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A sheath impedance model has recently been developed to describe how the variable coupling impedance between the Van Allen Probes instrumentation and the ambient plasma affects both the amplitude and phase of electric field wave measurements. Here, the impact of this sheath correction on measured chorus wave properties, including electric field wave power and the Poynting vector, is directly quantified. It is found that the sheath‐corrected electric field wave power is typically between two and nine times larger than the uncorrected measurement, depending on wave frequency. The sheath correction typically increases the Poynting flux by a factor of ∼2, and causes the polar angle of the Poynting vector to switch hemisphere from parallel to anti‐parallel propagation in ∼2% of cases. The uncorrected data exhibit significant deviations from the theoretically predicted relationship between the wave vector and the Poynting vector whereas this relationship is well‐reproduced with the sheath‐corrected observations. Plain Language Summary: The wave electric field on Van Allen Probes has recently been corrected for sheath impedance effects, which can affect both the amplitude and phase of the measurements. Here, for the first time, we directly quantify the impact of this correction factor on chorus wave measurements of electric field wave power. We also investigate the impact on the Poynting vector direction and magnitude, which is itself determined from electric field observations and magnetic field measurements. It is found that after applying the sheath correction to chorus wave observations, the electric field wave power typically increases by a factor between two and nine, whereas the Poynting flux typically increases by a factor of ∼2. The relationship between the wave vector and the Poynting vector is compared to that expected from cold plasma theory, for both the corrected and uncorrected observations. Significant differences between observations and theory are apparent when using the uncorrected measurements, however the sheath‐corrected observations agree well with the theoretical predictions. Key Points: Sheath‐correction results in increase of electric field chorus wave power by a factor of 2–9, and increase in Poynting flux by factor of ∼2Sheath correction causes the Poynting vector to switch hemispheres, from parallel to anti‐parallel propagation, in only ∼2% of casesTheoretically predicted relationship between wave vector and Poynting vector is well‐reproduced with sheath‐corrected data [ABSTRACT FROM AUTHOR]

Spherical double probe electric field sensors become electrically coupled to magnetospheric plasma during operation, leading to an instrument response that varies with the local plasma environment. Here, a method is developed for determining this variable coupling impedance for each measurement direction by using periods of favorable boom, wave, and magnetic field geometry. Comparing electric field complex amplitudes between 30 Hz and 10 kHz observed along each boom direction to those predicted from simultaneous magnetic field measurements and cold plasma theory allows for the amplitude and phase response of the instrument to be quantified over the full range of plasma densities encountered on‐orbit. A sheath model is developed to describe how the sheath resistance, sheath capacitance, and relative effective length vary as a function of plasma density. An additional empirical correction is also included to describe the phase response along the spin‐axis. The modeled sheath correction is subsequently tested for case studies of burst‐mode data and statistical analyses of survey‐mode data. It is demonstrated that the levels of agreement between observations and theoretical predictions based on Faraday's Law are substantially greater for the sheath corrected data than for uncorrected observations. Comparisons between observations with oppositely directed Poynting vector directions reveals that the sheath correction reconciles a bifurcated distribution in the uncorrected data to a single peak centered on agreement with Faraday's Law. A full sheath corrected EMFISIS L4 survey mode data set has been produced for final archive. Full details of the sheath correction are also provided for manual data correction. Key Points: Variable coupling impedance between the instrument and plasma has been quantified for the electric field measurements on Van Allen ProbesSheath correction is demonstrated to substantially improve agreement between data and theoretical predictions from Faraday's LawSheath‐corrected EMFISIS L4 data set produced for archive. Full details are also provided to facilitate manual data corrections [ABSTRACT FROM AUTHOR]

Magnetic search coils (MSCs) are sensitive to both magnetic and electric fields, but detecting electric fields is unnecessary for magnetic observations of plasma waves. However, it is important to evaluate both sensitivities for different geometries and electrostatic shields to avoid electric field pickup. An equivalent circuit model for the electric field sensitivity of an MSC in a collisionless isotropic cold plasma is developed here using electrical coupling through a sheath capacitance. That sensitivity is defined by a relationship between the MSC impedance and the sheath capacitance. To confirm the validity of the circuit model, the sensitivity to an electric field is measured by imposing an external electric field using charged parallel metallic plates in laboratory experiments. The coupling capacitance between the MSC and charged plates is equivalent to the sheath capacitance in a space plasma. The measured results show good agreement with an approximate expression deduced from the equivalent circuit model. [ABSTRACT FROM PUBLISHER]