Ion wind thrusters (IWTs) present a promising propulsion technology for high-altitude platforms. However, accurate methods for testing IWT performance in high altitude flight conditions are lacking. Wind tunnel experiments are essential in the context of evaluating IWTs, but significant challenges exist due to the absence of suitable measurement technologies for low density conditions. Particle image velocimetry (PIV) is a promising method for assessing the flow field around IWTs, yet it has not been applied in combination with a low density flow. The critical issue here is the identification of suitable tracer particles. This paper addresses this gap by advancing the application of PIV in low-density atmospheres, with a comprehensive tracer particle study as its core contribution, laying the groundwork for future wind tunnel experiments. Beside the low pressure conditions, the influence of the corona discharge on the tracer particles is analyzed. Multiple collector surface materials are investigated regarding the influence of their reflective properties on PIV measurements.