This work presents the design of a compact high-efficiency terahertz source, a collaborative effort between UCLA and RadiaBeam Technologies. The system, driven by a thermionic RF gun, features prebunching elements including alpha-magnet and electromagnetic chicane to effectively compress the long beam generated from the gun. By sending such beam into tapering enhanced waveguide oscillator, we can achieve high efficiency energy extraction in different regimes. This work focuses on the beam dynamics in the beamline prior injection into the undulator. A brief mention of the simulation results for radiation generation is also presented.

Ultrafast Electron Diffraction (UED) is a pioneering method for real-time observation of atomic-level structures. Recent advancements leverage relativistic electrons from radiofrequency (RF) guns to overcome space charge limitations, enhancing resolution. While perspectives may differ, an ongoing debate surrounds the optimal energy for a UED instrument. Our study contributes to this discussion by employing an 8.2 MeV electron beam and a compact post-sample magnetic optical system with small-gap Halbach permanent magnet quadrupoles. This system allows tunable magnification and improved reciprocal space resolution in a compact footprint, as demonstrated in simulations and experiments with a single crystal Au sample.