Transient Chaos of Plasma Ions Near a Magnetic Dipole Field*

The kinetic theory of plasma waves is often studied by using analytic methods, particle simulations, or a hybrid solution. While some analytic methods are robust enough to include perturbative nonlinear terms in the system’s Hamiltonian, a general kinetic theory for an arbitrary zero-order magnetic field does not exist. Here, the phase space of plasma ions in a background dipole magnetic field is investigated by numerical experiment. Global analysis methods of dynamical systems are employed, and the scattered ion orbits are shown to exhibit transient chaos. The trapped [1] and unbounded [2] orbits of charged particles in a dipole field have been investigated previously; here we further classify the system as a chaotic scattering problem and attempt to predict kinetic plasma effects that may manifest. The unperturbed phase space is also augmented to include collisions and a perturbing electric field. Results are compared to previously studied problems of chaotic scattering in magnetized space plasmas [3].

[1] Dragt, Alex J., and John M. Finn. "Insolubility of trapped particle motion in a magnetic dipole field." Journal of Geophysical Research 81, no. 13 (1976): 2327-2340.

[2] Jung, Christof, and H-J. Scholz. "Chaotic scattering off the magnetic dipole." Journal of Physics A: Mathematical and General 21, no. 10 (1988): 2301.

[3] Chen, James. "Nonlinear dynamics of charged particles in the magnetotail." Journal of Geophysical Research: Space Physics 97, no. A10 (1992): 15011-15050.