Dielectric structures driven by laser-generated terahertz (THz) pulses may
hold the key to overcoming the technological limitations of conventional
particle accelerators and with recent experimental demonstrations of
acceleration, compression and streaking of low-energy (sub-100 keV) electron
beams, operation at relativistic beam energies is now essential to realize the
full potential of THz-driven structures. We present the first THz-driven linear
acceleration of relativistic 35 MeV electron bunches, exploiting the collinear
excitation of a dielectric-lined waveguide driven by the longitudinal electric
field component of polarization-tailored, narrowband THz pulses. Our results
pave the way to unprecedented control over relativistic electron beams,
providing bunch compression for ultrafast electron diffraction, energy
manipulation for bunch diagnostics, and ultimately delivering high-field
gradients for compact THz-driven particle acceleration.Comment: 8 pages, 4 figure
