  The interaction of ion beams with matter includes the investigation of the
basic principles of ion stopping in heated materials. An unsolved question is
the effect of different, especially higher, ion beam fluences on ion stopping
in solid targets. This is relevant in applications such as in fusion sciences.
To address this question, a Thomson parabola was built for the Neutralized
Drift Compression eXperiment (NDCX-II) for ion energy-loss measurements at
different ion beam fluences. The linear induction accelerator NDCX-II delivers
2 ns short, intense ion pulses, up to several tens of nC/pulse, or
10$^{10}$-10$^{11}$ ions, with a peak kinetic energy of ~1.1 MeV and a minimal
spot size of 2 mm FWHM. For this particular accelerator the energy
determination with conventional beam diagnostics, for example, time of flight
measurements, is imprecise due to the non-trivial longitudinal phase space of
the beam. In contrast, a Thomson parabola is well suited to reliably determine
the beam energy distribution. The Thomson parabola differentiates charged
particles by energy and charge-to-mass ratio, through deflection of charged
particles by electric and magnetic fields. During first proof-of-principle
experiments, we achieved to reproduce the average initial helium beam energy as
predicted by computer simulations with a deviation of only 1.4 %. Successful
energy-loss measurements with 1 {\mu}m thick Silicon Nitride foils show the
suitability of the accelerator for such experiments. The initial ion energy was
determined during a primary measurement without a target, while a second
measurement, incorporating the target, was used to determine the transmitted
energy. The energy-loss was then determined as the difference between the two
energies.
