  Using 3D radiation-hydrodynamical simulations, we study the effects of
ionising radiation on the formation of second-generation (SG) stars in Globular
Clusters (GCs) with multiple stellar populations. In particular, we focus on
massive ($10^7 \mathrm{M}_{\odot}$) and young (40-Myr old) GCs. We consider
stellar winds from asymptotic giant branch (AGB) stars, ram pressure, gas
accretion onto the cluster, and photoionisation feedback of binary stars. We
find that the stellar luminosity is strong enough to warm and ionise the
intracluster medium, but it does not lead to a significant gas expulsion. The
cluster can thus retain the ejecta of AGB stars and the accreted pristine gas.
In addition, efficient cooling occurs in the central region of the cluster
within $50 \mathrm{Myr}$ from the formation of first generation stars, leading
to the formation of SG stars. Our results indicate that the inclusion of
photoionisation does not suppress SG formation, but rather delays it by about
$\sim10 \mathrm{Myr}$. The time delay depends on the density of the pristine
gas, so that a denser medium exhibits a shorter delay in star formation.
Moreover, photoionisation leads to a modest decrease in the total SG mass,
compared to a model without it.
