Dielectric Disk Accelerator for High Gradient Short Pulse Two-Beam Wakefield Acceleration

In the last two decades, the theoretical and experimental investigations of dielectric accelerating structures for application to wakefield acceleration have predominantly used a dielectric-lined waveguide, due to its simple geometry (i.e. low fabrication cost). However, in comparison with the prevailing metallic disk-loaded accelerators, the dielectric-lined waveguide suffers from a lower Q-factor and lower shunt impedance. We are developing a new dielectric disk accelerator. The preliminary simulation shows that, even with 5×10−4 of loss tangent dielectric material $(E_{r}=50)$, we can achieve ~200 MΩ/m shunt impedance at 26 GHz traveling wave operation (the beam aperture is kept the same in the comparison), which is 4 times higher than those of the conventional dielectric loaded accelerator. The dielectric disk accelerator can overcome conventional limitations on high gradient, high efficiency dielectric accelerator, leading to a breakthrough in the performance of the two-beam accelerator, one of the most promising technologies in the category of advanced accelerator concepts for high energy physics research applications.