Effect of a gravitational field on the motion and radiation of relativistic particles in a magnetic field and in the electric field parallel to it
Gurevich L.E., Dynkin S.D.
It is shown that the increase in the energy of charged particles in a strong gravitational field and in parallel magnetic and electric fields can be limited, that in special relativity their energy cannot increase simultaneously with the transverse component of the velocity, and that the maximum magnetic bremsstrahlung can change its direction with time.