Samples of modern plastic track detectors of the CR-39, PM-355, and PM-600 types were exposed to hydrogen and helium ion beams of relatively low energy (70–250 keV), which were provided by an accelerator. In order to determine low energy detection limits of the detectors a track diameter evolution was investigated as a function of particle energy and etching time. Other samples of the detectors were irradiated with helium ions of energy 0.5, 1.0 and 2.0 MeV. After that the irradiated samples were heated up to 200°C and etched to investigate influence of these temperatures on track parameters.