Error Field Analysis of Joint TEXT Tokamak

This paper presents the study and analysis of the error field of Joint TEXT tokamak. Error fields are first calculated through both the finite-element method and the theoretical method. Then, a Fourier decomposition of the error field is performed on the plasma surface to evaluate the lower mode (m, n) = (1, 1), (2, 1), and (3, 1) error fields. The results of the two methods are notably consistent. Superposition and linearity are also verified for small misalignments. The major sources of error fields are discussed by comparing the error fields caused by different misalignments of various coils. A Monte Carlo simulation, which combines the contribution of all the coils, is performed to obtain the total error fields. A comparison between the calculated and measured error fields is also conducted. The results indicate that the analysis method presented in this paper is very effective in predicting the error field.