Note: Improved spatial resolution of time-of-flight Thomson scattering of fusion devices.

To measure the electron density and temperature of the outer half of the International Thermonuclear Experimental Reactor, it is currently planned to build two conventional Thomson scattering (TS) systems. It was recently shown that given the same new specifications and optimizing the optical design, a Light Detection and Ranging (LIDAR) TS system covering the full chord is feasible, too. In this note, we demonstrate that by deconvolving the data of the individual spectral channels, one can improve the spatial resolution of LIDAR TS to match that of the conventional core plasma system. We demonstrate that the scale length at the edge of an H-mode plasma is determined with reasonable accuracy.

High-resolution Doppler-velocity estimation techniques for processing of coherent heterodyne pulsed lidar data.

On the basis of an analysis of the autocovariance of the complex heterodyne signal, some novel algorithms are derived and are investigated for use in determining, with high spatial resolution, Doppler-velocity coherent-lidar profiles in the case of rectangular and rectangularlike sensing laser pulses. These algorithms generalize other known Doppler-velocity estimators for the more complex case of nonuniform scattering and Doppler-velocity distribution within the pulse length. Algorithm performance and efficiency are studied and are illustrated by computer simulations. It is shown that the Doppler-velocity profiles can be determined with essentially better resolution in comparison with the use of other known estimation approaches, but at the expense of some increase in the number of statistical realizations (number of laser shots) required to reduce the speckle-noise effect. The minimum achievable resolution interval is shown to be much shorter than the pulse length.

Reduction of the pulse spike-cut error in Fourier-deconvolved lidar profiles.

A simple approach is analyzed and applied to the National Oceanic and Atmospheric Administration (NOAA) Doppler lidar data to reduce the error in Fourier-deconvolved lidar profiles that is caused by spike-cut uncertainty in the laser pulse shape, i.e., uncertainty of the type of not well-recorded (cut, missed) pulse spikes. Such a type of uncertainty is intrinsic to the case of TE (TEA) CO(2) laser transmitters. This approach requires only an estimate of the spike area to be known. The result from the analytical estimation of error reduction is in agreement with the results from the NOAA lidar data processing and from computer simulation.