  We consider wakefield generation in plasmas by electromagnetic pulses
propagating perpendicular to a strong magnetic field, in the regime where the
electron cyclotron frequency is equal to or larger than the plasma frequency.
PIC-simulations reveal that for moderate magnetic field strengths previous
results are re-produced, and the wakefield wavenumber spectrum has a clear peak
at the inverse skin depth. However, when the cyclotron frequency is
significantly larger than the plasma frequency, the wakefield spectrum becomes
broad-band, and simultaneously the loss rate of the driving pulse is much
enhanced. A set of equations for the scalar and vector potentials reproducing
these results are derived, using only the assumption of a weakly nonlinear
interaction.
