  A dielectric-loaded linac powered by THz-pulses is one of the key parts of
the "Attosecond X-ray Science: Imaging and Spectroscopy" (AXSIS) project at
DESY, Hamburg. As in conventional accelerators, the AXSIS linac is designed to
have phase velocity equal to the speed of light which, in this case, is
realized by tuning the thickness of the dielectric layer and the radius of the
vacuum channel. Therefore, structure fabrication errors will lead to a change
in the beam dynamics and beam quality. Additionally, errors in the bunch
injection will also affect the acceleration process and can cause beam loss on
the linac wall. This paper numerically investigates the process of electron
beam acceleration in the AXSIS linac, taking into account the aforementioned
errors. Particle tracking simulations were done using the code ECHO, which uses
a low-dispersive algorithm for the field calculation and was specially adapted
for the dielectric-loaded accelerating structures.
