On the charged particle motion in magnetic and electric fields in case of heavy non-uniformity of the magnetic field

Charged particle motion in mutually perpendicular electric and magnetic fields is considered. It is suggested that the magnetic field is plane-parallel, depends on one coordinate and changes considerably at distances of the order of the Larmor radius. The electric field is considered constant and weak. Adiabatic invariant has been found, motion properties have been shown and comparison with the known case of motion in a slowly changing magnetic field has been carried out. It is shown that the intense change of the field can not result in intense (by an order) change of particle energy as compared with motion in the slowly changing field, i.e., in the case considered ''superadiabatic'' particle acceleration is impossible