2D surface temperature measurement of plasma facing components with modulated active pyrometry.

In nuclear fusion devices, such as Tore Supra, the plasma facing components (PFC) are in carbon. Such components are exposed to very high heat flux and the surface temperature measurement is mandatory for the safety of the device and also for efficient plasma scenario development. Besides this measurement is essential to evaluate these heat fluxes for a better knowledge of the physics of plasma-wall interaction, it is also required to monitor the fatigue of PFCs.

Modeling of the ITER-like wide-angle infrared thermography view of JET.

Infrared (IR) thermography systems are mandatory to ensure safe plasma operation in fusion devices. However, IR measurements are made much more complicated in metallic environment because of the spurious contributions of the reflected fluxes. This paper presents a full predictive photonic simulation able to assess accurately the surface temperature measurement with classical IR thermography from a given plasma scenario and by taking into account the optical properties of PFCs materials.

Experimental study of the ion critical-gradient length and stiffness level and the impact of rotation in the JET tokamak.

Experiments were carried out in the JET tokamak to determine the critical ion temperature inverse gradient length (R/LTi=R|nablaTi|/Ti) for the onset of ion temperature gradient modes and the stiffness of Ti profiles with respect to deviations from the critical value. Threshold and stiffness have been compared with linear and nonlinear predictions of the gyrokinetic code GS2. Plasmas with higher values of toroidal rotation show a significant increase in R/LTi, which is found to be mainly due to a decrease of the stiffness level.

Particle pinch with fully noninductive lower hybrid current drive in Tore Supra.

Recently, plasmas exceeding 4 min have been obtained with lower hybrid current drive (LHCD) in Tore Supra. These LHCD plasmas extend for over 80 times the resistive current diffusion time with zero loop voltage. Under such unique conditions the neoclassical particle pinch driven by the toroidal electric field vanishes.

Application of the pulsed photothermal effect to fast surface temperature measurements.

It is well known that the accuracy of surface temperature measurements by optical means is limited because of the uncertainties that are associated with the emissivity and the reflected fluxes. The application of the photothermal effect produced by a chopped laser beam for surface temperature measurements has proved to be a valuable tool to avoid the errors that are due to the reflected fluxes. In this paper we show that a pulsed laser may also be used for the same purpose.

Noncontact surface temperature measurement by means of a modulated photothermal effect.

The main problems when measuring surface temperature by means of radiometry (i.e., optical pyrometry) are the unknown emissivity and radiation reflected by the sample.