Dataset for 'High-Energy Sub-cycle Electron Emission Driven by Spatio-temporally Confined THz Fields'

Tip-based structures offer a pathway to strong-field, optical-driven field emission, holding the potential for generating high-brightness ultrashort electron sources. While direct optical field-driven electron emission and acceleration within the single optical sub-cycle provides a straightforward solution for ultrafast electron generation, achieving precise control over the emission process to generate high-quality electron beams suitable for practical applications remains challenging. Here, we present THz-driven sub-cycle electron field emission in a ridged waveguide cavity, achieving the first practical high-energy femtosecond field emission source. This ridged cavity is engineered to spatially and temporally confine the electric field, effectively minimizing dispersion and suppressing field leakage. Through carrier-envelope phase control of the THz field, we achieve sub-cycle field emission, generating, for the first time, isolated electron bunches with a 940 fs (FWHM) duration. Using dual 24 µJ (2×24 µJ) of THz energy, we achieve a peak field strength of ~ 23 GV/m, accelerating electrons to a record energy of 46 keV with a charge of 2 pC per bunch, thereby enabling single-shot imaging. The high field strength suppresses emittance blow-up due to space-charge effects, ensuring excellent beam quality. The generated electron pulse exhibits high stability. As an initial application, we investigate transient electric field dynamics in real time and space using time-resolved schlieren radiography with this field emission electron source. These proof-of-principle results signify a critical advancement in developing compact, high-performance electron sources for user-oriented applications.