Collisionless Particle Dynamics in Diamagnetic Trap

Collisionless motion of particles is studied in axisymmetric mirror machine in the regime in which the pressure of confined plasma is equal to the magnetic field pressure in the trap (the diamagnetic confinement regime). Due to the low magnetic field in the central region, nonconservation of the magnetic moment can result in the chaotic motion and collisionless loss of particles escaping from the trap. The confinement of particles can be ensured either due to the adiabatic invariant conservation (if the magnetic field changes slowly in the longitudinal direction), or due to the fast azimuthal rotation (the so-called absolute confinement). The criteria for the particle confinement are obtained and the lifetime of chaotically moving particles is estimated. The plasma confinement time in the diamagnetic trap has been also estimated in the regime of gas-dynamic outflow.