In future fusion devices, the particle transport towards the PFC is crucial. Large particle flows lead to faster degradation of the materials, resulting in large maintenance expense and therefore, uneconomical power plants. So-called blob-filaments, which are intermittently released density perturbations at the plasma edge, transport plasma particles through the SOL towards the wall. A deeper understanding of the generation and propagation of these blob-filaments is required to ensure low particle fluxes on the PFC. At the ASDEX Upgrade tokamak, the plasma edge ne is well probed by a LIB diagnostic. The diagnostic is based on the interaction of a neutral LIB and the plasma particles. The emitted Li I(2p - 2s) line radiation is depending on ne. In the frame of this thesis, the sensitivity of the LIB diagnostic is investigated by numerical simulation of artificial ne perturbations on background ne profiles. The corresponding line radiation profiles are calculated and analysed. The essential result is that in the SOL the perturbations are well resolvable in amplitude and size, giving the LIB diagnostic the ability to measure velocities and sizes of blob-filaments. Furthermore, the relation between the ne perturbation amplitude (or size) and the line radiation perturbation amplitude (or size) is almost linear. Statistical data analysis methods as conditional averaging and cross correlation analysis are applied to the artificial and measured line radiation profiles to determine blob-filament sizes. Owing to the lifetime of the Li(2p)state, the line radiation profiles are smeared. Using a Richardson-Lucy algorithm, this smearing can be deconvolved, enabling the direct determination of radial positions and sizes of blob-filaments from conditionally averaged line radiation profiles. A series of plasma discharges, varying the magnetic field B, is performed to investigate the relation between the most stable blob-filament size delta_* and B. Surprisingly, the blob-filament sizes, which are determined by cross correlation analysis, are about a factor of three larger, than the sizes delta_* predicted from theory. The B ^-4/5 dependence of delta_* from the theoretical blob model is not reproduced by the measurements.