## R k Rf aWk R t3 dOR dRR3r R t 2135

and the expression for the flux density of particles will be

Ja(r, R, t )=-|«ol(r, R ua(r )Jn(r, R, t)-^ RT d^r, R,') (2.13.6)

When writing Eq. 2.13.5 and Eq. 2.13.6 we used the relation, connecting the particle density «(r, t) with differential particle density n(r, p, t) in the phase space, n(r,t)= Jp2n{r,p,t)dp .

Selecting the total energy E = c\moc + p j (where mo is the rest mass of a particle) as the variable, one can write Eq. 2.13.1 and Eq. 2.13.2 in the form dt dr,

3 dra dE E

In this case the particle density n(r, t) is determined by the expression n(r, t)= Jn(r,E, t)dE .

and the phase density is related by the expression