Ultrafast electron diffraction (UED) is a growing accelerator application that enables the study of transient material processes at sub-picosecond timescales with nanometer spatial resolution. In this proceeding, we present simulations of the Cryogenic Brightness-Optimized Radiofrequency Gun (CYBORG) beamline using the General Particle Tracer (GPT) code that are optimized for the application of UED. We explore advantages of performing UED with a beamline equipped with a low intrinsic emittance photocathode, extraction fields approaching 200 MV/m, and a cathode temperature below 77 K. The electron beam bunch length and the 4D transverse emittance are critical metrics for achieving high spatial and temporal resolution in UED, and are minimized at the sample location in our optimization using a Non-Dominated Sorting Genetic Algorithm II (NSGA II).

Future electron accelerator applications such as x-ray free electron lasers and ultrafast electron diffraction are dependent on significantly increasing beam brightness. We have designed and produced a new CrYogenic Brightness-Optimized Radiofrequency Gun (CYBORG) for use in a new beamline at UCLA to study the brightness improvements achievable in this novel low temperature high gradient accelerating environment. We are currently in the process of commissioning the photogun for operation with peak cathode fields in excess of 120 MV/m. We report here on the status of conditioning the photogun and report on dark current measurements and maximum field achieved thus far.

The newly commissioned CYBORG (CrYogenic Brightness Optimized Radiofrequency Gun) beamline at UCLA operates in a high gradient, low temperature regime inaccessible to most other existing photoguns and cathode testing infrastructure. The beamline is designed to study electron emission in regime. The final intended configuration of the beamline will be used for studies of novel photocathodes including low mean transverse energy (MTE), high quantum efficiency (QE) semiconductor cathodes dependent on future laser improvement. In the near term, the unique environment allows us to study temperature dependent effects on dark current. Notable reduction in dark current at cryogenic temperatures was observed, a behavior not predicted by Fowler-Nordheim type field emission. Initial results are presented.

Future electron accelerator applications such as x-ray free electron lasers and ultrafast electron diffraction are dependent on significantly increasing beam brightness. We have designed and produced a new CrYogenic Brightness-Optimized Radiofrequency Gun (CYBORG) for use in a new beamline at UCLA to study the brightness improvements achievable in this novel low temperature high gradient accelerating environment. We are currently in the process of commissioning the photogun for operation with peak cathode fields in excess of 120 MV/m. We report here on the status of conditioning the photogun and report on dark current measurements and maximum field achieved thus far.

High field radio frequency (RF) accelerating structures are an essential component of modern linear accelerators (linacs) with applications in photon production and ultrafast electron diffraction. Most advanced designs favor compact, high shunt impedance structures in order to minimize the size and cost of the machines as well as the power consumption. However, breakdown phenomena constitute an intrinsic limitation to high field operation which ultimately affects the performance of a given structure requiring dedicated tests. The introduction of a recent design based on cryogenic distributed coupling structures working at C-band (~6 GHz) allows to increase the shunt impedance by use of alternative distribution schemes for the RF power while mitigating the breakdowns thanks to the low temperature. In this paper we introduce the plan for high field and breakdown tests envisioned for a simple two-cell version of the aforementioned structure. Moreover, we discuss the joining procedure utilized to unify the two fabricated halves of such a structure and relying on the diffusion bonding technique which constitutes an attractive alternative to the brazing approach.

In Mithra Laboratory at UCLA, we are commissioning an S-band Hybrid gun which has a photocathode RF gun and a traveling-wave velocity buncher section contained in one integrated structure. To analyze its performance, we have measured the beam energy at various launch phases and the cavity temperatures. The beam charge was observed up to 200 pC, and emittance and bunch length measurements are now underway. We will report the detailed results of this experimental campaign, and plans for the near future.

Ultrafast electron diffraction (UED) is a growing accelerator application that enables the study of transient material processes at sub-picosecond timescales with nanometer spatial resolution. In this proceeding, we present simulations of the Cryogenic Brightness-Optimized Radiofrequency Gun (CYBORG) beamline using the General Particle Tracer (GPT) code that are optimized for the application of UED. We explore advantages of performing UED with a beamline equipped with a low intrinsic emittance photocathode, extraction fields approaching 200 MV/m, and a cathode temperature below 77 K. The electron beam bunch length and the 4D transverse emittance are critical metrics for achieving high spatial and temporal resolution in UED, and are minimized at the sample location in our optimization using a Non-Dominated Sorting Genetic Algorithm II (NSGA II).

At Los Alamos National Laboratory (LANL), we developed a 1.6-cell C-band RF photoinjector for the Cathodes And Radiofrequency Interactions in Extremes (CARIE) project. The injector will be used to study the behavior of advanced photocathode materials under very high RF gradients. The photocathodes will be prepared with an INFN-style photocathode plug, compatible with the plugs used by other institutions. This presentation will report the RF design of the photoinjector with distributed coupling and RF field symmetrization. Beam physics simulations show that symmetrized RF fields in the vicinity of the beam axis are essential for minimizing the normalized emittances for a 250-pC electron bunch. We will also present the design for the photocathode insertion and the analysis of the challenges related to reducing the peak electric fields, multipactor suppression, and resonant frequency tuning by fine adjustment of the plug position.

This study focuses on developing beam-matching optics for the transport of the MITHRA beam into plasma to study long range plasma effects. To ensure successful injection into the plasma chamber, matching conditions are crucial at the entrance. A dedicated focusing system, comprising beam-matching optics, is designed to transport the beam from the 1.5-meter linear accelerator (linac) and align the necessary parameters at the plasma entrance. Optimization simulations employing Elegant and General Particle Tracer (GPT) codes, based on MITHRA gun data, have been conducted with promising results that align with our expectations. Further investigations involve simulating the PWFA interaction using advanced, fully relativistic, three-dimensional Particle-in-Cell (PIC) codes, namely OSIRIS and QuickPIC.