Plasma wave probe
Listed on a station in astrometrics
A plasma wave probe was a type of probe used by Starfleet to study plasma waves.
Aboard USS Voyager, a subspace communication station in astrometrics listed information on plasma wave probes alongside solar wind dispersion, cometary ions, prestellar nebulae, interstellar matter and nucleosynthesis. (VOY: "Ashes to Ashes", okudagram)