What's Wrong with Space Plasma Metrology?

Storey, L. R. O.

doi:10.1029/gm102p0017

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…In order to train and validate inference models as those from m-NLP, it is necessary to have data sets with low level (L1B in satellite data parlance) currents and associated plasma and satellite parameters (n e , T e , V f ). Ideally such a data set should be constructed from actual accurate measurements, crossvalidated with different instruments, but this is rarely possible in practice, owing to challenges in making such measurement in space or lab plasma [13,[40][41][42]]. An alternative is to use synthetic data sets using analytic models [2,7], or computer simulations [31,33], from which precise values of collected currents and corresponding plasma parameters are known.…”

Section: Methodsmentioning

confidence: 99%

Inference of plasma parameters from fixed-bias multi-needle Langmuir probes (m-NLP)

Guthrie

Marchand

Marholm

2021

Meas. Sci. Technol.

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New approaches are presented to infer plasma densities and satellite floating potentials from currents collected with fixed-bias multi-needle Langmuir probes (m-NLP). Using synthetic data obtained from kinetic simulations, comparisons are made with inference techniques developed in previous studies and, in each case, model skills are assessed by comparing their predictions with known values in the synthetic data set. The new approaches presented rely on a combination of an approximate analytic scaling law for the current collected as a function of bias voltage, and multivariate regression. Radial basis function regression (RBF) is also applied to Jacobsen et al's procedure (2010 Meas. Sci. Technol. 21 085902) to infer plasma density, and shown to improve its accuracy. The direct use of RBF to infer plasma density is found to provide the best accuracy, while a combination of analytic scaling laws with RBF is found to give the best predictions of a satellite floating potential. In addition, a proof-of-concept experimental study has been conducted using m-NLP data, collected from the Visions-2 sounding rocket mission, to infer electron densities through a direct application of RBF. It is shown that RBF is not only a viable option to infer electron densities, but has the potential to provide results that are more accurate than current methods, providing a path towards the further use of regression-based techniques to infer space plasma parameters.

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Section: Methodsmentioning

confidence: 99%

Inference of plasma parameters from fixed-bias multi-needle Langmuir probes (m-NLP)

Guthrie

Marchand

Marholm

2021

Meas. Sci. Technol.

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“…The methodology and results of the investigation for the Swarm EFI, with a focus on the TII, are described in the "Theoretical TII measurement performance" section. Our study may be seen to address, if in part, the titular problem raised by Storey (1998): "What's wrong with space plasma metrology? "…”

Section: Introductionmentioning

confidence: 98%

Swarm Thermal Ion Imager measurement performance

Burchill

Knudsen

2022

Earth Planets Space

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We assess the performance of the thermal ion imaging (TII) technique as conceived for the Swarm Earth Explorer satellites. Analysis, simulation, and laboratory testing performed prior to flight provided estimates of systematic and random error sources of the electric field instrument’s vector ion drift, electric field, and ion kinetic temperature measurements. An end-to-end instrument simulator, consisting of models of the TIIs on a prototypical Swarm satellite orbiting Earth with ionospheric plasma, electric field, and magnetic field inputs, was used to generate TII sensor data (level 0 instrument data). These data were processed with a prototype processor (the level 1b processor) to characterize theoretical measurement performance. We describe the methodology used to assess TII measurement uncertainty and present the main findings of the end-to-end measurement performance study. In addition, we assess the measurement performance achieved during approximately eight years of orbital operations. Example measurements demonstrate the quality of ion drift velocity. Unprocessed TII imagery reveals spurious signals which can affect measurement performance. Availability of such imagery has proven vital for diagnosing measurement anomalies associated with sensor operation and spacecraft–plasma interactions. Graphical Abstract

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