RF Breakdown

This program addresses significant scientific issues attending RF breakdown and pulsed heating phenomenon as they arise in high-gradient warm accelerator structures, and maximize acceleration gradients in these metallic structures without increasing the RF breakdown probability.

In this program, microwave cavities will be designed and tested that support the superposition of the fundamental TM010 mode and at least one more mode whose eigenfrequency is a harmonic of the TM010 eigenfrequency, either TM020 or TM011, as the nearest TM modes to TM010. These cavities will be vehicles to deepen understanding of RF breakdown and pulsed heating, and as possible candidates for incorporation into multi-cavity high-gradient accelerator structures.

Using our novel multi-frequency RF source, synchronized multi-harmonic cavity modes can be selectively excited in a precisely-controlled manner. In this way, unconventional spatial-temporal distributions of electromagnetic fields within a cavity can be realized, with the potential to lower field emission and/or pulsed heating at a given level of acceleration gradient, since these phenomena are believed to be precursors to RF breakdown.