Application of the time-space finite element method to the thermomechanical analysis of the first wall

The time-space finite element method has been applied to one-dimensional non-steady heat conduction problems. By theoretical analyses based on the condition number of the relevant coefficient matrix, the time-space method has been found to be much more precise and stable than the Crank-Nicolson method. This has also been confirmed by several numerical analyses including the thermal problems of the first wall. As an application of the time-space finite element heat conduction analysis, the thermal ratchetting of the first wall has been analysed. By comparing the numerical results with the provisions of the ASME Code Case N-47, it has been found that N-47 cannot be applied to the thermal ratchetting of the first wall subjected to repeated plasma disruption. (orig.)