  Plastic deformation of microsamples is characterised by large intermittent
strain bursts caused by dislocation avalanches. Here we investigate how ion
irradiation affects this phenomenon during single slip single crystal
plasticity. To this end, in situ compression of Zn micropillars oriented for
basal slip was carried out in a SEM. The unique experimental setup also allowed
the concurrent recording of the acoustic emission (AE) signals emitted from the
sample during deformation. It was shown that irradiation introduced a
homogeneous distribution of basal dislocation loops that lead to hardening of
the sample as well as strain softening due to dislocation channeling at larger
strains. With the used deformation protocol strain burst sizes were found to be
decreased due to channeling. The concurrently recorded AE events were
correlated with the strain bursts and their analysis provided additional
information of the details of collective dislocation dynamics. It was found
that the rate of AE events decreased significantly upon irradiation, however,
other statistical properties did not change. This was attributed to the
appearance of a new type of plastic events dominated by short-range
dislocation-obstacle interactions that cannot be detected by AE sensors.
