  Beam-driven collinear wakefield accelerators (CWAs) that operate by using
slow-wave structures or plasmas hold great promise toward reducing the size of
contemporary accelerators. Sustainable acceleration of charged particles to
high energies in the CWA relies on using field-generating relativistic electron
bunches with a highly asymmetric peak current profile and a large energy chirp.
A new approach to obtaining such bunches has been proposed and illustrated with
the accelerator design supported by particle tracking simulations. It has been
shown that the required particle distribution in the longitudinal phase space
can be obtained without collimators, giving CWAs an opportunity for employment
in applications requiring a high repetition rate of operation.
