Thermography of target plates with near-infrared optical fibres at Tore Supra

First spectroscopic near-infrared thermography measurements in the range 0. 9-1.95 mum performed with optical fibres are reported. Two set-ups served a s test-beds for physical and technical questions for a security system base d on fibre optical thermography. It was found that for the interesting temp erature range above 600 degreesC atomic and molecular line emission is negl igible in comparison with thermal radiation. The observed near-infrared spe ctra are however different from simple blackbody radiation curves. They are explained by the coverage of the surface with dust and flakes. The dust pa rticles are identified by their spectral emissivity falling off with the sq uare of the wavelength. On one set-up, flakes were identifiable by fast coo l-down times and confirmed by post-experiment inspection. In the absence of flakes, surface temperatures on a ripple protection plate were measured, t hat allowed to determine the mean energy of ripple trapped ions to be 200-3 00 keV. (C) 2001 Elsevier Science B.V. All rights reserved.