  Laser-driven ions have compelling properties and their potential use for
medical applications has attracted a huge global interest. One of the major
challenges of these applications is generating beams of the required energies.
To date, there has been no systematic study of the effect of laser intensity on
the generation of laser-driven ions from ultrathin foils during relativistic
transparency. Here we present a scaling for ion energies with respect to the
on-target laser intensity and in considering target thickness we find an
optimum thickness closely related to the experimentally observed relativistic
transparency. A steep linear scaling with the normalized laser amplitude a0 has
been measured and verified with PIC simulations. In contrast to TNSA, this
scaling is much steeper and has been measured for ions with Z > 1. Following
our results, ion energies exceeding 100MeV/amu are already accessible with
currently available laser systems enabling realization of numerous advanced
applications
