  The design, construction and performance characteristics of a simple
axial-field ionization chamber suitable for identifying ions in a radioactive
beam are presented. Optimized for use with low-energy radioactive beams (< 5
MeV/A) the detector presents only three 0.5 $\mu$m/cm$^2$ foils to the beam in
addition to the detector gas. A fast charge sensitive amplifier (CSA)
integrated into the detector design is also described. Coupling this fast CSA
to the axial field ionization chamber produces an output pulse with a risetime
of 60-70 ns and a fall time of 100 ns, making the detector capable of
sustaining a relatively high rate. Tests with an $\alpha$ source establish the
detector energy resolution as $\sim$8 $\%$ for an energy deposit of $\sim$3.5
MeV. The energy resolution with beams of 2.5 and 4.0 MeV/A $^{39}$K ions and
the dependence of the energy resolution on beam intensity is measured. At an
instantaneous rate of 3 x 10$^5$ ions/s the energy resolution has degraded to
14% with a pileup of 12%. The good energy resolution of this detector at rates
up to 3 x 10$^5$ ions/s makes it an effective tool in the characterization of
low-energy radioactive beams.
