CXRS Impurity Density Measurement Techniques in C-Mod*

The wide-view CXRS system installed on C-Mod provides measurements of the time-dependent boron density, temperature, and flow velocity profiles. Conventional technique for CXRS measurement of the absolute impurity density requires accurate characterization of the local neutral beam parameters such as energy, density and excitation states. Currently this data is routinely provided by the set of beam extraction, propagation and penetration codes. A new unifying beam code (ALCBEAM) is being developed to provide the local beam parameters at any point in the plasma. As an alternative to the conventional CXRS system, a new integrated CXRS/BES system is designed and will be installed on the Alcator C-Mod tokamak. In this approach, the BES system serves as an alternative, more accurate, means for measuring of the local beam densities. Advantages and disadvantages of the both approaches will be discussed.