ONE-DIMENSIONAL AND 2-DIMENSIONAL SIMULATIONS OF ULTRA-SHORT-PULSE REFLECTOMETRY

Ultra-short-pulse reflectometry is studied by means of the numerical i ntegration of one- and two-dimensional full-wave equations for ordinar y and extraordinary modes propagating in a plasma. The numerical calcu lations illustrate the use of the reflection of ultra-short-pulse micr owaves as an effective probe of the density or magnetic profile in the presence of density or magnetic fluctuations in the plasma. Bragg res onance effects can be identified in the reflected signals, which give information on fluctuations. It is also demonstrated that ultra-short- pulse reflectometry can be used to perform correlation reflectometry m easurements in which correlation lengths for density fluctuations are deduced from the observed cross-correlation function of phase shifts a s a function of frequency. (C) 1997 American Institute of Physics.