Tables 5.1 and 11.1 gives estimates for the values of the various parameters that characterize our rescaled reduced neoclassical driftMHD model, (11.68)–(11.72), in a lowfield
and a highfield tokamak fusion reactor. (See Chapter 1.) These estimates are made using the following assumptions:
(lowfield) or
(highfield),
,
,
(where and are the deuteron and triton masses, respectively),
, , , (where is the minor radius of the plasma), , , ,
, and
.
Table 11.1:
Parameters characterizing the rescaled reduced neoclassical driftMHD equations for a lowfield and a highfield
tokamak reactor. [See Equations (11.6), (11.74), (11.75), and (11.80)–(11.82).]

LowField 
HighField 

5.0 
12.0 

0.565 
0.565 
















Let us adopt the orderings

(11.92) 
where
. As is clear from Tables 5.1 and 11.1, these orderings are reasonable provided that the radial width of the
magnetic island chain that develops in the inner region exceeds a few centimeters.
Let us
also adopt the orderings

(11.93) 
As is clear from Tables 5.1 and 11.1, the ordering is consistent with the orderings (11.92). Unfortunately, the
orderings
are not consistent with the orderings (11.92). (It would actually be more consistent to
adopt the orderings
.) Nevertheless, we are forced to adopt the orderings
in order to make further progress. (By adopting
these ordering we are essentially ensuring that the bootstrap current and curvature terms in our analysis are not so large that they lead to a breakdown of the
constant approximation.)
Finally, suppose that


(11.94) 
and let us expand the various fields in our rescaled model as follows:
Here,
,
, et cetera are assumed to be
in the inner region.