Spectra probabilities for electron beams normally impigning a magnetic helical slab

Abstract We consider a region where there is a magnetic field rotatesuniformly around the z-axis maintaining a perpendicular orientation to it. This region is traversed along the mentioned axis by beams of charge carriers of a given energy. We analytically calculate the band structure of the charge carriers parametrized by the intensity and spatial period of the helical field. We demonstrate the existence of three band gaps two of them partial and one total whose widths depend on the system parameters. For small fields the three band gaps are separated by propagation intervals, but after a critical value they merge.