Dartmouth Events

Abstract: Thermal ion sensors are a useful tool for measuring in-situ auroral plasma parameters. This thesis looks at data from a low-resource retarding potential analyzer (RPA) built at Dartmouth in order to prove the capability of these sensors. The RPAs collect a sigmoidal current-voltage curve which depends on a non-linear combination of plasma parameters, so a least-squares minimization algorithm [Roberts, 2017] is run to fit the the best choice plasma parameters for each I-V curve. Data from RPAs onboard the ISINGLASS sounding rocket are fit to find ion temperature, ion density and spacecraft sheath potential over the course of the flight. Then two sequential I-V curves from one sensor are used to extract the plasma flow components, a data product that usually relies on high-resource instruments that measure the electric field. ISINGLASS also ejected four small sub-payloads with onboard RPAs to collect simultaneous, multipoint measurements. Spatial features of an auroral arc are determined by looking at each spacecraft's response to Alfvénic activity at the exit of the arc. These cases represent the versatility of these low-resource sensors and are used to recommend future flight configurations to optimize in-situ data collected on future sounding rocket missions.