  Terahertz (THz)-based electron manipulation has recently been shown to hold
tremendous promise as a technology for manipulating and driving the
next-generation of compact ultrafast electron sources. Here, we demonstrate an
ultrafast electron diffractometer with THz-driven pulse compression. The
electron bunches from a conventional DC gun are compressed by a factor of 10
and reach a duration of ~180 fs (FWHM) with 10,000 electrons/pulse at a 1 kHz
repetition rate. The resulting ultrafast electron source is used in a
proof-of-principle experiment to probe the photoinduced dynamics of
single-crystal silicon. The THz-compressed electron beams produce high-quality
diffraction patterns and enable observation of the ultrafast structural
dynamics with improved time resolution. These results validate the maturity of
THz-driven ultrafast electron sources for use in precision applications.
