Power deposition and thermal response of PLTs rotatable limiter

Two-dimensional temperature contours of the Princeton Large Torus (PLT) rotatable limiter have been measured using a calibrated infrared camera with ≅ 30 ms time resolution. These experiments were performed during intense ion cyclotron range of frequencies (ICRF) heating (1.0-5.0 MW) and lower hybrid current drive (LHCD) (P > 500 kW at 800 MHz or 2.45 GHz). Different expressions of energy deposition from the scrape-off region (λ = 0.05 cm to 2.00 cm) are used to compare to the thermal contours on the limiter's front surface. One model of the scrape-off region assumes a simple exponential decay of particles and is derived from the intersection of a toroid and an infinite plane. A second model, derived from the diffusive motion of individual particle trajectories, has a near gaussian particle flux profile. The effects of Debye length and gyromotion are also modeled. Temperature predictions generated by a three-dimensional finite difference thermal model of the limiter have the following inputs: A temporal and spatial variation of power on the limiter's surfaces, nonlinear temperature-dependent material properties, surface radiation to the vacuum vessel walls and surface sublimation effects. The contour maps of the limiter's front surface are generated from the thermal model's temperature predictions for cases with and without limiter rotation. (orig.)