- 18 -


      Neutrons gained by "scattering in" =
    dVf d     f v    ,Nrvr           *,,n ]n
 VN  N dN    v  n f  '  N  f N 'N t)Gs(, vv, JVN          dv'         n n



The general Boltzmann equation for neutrons in a fissioning plasma can now be written as


      Tn(r, n,~,t) + v n   Vn(rv n n t)

        + J dV N f d NN(',VN' N't)rt(v)n(rvn n't)V'n

  SX(v) dVN  d    dv I d  V(vf)N rVM


  +   ~   N df N~ nv f nN ,NNta(rV 'Vt
                   x n( ~ n n t~v'n
          Nr NJnnnn
   + d  f d Nf dvI d I N(r, VN1 N't)as(-r ,v' v, n' 4 V v n)n

                   x n(r,v n, n t~v'   (2.3)


Equation (2.3) shows the means by which the relative velocity enters into the individual collision processes. This form of the Boltzmann equation is still quite general. As such, it does not immediately suggest obvious methods of reduction to simpler forms which are more amenable to