Energy resolving the atomic hydrogen outflux created within plasmas by charge exchange (CX) of hot plasma ions with cooler hydrogen neutrals is used to infer the ion energy distribution within the plasma, IEDp. In high- β plasma with field nulls and ion gyro-radii comparable to the plasma size, the measured ion energy distribution (IEDm) of the CX outflux will depend on the viewing angle and position of the detector. Here, we describe the physics for this, results from a synthetic diagnostic code that contrasts the IEDm to the IEDp within relatively small and hot field-reversed-configuration plasmas, and how these data can show the presence of magnetic nulls and different orbit classes in the plasma.