Electron density profile reconstruction from multichannel microwave interferometer data at W7-AS

A multichannel microwave interferometer has been built for the W7-AS fusion experiment in order to study temporal phenomena in plasma density. For this reason, electron density profile reconstruction methods based on regularization functionals were studied. Simulations showed, that the minimum Fisher-information approach (adapted from tomography) gives better results than the maximum entropy approach. This is due to the fact, that in the minimum Fisher-information method the reconstructed distribution is inherently assumed to be continuous, whereas the maximum entropy method the distribution is assumed to be noncontinuous. The profiles reconstructed from multichannel interferometer data are in good agreement with the profiles measured by other diagnostic systems.