Particle fluxes and gross erosion at limiters in JET low-confinement mode plasmas measured with visible cameras

Deuterium (D) and beryllium (Be) fluxes are obtained in JET Low-confinement mode (L-mode) plasmas at the outer limiters of the first wall using calibrated visible cameras. They are inferred from the measured radiances using the spectroscopic S/XB method. From the fluxes, the effective gross erosion yield Y^eff of the limiter surface is estimated. After discussing the uncertainties in the proposed methodology, we show the dependence of the deduced particle fluxes and Y^eff of recent JET L-mode plasmas on: separatrix-limiter clearance, magnetic field and plasma current, neutral beam injection and ion cyclotron resonance heating power, average plasma density and majority ion mass, hydrogen (H), deuterium (D) and tritium (T). The results are in general accord with prior edge plasma L-mode understanding. Finally, the obtained Y^eff yields are discussed in view of updated SDTrim surface-particle interaction code calculations. The possible contribution of parasitic light due to reflections from the divertor is examined.