SLAC, Menlo Park, California, USA
Michigan State University, East Lansing, Michigan, USA
Planar polycrystalline synthetic diamond with nitrogen-doping/incorporation was found to be a remarkable field emitter. It is capable of generating a high charge beam and handling moderate vacuum conditions. Integrating it with an efficient RF cavity could therefore provide a compact electron source for RF injectors. Understanding the performance metrics of the emitter in RF fields is essential toward developing such a device. We investigated a test setup of the field emitter at the X-band frequency. The setup included an X-band cavity operating at the TM02 mode. The field emitter material will be plated on the tip of a insertion rod on the cavity back plate. Part of the back plate and the emitter rod are demountable, allowing for exchange of the field emitters. The TM02 mode was chosen such that the design of the demountable back plate does not induce field enhancement at the installation gap. The cavity were optimized to achieve a high surface field at the emitter tip and a maximum energy gain of the emitted electrons at a given input power. We will present the RF and mechanical design of such a TM02 X-band cavity for field emitter testing.
UCLA, Los Angeles, California, USA
Michigan State University, East Lansing, Michigan, USA
Northern Illinois University, DeKalb, Illinois, USA
SLAC, Menlo Park, California, USA
The dielectric wakefield acceleration (DWA) program at FACET produced a multitude of new physics results that range from GeV/m acceleration to the discovery of high field-induced conductivity in THz waves, and beyond, to a demonstration of positron-driven wakes. Here we review the rich program now developing in the DWA experiments at FACET-II. With increases in beam quality, a key feature of this program is extended interaction lengths, near 0.5 m, permitting GeV-class acceleration. Detailed physics studies in this context include beam breakup and its control through the exploitation of DWA structure symmetry. The next step in understanding DWA limits requires the exploration of new materials with low loss tangent, large bandgap, and improved thermal characteristics. Advanced structures with photonic features for mode confinement and exclusion of the field from the dielectric, as well as quasi-optical handling of coherent Cerenkov signals is discussed. Use of DWA for laser-based injection and advanced temporal diagnostics is examined.
Michigan State University, East Lansing, Michigan, USA
LANL, Los Alamos, New Mexico, USA
MSU, East Lansing, Michigan, USA
As the next generation of accelerator technology pushes towards being able to achieve higher and higher gradients there is a need to develop high-frequency structures that can support these fields *. The conditioning process of the structures and waveguides to high gradient is a labor-intensive process, its length increases as the maximum gradient is increased. This results in the need to automate the conditioning process. This automation must allow for high accuracy calculations of the breakdown probabilities associated with the conditioning process which can be used to instruct the conditioning procedure without the need for human intervention. To automate the conditioning process at LANL’s high gradient C-band accelerator test stand we developed FEbreak that is a breakout probability and conditioning automation software that is a part of the FEmaster series **, ***, ****. FEbreak directly interfaces with the rest of FEmaster to automate the data collection and data processing to not only analyze the breakdown probability but also the dark current effects associated with these high gradient structures.
* E. I. Simakov Nuc. Inst. and Meth, in Phy. Research Section A: Acc. Spec, 907 221 (2019)
** E. Jevarjian arXiv:2009.13046
*** T. Y. Posos arXiv:2012.03578
**** M. Schneider arXiv:2012.10804