Detection of dust on JET with the high resolution Thomson scattering system.

Dust particles have been observed with Thomson scattering systems on several tokamaks. We present here the first evidence of dust particles observed by the new high resolution Thomson scattering system on JET. The system consists of filter spectrometers that analyze the Thomson scattering spectrum from 670 to 1050 nm in four spectral channels.

Mutual interaction of Faraday rotation and Cotton–Mouton phase shift in JET polarimetric measurements.

The paper presents a study of Faraday rotation (FR) angle and Cotton–Mouton (CM) phase shift measurements to determine their mutual interaction and the validity of the linear models presently used in equilibrium codes. Comparison between time traces of measurements and model calculations leads to the result that only an exact numerical solution of Stokes equations can reproduce in all the experimental data. As a consequence, approximated linear models can be applied only in a limited range of plasma parameters.

A new calibration code for the JET polarimeter.

An equivalent model of JET polarimeter is presented, which overcomes the drawbacks of previous versions of the fitting procedures used to provide calibrated results. First of all the signal processing electronics has been simulated, to confirm that it is still working within the original specifications. Then the effective optical path of both the vertical and lateral chords has been implemented to produce the calibration curves.

Thomson-scattering diagnostic on the Frascati tokamak upgrade.

The Frascati tokamak upgrade Thomson-scattering system is used for the measurement of electron-temperature and electron-density spatial profiles along the vertical diameter of the tokamak at 19 spatial points up to 10 times in a single plasma discharge, with a spatial resolution that ranges from 2 cm in the central region to 4 cm in the plasma edge. The radiation source is a Nd:YLF laser that operates at 1053 nm, with a divergence of 0.4 mrad full angle, and is capable of delivering a burst of 10 pulses with energies of 4.