Rocket‐borne measurements of electron temperature and density with the Electron Retarding Potential Analyzer instrument

Abstract

Determining electron temperature in the ionosphere is a fundamentally important measurement for space science. Obtaining measurements of electron temperatures at high altitudes (>700 km) is difficult because of limitations on ground‐based radar and classic spacecraft instrumentation. In light of these limitations, the rocket‐borne Electron Retarding Potential Analyzer (ERPA) was developed to allow for accurate in situ measurement of ionospheric electron temperature with a simple and low‐resource instrument. The compact ERPA, a traditional retarding potential analyzer with multiple baffle collimators, allows for a straightforward calculation of electron temperature. Since its first mission in 2004, it has amassed significant flight heritage and obtained data used in multiple studies investigating a myriad of phenomena related to magnetosphere‐ionosphere coupling. In addition to highlighting the scientific contributions of the ERPA instrument, this paper outlines its theory and operation, the methodology used to obtain electron temperature measurements, and a comparative study suggesting that the ERPA can also provide electron density measurements.

Review of in-space plasma diagnostics for studying the Earth’s ionosphere

“…Their device consisted of four nickel mesh screens and a series of concentric brass collimators. Their RPA was used at altitudes between 100 km and 700 km; in 2016 the same sensor was used to measure electron temperature and density at >700 km altitude [47], showing good correspondence with previously reported data, and demonstrating that an RPA can be used to characterize the ionosphere at heights well beyond the thermosphere.…”

Numerical simulations of a sounding rocket in ionospheric plasma: Effects of magnetic field on the wake formation and rocket potential

“…An accurate knowledge about the floating potential of spacecraft is crucial for plasma measurements, especially when the floating potential is comparable to the energy of the measured ambient plasma particles [ Olsen et al , ; Cohen et al , ]. Equally important are the effects of the charged spacecraft, and its sheath, on the trajectories of plasma particles, which can be used to determine the plasma temperature [ Comfort et al , ; Fernandes and Lynch , ].…”

Spatiotemporal Limitations of Data‐Driven Modeling: An ISINGLASS Case Study

“…The main payload of ISINGLASS B included the energetic electron instrument Acute Precipitating Electron Spectrometer (APES) (Michell et al., 2016), the COrnell Wire BOom Yo‐yo System (COWBOYS) electric field instrument (Klatt et al., 2005), a retarding potential analyzer sensor Petite Ion Probe (PIP) (Fisher et al., 2016; Fraunberger et al., 2020), and a thermal electron plasma sensor Electron Retarding Potential Analyzer (ERPA) (Cohen et al., 2016; Frederick‐Frost et al., 2007). Multi‐point measurements were also made using PIPs carried by 4 sub‐payloads, known as BOBs (Roberts, Lynch, Clayton, Disbrow, et al., 2017, Roberts, Lynch, Clayton, Weiss, et al., 2017), ejected from the main payload.…”