Plasma Species
The plasma is assumed to consist of three (charged) species; namely, electrons (), majority ions (), and impurity ions
(). The charges of the three species are , , and
, respectively, where
is the magnitude of the electron charge.
Quasineutrality [1] demands that

(A.1) 
where is the species number density. Here, is the fluxsurface label introduced in Section 14.2.
Let

(A.2) 
where

(A.3) 
is the effective ion charge number. (See Section 1.6.) It follows that
Finally, let
Note that
.