The details of trajectories of charged particles become increasinglyimportant for proper understanding of processes of formation of radiation instrong and curved magnetic fields. Because of damping of the perpendicularcomponent of motion, the particle's pitch angle could be decreased by manyorders of magnitude leading to the change of the radiation regime -- fromsynchrotron to the curvature mode. To explore the character of this transition,we solve numerically the equations of motion of a test particle in a dipolemagnetic field, and calculate the energy spectrum of magnetic bremsstrahlungself-consistently, i.e. without a priori assumptions on the radiation regime.In this way we can trace the transitions between the synchrotron and curvatureregimes, as well as study the third (intermediate or the so-calledsynchro-curvature) regime. We briefly discuss three interesting astrophysicalscenarios, the radiation of electrons in the pulsar magnetosphere in the polarcap and outer gap models, as well as the radiation of ultrahigh energy protonsin the magnetosphere of a massive black hole, and demonstrate that in thesemodels the synchrotron, synchro-curvature and curvature regimes can be realizedwith quite different relative contributions to the total emission.
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