Non-axisymmetric evolutionary equilibrium plasma models in presence of three-dimensional conducting structures

Nuclear nuclei to form a heavier atomic nucleus, with the release of a large fusion is a process that involves the combination of two atomic amount of energy. This process happens at the heart of stars, and represents the potentially future main source of energy for the mankind. One of the main challenges in the development of a nuclear fusion reactor is the confinement of plasma. Magnetic confinement is one of the most promising methods for this purpose, and is based on the use of magnetic fields to confine plasma in a toroidal chamber. Tokamaks are machines that represent nowadays the main approach to the development of a nuclear fusion reactor. In a Tokamak, the plasma is confined by means of a magnetic field generated by a set of coils and the plasma itself. One of the main problems associated with Tokamaks are the disruptions phenomena, events in which the plasma suddenly loses stability and collapses. Disruptions can cause serious damage to the structure, and their control (or mitigation) represents one of the main challenges to be overcome for the development of a safe and efficient nuclear fusion reactor. The magnetic forces acting on the device vessel during a disruption are of great importance for the estimation of the damage sustained by the structure. However, direct measurement of these forces is difficult and complicated. In this PhD thesis, the study and implementation of a model to calculate the total net magnetic forces acting on the vessel during a disruption, from information obtained only by magnetic diagnostics, is proposed. The model is implemented in a numerical code that allows the calculation of the forces on the COMPASS Tokamak device, although the proposed approach is general and can be applied to other devices, and their comparison with the forces evaluated with CarMa0NL, an advanced and well-established code. The method has been also applied using experimental data collected from the COMPASS shots database, and the results will be discussed. The thesis is organized as follows: • Chapter 1: Controlled thermonuclear fusion. In this chapter, an highlight on the nuclear fusion, the main plasma models, and the most important fusion devices will be given. • Chapter 2: Tokamaks. In this chapter an insight on the Tokamaks devices will be given. • Chapter 3: Equilibrium codes. This chapter contains an overview of the equilibrium codes necessary to the model here presented, along with an additional tool. • Chapter 4: Force calculation. This chapter is focused on the description of the model and details about its numerical implementation. • Chapter 5: Model validation. In this chapter, a parametric analysis on the numerical implementation of the model will be shown, along with first results obtained from the comparison with the CarMa0NL tool. • Chapter 6: Results. In this chapter some applications on simulations and real diagnostics data will be shown. • Conclusions.