by calculating the total number of plasma gamma ray and neutron emitting reactions. The comparison shows good agreement between the shape and absolute values of the spectra at the end of a long detector line of sight. An analysis of a deuterium-tritium neutron commissioning discharge is also performed to test and prepare the developed methodology for the deuterium-tritium experimental campaign at JET. Validation and testing of the developed methodology for the plasma gamma ray source at JET provides a basis for using the developed methodology to support the development of future tokamaks such as ITER and DEMO.20222022-06-11 08:15:04Doktorsko delo/naloga137336VisID: 123103COBISS_ID: 111284227sl