Impurity transport measurements in the PISCES-A linear plasma device

The parallel transport, in terms of diffusion and advection by entrainment in parallel plasma flow, of impurities relevant to proposed ITER divertor materials (W, C) are studied in a linear He plasma. Introduction of the impurities in controlled amounts is accomplished by blow-off of thin films using a (1064nm, 75 mJ) pulsed Nd:Yag laser. Neutral and ion excited state emission are measured with an optically filtered PMT array. Emission profiles are compared to a 1.5 D advection plus diffusion numerical model to obtain a parallel flow speed and parallel and perpendicular diffusion coefficients. This work also expands on earlier results [1] by including multiple downstream measurement locations to quantify impurity acceleration and the controlled spot size of impurity blow-off. \\[4pt] [1] E. M. Hollmann et. al., J. Nucl. Mater (2010) in press