Radiation from Cerenkov Wakes in a Magnetized Plasma

The Cerenkov wake excited by a particle beam or a short laser pulse in a perpendicularly magnetized plasma is analyzed. The wake couples to electromagnetic radiation of approximate frequency ${\omega }_p$ at the plasma/vacuum boundary. The radiation amplitude is ${\omega }_c/{\omega }_p$ times the amplitude of the wake excited in the plasma (for a sharp boundary). Particle-in-cell simulations verify the scaling laws. Since plasma wakes as high as a few GeV/m are produced in current experiments, the potential for a high-power (i.e., GW) coherent microwave to THz radiation source exists.