“Magnetic mirror" is the term for the region of the magnetic field in which there is an intense concentration of lines of induction (Fig. 28.19a). Suppose a charged particle approaches a magnetic mirror, as shown in the figure. What will happen to it?

Explanation

As was shown above (see Problem 28.5), the particle will move along a helix winding around the lines of induction. Let us resolve

the velocity vector into two components: the lateral `v_(bot)` (the orbital velocity) and the longitudinal (the drift velocity). Since the orbital moment of the circulating charge is directed against llice field, the magnetic forces Lend to push the charge oul into the region of the weak field (compare with 37.4 and 4.10, where the dipole and Taxele moments are arranged it direction of the field). We see that as the charge approaches the magnetic mirror, its drift velocity decreases, becoming zero in the case of a sufficientiy high field gradient (fig. 28.19h). From this moment it begins to drilt in the opposite direction towards the weaker field (Fig. 28. 19c).