A new method to analyze density fluctuation by microwave reflectometry

The runaway phase phenomenon is a problem in reflectometry measurements. The change in the phase difference between the reflected wave and the reference one cannot be explained by the movement of the cut-off layer when the runaway phase phenomenon occurs. It is difficult to extract information of the density fluctuation from the data with the runaway phase. We show a model in which the runaway phase phenomenon comes from the wave scattered by the density fluctuations, and describe a new analysis method based on this model. The obtained results on plasma displacement and density fluctuation spectrum are presented.