title: The geometric factor of electrostatic plasma analyzers: a case study from the Fast Plasma Investigation for the Magnetospheric Multiscale mission.
abstract: We report our findings comparing the geometric factor (GF) as determined from simulations and laboratory measurements of the new Dual Electron Spectrometer (DES) being developed at NASA Goddard Space Flight Center as part of the Fast Plasma Investigation on NASA's Magnetospheric Multiscale mission. Particle simulations are increasingly playing an essential role in the design and calibration of electrostatic analyzers, facilitating the identification and mitigation of the many sources of systematic error present in laboratory calibration. While equations for laboratory measurement of the GF have been described in the literature, these are not directly applicable to simulation since the two are carried out under substantially different assumptions and conditions, making direct comparison very challenging. Starting from first principles, we derive generalized expressions for the determination of the GF in simulation and laboratory, and discuss how we have estimated errors in both cases. Finally, we apply these equations to the new DES instrument and show that the results agree within errors. Thus we show that the techniques presented here will produce consistent results between laboratory and simulation, and present the first description of the performance of the new DES instrument in the literature.
authors.affiliation: Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20071, USA. glyn.a.collinson@nasa.gov
authors.forename: Glyn A
authors.initials: GA
authors.lastname: Collinson
authors.forename: John C
authors.initials: JC
authors.lastname: Dorelli
authors.forename: Levon A
authors.initials: LA
authors.lastname: Avanov
authors.forename: Gethyn R
authors.initials: GR
authors.lastname: Lewis
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Moore
authors.forename: Craig
authors.initials: C
authors.lastname: Pollock
authors.forename: Dhiren O
authors.initials: DO
authors.lastname: Kataria
authors.forename: Robert
authors.initials: R
authors.lastname: Bedington
authors.forename: Chris S
authors.initials: CS
authors.lastname: Arridge
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Chornay
authors.forename: Ulrik
authors.initials: U
authors.lastname: Gliese
authors.forename: Al
authors.initials: A
authors.lastname: Mariano
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Barrie
authors.forename: Corey
authors.initials: C
authors.lastname: Tucker
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Owen
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Walsh
authors.forename: Mark D
authors.initials: MD
authors.lastname: Shappirio
authors.forename: Mark L
authors.initials: ML
authors.lastname: Adrian