The scrape-off layer code EDGE2D has been extended to accommodate more
than one impurity species [1]. The parallel transport coefficients ar
e calculated from a 21 moment description using the method of reduced
charge states (RCS). Simulations with carbon and helium as impurities
have been carried out to validate the multi-species version of EDGE2D.
It is shown that further use of RCS allows the reduction of the numbe
r of momentum equations. The computing time is thereby substantially r
educed. At the same time the code results show little difference betwe
en using the reduced set of momentum equations and using the full set.