High power RF generation by relativistic beams in dielectric structures and its application to the advanced accelerators

We have studied the interaction of a high current relativistic electron beam with dielectric loaded waveguides as a source of high power electromagnetic radiation. A unique high current photoinjector-based electron linac was used to generate the drive beam for these experiments. Travelling wave dielectric structures with luminal (v(phase) = c) frequencies of 7.8, 15 and 20 GHz were used. The rf power levels generated in these experiments were very large- up to 4 - 20 MW. This class of RF sources has been used for two beam acceleration studies for future linear collider research. With the newly improved RF photoinjector at the Argonne National Laboratory (ANL), we expect to generate up to 0.5 GW RF power in the range of 20 - 60 GHz with a pulse length of tens ns. With this soon to be available RF power source, we could test acceleration structures up to gradients of 1 GV/m.