Compact THz Accelerators: From Fiction to Reality

The use of THz radiation for electron acceleration and manipulation of electron bunches has progressed over the last decade to a level where practical implementations of THz-powered photoguns, LINACs and a wide range of beam manipulators have become possible. Here, we present a segmented terahertz electron accelerator and manipulator (STEAM) capable of performing multiple high-field operations on the $6\mathbf{D}$ -phase-space of ultrashort electron bunches. With this single device, powered by few-micro-Joule, single-cycle, 0.3 THz pulses, we demonstrate record THz-acceleration of $>\mathrm{30}\mathbf{keV}$ , streaking with $ fs resolution, focusing with $> 2\mathbf{kT}/\mathbf{m}$ strength, compression to $\sim \mathbf {100}$ fs as well as real-time switching between these modes of operation. The STEAM device demonstrates the feasibility of THz-based electron accelerators, manipulators and diagnostic tools enabling science beyond current resolution frontiers with transformative impact.