  An unprecedented increase of kinetic energy of laser accelerated heavy ions
is demonstrated. Ultra thin gold foils have been irradiated by an ultra short
laser pulse at an intensity of $6\times 10^{19}$ W/cm$^{2}$. Highly charged
gold ions with kinetic energies up to $> 200$ MeV and a bandwidth limited
energy distribution have been reached by using $1.3$ Joule laser energy on
target. $1$D and $2$D Particle in Cell simulations show how a spatial
dependence on the ions ionization leads to an enhancement of the accelerating
electrical field. Our theoretical model considers a varying charge density
along the target normal and is capable of explaining the energy boost of highly
charged ions, leading to a higher efficiency in laser acceleration of heavy
ions.
