Modelling potential fluctuations due to filaments in the SOL

Abstract

The filtered Poisson process are often used in analysing the fluctuations in the scrape-off layer. This thesis investigates how the FPP-model represents both the ion saturation current, Jsat and the velocity signals. The signals are simulated using blobmodel [1], with different degree of overlap, for K = 103, K = 104 and K = 105, different amplitudes, set to constant or exponentially distributed, and different distributions of the position in y-direction, degenerated or uniform. The results show that for the Jsat signal, the FPP-model fits well, which also was expected. The results for Jsat also showed that varying the distribution for the positions in y-direction, did not affect the results of the model. So for Jsat, the FPP-model is a good model for analysing. When analysing the velocity signals, there were more different results. Some of the results show no good analysis of the different signals, but especially for the velocity with exponentially distributed amplitudes, the analysis show also some good results and estimated values. Therefor, the conclusion is that the Jsat signal is well represented in the single-point measurement analysis. The velocity signals can also be analysed using the same technique, but does also require some other adaptions, for example include negative values in the analysis.