  Equation of state measurements at Jovian or stellar conditions are currently
conducted by dynamic shock compression driven by multi-kilojoule multi-beam
nanosecond-duration lasers. These experiments require precise design of the
target and specific tailoring of the spatial and temporal laser profiles to
reach the highest pressures. At the same time, the studies are limited by the
low repetition rate of the lasers. Here, we show that by the irradiation of a
thin wire with single beam Joule-class short-pulse laser, a converging
cylindrical shock is generated compressing the wire material to conditions
relevant for the above applications. The shockwave was observed using Phase
Contrast Imaging employing a hard X-ray Free Electron Laser with unprecedented
temporal and spatial sensitivity. The data collected for Cu wires is in
agreement with hydrodynamic simulations of an ablative shock launched by a
highly-impulsive and transient resistive heating of the wire surface. The
subsequent cylindrical shockwave travels towards the wire axis and is predicted
to reach a compression factor of 9 and pressures above 800 Mbar. Simulations
for astrophysical relevant materials underline the potential of this
compression technique as a new tool for high energy density studies at high
repetition rates.
