Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
A two dimensional wave propagation code, developed specifically to simulate X-mode correlation reflectometer measurements in the ITB of JT-60U plasmas is described. The code makes use of separate computational methods in the vacuum, underdense and reflection regions of the plasma in order to obtain the high computational efficiency and robust solution necessary for correlation analysis. The simulations are applied to the interpretation of density fluctuation levels and radial correlation lengths measured in the ITB of reverse shear plasmas in JT-60U. Experimentally, a dramatic reduction of the radial correlation length is observed from \approx 20 cm in the core of the plasma before ITB formation to \approx 4mm in the fully developed ITB. Throughout the formation of the ITB the coherent reflection is maintained. Simulation of X-mode reflectometry in these plasmas reveals that the inferred correlation length in the ITB is close to the instrumental resolution of the diagnostic, setting a lower limit on the radial wavenumber and fluctuation level which can be inferred.