Oscillator motion dynamics in the field of a slow electromagnet wave

It is shown that the particle motion in a constant magnetic field and slow electromagne c wave field becomes chaotic in case of wave amplitude excess of a definite value. In weak magnetic fields the stochastization of a particle motion is caused by the overlapping effect of cyclotron resonances. In case of rather strong magnetic fields the stochastization of the motion arises at a considerable wave amplitude excess over the predicted by resonance overlapping cryterion