Critical escape velocity for a charged particle moving around a weakly magnetized Schwarzschild black hole

Charged-particle motion in the spacetime of a weakly magnetized static nonrotating black hole is investigated. We study the conditions under which a charged particle originally revolving around the black hole in a circular orbit after being kicked by another particle or photon can escape to infinity. The escape velocity for particles at the innermost stable circular orbits is determined and the properties of particles moving with near-critical velocity are discussed. We show that in a general case such motion is chaotic.