Suppose that a particle (d, t or electron) at z = 0 in this cylindrical symmetric plasma confinement configuration has perpendicular and parallel energy components, mv^o2 /2 and mv zo2 /2, respectively. Suppose that mv zo2 /2 is big enough that this particle can reach the z position where the axial magnetic field is 2 B 0 without being reflected. Show that the ratio of the particle's gyroradius at z = 0, r go , to its gyroradius, r g1 , where the B-field is 2 B0 is (2)1/2