  We present an experimental demonstration of the efficient acceleration of
electrons beyond 60 MeV using micro-channel plasma targets. We employed a
high-contrast, 2.5 J, 32 fs short pulse laser interacting with a 5 \mu m inner
diameter, 300 \mu m long micro-channel plasma target. The micro-channel was
aligned to be collinear with the incident laser pulse, confining the majority
of the laser energy within the channel. The measured electron spectrum showed a
large increase of the cut-off energy and slope temperature when compared to
that from a 2 \mu m flat Copper target, with the cutoff energy enhanced by over
2.6 times and the total energy in electrons >5 MeV enhanced by over 10 times.
Three-dimensional particle-in-cell simulations confirm efficient direct laser
acceleration enabled by the novel structure as the dominant acceleration
mechanism for the high energy electrons. The simulations further reveal the
guiding effect of the channel that successfully explains preferential
acceleration on the laser/channel axis observed in experiments. Finally,
systematic simulations provide scalings for the energy and charge of the
electron pulses. Our results show that the micro-channel plasma target is a
promising electron source for applications such as ion acceleration,
Bremsstrahlung X-ray radiation, and THZ generation.
