  Context. Recent spacecraft observations in the inner heliosphere have
revealed the presence of local Alfvenic reversals of the magnetic field, while
the field magnitude remains almost constant. They are called magnetic
switchbacks and are very common in the plasma environment close to the Sun
explored by the Parker Solar Probe satellite. Aims. A simple numerical model of
a magnetic field reversal with constant magnitude is used in order to explore
the influence of switchbacks on the propagation of energetic particles, within
a range of energy typical of solar energetic particles. Methods. We model the
reversal as a region of space of adjustable size bounded by two rotational
discontinuities. By means of test particle simulations, beams of mono-energetic
particles can be injected upstream of the switchback with various initial
pitch- and gyro-phase angles. In each simulation, the particle energy may also
be changed. Results. Particle dynamics is highly affected by the ratio between
the particle gyroradius and the size of the switchback, with multiple
pitch-angle scatterings when the particle gyroradius is of the order of the
switchback size. Further, particle motion is extremely sensitive to the initial
conditions implying a transition to chaos; for some parameters of the system, a
large share of particles is reflected backwards upstream as they interact with
the switchback. These results can have a profound impact on the solar energetic
particle transport in the inner heliosphere, thus possible comparisons with
in-situ spacecraft data are discussed.
