  An Electromagnetic (EM) pulse falling on a plasma medium from vacuum can
either reflect or propagate inside the plasma depending on whether it is
overdense or underdense. In a magnetised plasma, however, there are usually
several pass and stop bands for the EM wave depending on the orientation of the
magnetic field with respect to the propagation direction. The EM wave while
propagating in a plasma can excite electrostatic disturbances in the plasma [1,
2]. In this work Particle - In - Cell simulations have been carried out to
illustrate the complete transparency of the EM wave propagation inside a
strongly magnetised plasma. The external magnetic field is chosen to be
perpendicular to both the wave propagation direction and the electric field of
the EM wave, which is the X mode configuration. Despite the presence of charged
electron and ion species the plasma medium behaves like a vacuum. The
observation is understood with the help of particle drifts. It is shown that
though the two particle species move under the influence of EM fields their
motion does not lead to any charge or current source to alter the dispersion
relation of the EM wave propagating in the medium. Furthermore, it is also
shown that the stop band for EM wave in this regime shrinks to a zero width as
both the resonance and cut-off points approach each other. Thus transparency to
the EM radiation in such a strongly magnetised case appears to be a norm. This
may have important implications in astrophysical scenarios. For instance, the
plasma surrounding objects like pulsars and magnetars is often threaded with
strong magnetic fields.
