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. The laser source is a 5 J Q-switched Nd:YAG laser. Without a spectral channel at the laser wavelength, only dust particles that emit broadband light could be detected; these particles have been observed on JET after disruptions. The timing of their emission is clearly different from that expected for a Thomson scattering pulse. The light pulse from dust happens after the peak of the laser light and has a long tail.