This study reports the performance of single crystal chemical vapor deposit diamond detectors for measuring space plasma and energetic particles: ~7keV energy resolution for protons with a 14keV threshold level, and good response linearity for ions and electrons as expected from Monte-Carlo calculations of primary particle energy loss. We investigated that these diamond detectors are able to operate at high temperature (>70°C) and have fast response times (<1ns rise time). While silicon detectors have proven capability over this energy range for space plasma measurements, diamond detectors offer a faster response, higher temperature operation, greater radiation tolerance, and immunity to light.