Developing Fixed-Bias Langmuir Probes for Multi-Point Constellation Deployments

Since their initial development in the early 20th century, electrostatic Langmuir probes have proved invaluable in terrestrial and interplanetary ionospheric sounding applications. When deployed aboard rocket and satellite platforms, these probes yield high-cadence, in-situ measurements of key plasma parameters such as electron density, ion density, and electron temperature. Furthermore, the efficacy of Langmuir probes in characterizing the three-dimensional structure and dynamics of ionospheric plasmas can be augmented by the technique of multi-payload deployments. In this work, we discuss the design, development, and analysis of fixed-bias Langmuir probes constructed for two multi-point science campaigns: the Mars-bound, dual-satellite Escape and Plasma Acceleration and Dynamics Explorers (ESCAPADE) mission and the Sporadic E ElectroDynamics Demonstration (SpEED Demon) sounding rocket (launched on August 24, 2022). We begin with a basic treatment of the relevant background material, including ionosphere fundamentals and Langmuir probe theory. Next, we discuss the development process of the ESCAPADE Langmuir Probe (ELP) suite, highlighting the motivating design principles, instrument hardware, and pre-flight calibration. The process of radiation tolerance assurance for the ELP is considered in further detail; however, as the ESCAPADE satellites have yet to take flight, we follow this discussion with a presentation of data from the SpEED Demon deployable subpayloads, noting potential mechanisms for the density structures and irregularities which were observed during flight. Finally, we conclude with a brief summary and discussion of future work.