TUVIR07
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
UMAN, Manchester, United Kingdom
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
Terahertz (THz) pulses are emerging as unique driving sources for next-generation particle accelerators, offering unprecedented control over the energy-time phase-space of a particle bunch compared with conventional radio-frequency technology. Acceleration, compression and streaking have all been demonstrated with low energy electrons* but operation at relativistic energies remains limited. Here, we report on the first demonstration of phase-velocity matched acceleration of a relativistic electron beam in a THz-driven linear accelerator**, confirmed through frequency-tuning of the THz source. Operating in the highest beam energy (35 MeV) and charge (60 pC) regimes reported to date, we use narrowband THz pulses centered at 0.4 THz to drive collinear THz-electron interaction in a dielectric-lined waveguide. We exploit multi-cycle energy modulation of a chirped 6 ps electron bunch to extract the often-inaccessible longitudinal phase-space distribution, highlighting the potential for THz-driven bunch diagnostics. We also show injection-time-dependent preferential energy gain/loss for 2 ps bunches, demonstrating a route to whole-bunch acceleration of sub-ps relativistic electron beams.
*D. Zhang et al. Nat. Photonics 12, 336 (2018).
**M.T. Hibberd et al. arXiv:1908.04055.
