Space experiments with particle accelerators (SEPAC) flew on Spacelab 1 in November and December 1983. SEPAC included an accelerator which emitted electrons into the ionospheric plasma with energies up to 5 keV and currents up to 300 mA. The SEPAC equipment also included an energetic plasma generator, a neutral gas generator, and an extensive array of diagnostics. The diagnostics included plasma wave detectors, an energetic electron analyzer, a photometer, a high sensitivity television camera, a Langmuir probe and a pressure gauge. Twenty‐eight experiments were performed during the mission to investigate beam‐plasma interactions, electron beam dynamics, plasma beam propagation, and vehicle charging. The wave‐particle interactions were monitored by the plasma wave instrumentation, by the energetic electron detector and by the optical detectors. All show evidence of wave‐particle interactions, which will be described in this paper.