Using x‐ray arrays to measure impurity transport in the Alcator‐C tokamak

Using three different x‐ray arrays simultaneously, we have made measurements of the transport of aluminum (Z=13) or silicon (Z=14) injected into MIT’s Alcator tokamak plasma. Each array has ∼2 cm spatial and 15 μs temporal resolution. Since Alcator core temperatures are typically between 1 and 2 keV, fully stripped, H‐ and He‐like ions are the only ionization states of the injected impurity with significant populations for r/a≲0.7. The spectral responses of the arrays have been tailored so that each array has a markedly different response to the x radiations from these three ionization states. Through the use of two of these arrays, time‐resolved density profiles of fully stripped and total injected impurities, and studies of their transport, have been previously reported. Current work and description of the analysis method will be presented.