  Proposals to reach the next generation of laser intensities through Raman or
Brillouin backscattering have centered on optical frequencies. Higher
frequencies are beyond the range of such methods mainly due to the wave damping
that accompanies the higher density plasmas necessary for compressing higher
frequency lasers. However, we find that an external magnetic field transverse
to the direction of laser propagation can reduce the required plasma density.
Using parametric interactions in magnetized plasmas to mediate pulse
compression both reduces the wave damping and alleviates instabilities, thereby
enabling higher frequency or lower intensity pumps to produce pulses at higher
intensity and longer duration. In addition to these theoretical advantages, our
new method, in which strong uniform magnetic fields lessen the need for
high-density uniform plasmas, also lessens key engineering challenges, or at
least exchanges them for different challenges.
