Rocket Measurements of Electron Energy Spectra From Earth's Photoelectron Production Layer

• Published in: Geophysical research letters Vol. 49; no. 17
• Main Authors: Collinson, Glyn A., Glocer, Alex, Chornay, Dennis, Michell, Robert, Pfaff, Rob, Cameron, Tim, Uribe, Paulo, Frahm, Rudy A., Rosnack, Traci L, Pirner, Chris, Gass, Ted, Clemmons, Jim, Barjatya, Aroh, Martin, Steven, Akbari, Hassanali, Debchoudhury, Shantanab, Conway, Rachel, Eparvier, Francis, Zesta, Eftyhia, Paschalidis, Nikolaos
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center Wiley / American Geophysical Union 16.09.2022; John Wiley & Sons, Inc; Wiley
• Subjects: Altitude; Atmosphere; Atmospheric physics; Earth; Earth ionosphere; Electric fields; Electron energy; electron spectrometer; Energy; Energy spectra; Flight; Geosciences (General); GLOW; Instrumentation and Photography; Ionosphere; Line spectra; N2 absorption; Outflow; Photoelectrons; photopeaks; Photoproduction; Physics; Prototypes; sounding rocket; Sounding rockets; Spectra; Sunlight; Upper atmosphere
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL098209

Photoelectrons are crucial to atmospheric physics. They heat the atmosphere, strengthen planetary ambipolar electric fields, and enhance the outflow of ions to space. However, there exist only a handful of measurements of their energy spectrum near the peak of photoproduction. We present calibrated energy spectra of pristine photoelectrons at their source by a prototype Dual Electrostatic Analyzer (DESA) instrument flown on 11 July 2021 aboard the Dynamo-2 sounding rocket (NASA № 36.357). Photopeaks arising from 30.4 nm He-II spectral line were observed throughout the flight above 120 km. DESA also successfully resolved the rarely observed N2 absorption feature. Below 10 eV observations were in good agreement with the GLOW suprathermal electron. Above 10 eV fluxes substantially deviated from the model by as much as an order of magnitude.