An improved sheath impedance model for the Van Allen Probes EFW instrument: Effects of the spin axis antenna

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F17%3A00476047" target="_blank" >RIV/68378289:_____/17:00476047 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1002/2016JA023597" target="_blank" >http://dx.doi.org/10.1002/2016JA023597</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1002/2016JA023597" target="_blank" >10.1002/2016JA023597</a>

Jazyk výsledku

angličtina

Název v původním jazyce

An improved sheath impedance model for the Van Allen Probes EFW instrument: Effects of the spin axis antenna

Popis výsledku v původním jazyce

A technique to quantitatively determine the sheath impedance of the Van Allen Probes Electric Field and Waves (EFW) instrument is presented. This is achieved, for whistler mode waves, through a comparison between the total electric field wave power spectra calculated from magnetic field observations and cold plasma theory and the total electric field wave power measured by the EFW spherical double probes instrument. In a previous study, a simple density-dependent sheath impedance model was developed in order to account for the differences between the observed and calculated wave electric field. The current study builds on this previous work by investigating the remaining discrepancies, identifying their cause, and developing an improved sheath impedance correction. Analysis reveals that anomalous gains are caused by the spin axis antennas measuring too much electric field at specific densities and frequencies. This is accounted for in an improved sheath impedance model by introducing a density-dependent function describing the relative effective length of the probe separation, Leff, in addition to the sheath capacitance and resistance values previously calculated. Leff values vary between between 0.5 and 1.2, with values >1 accounting for the anomalous gains and values <1 accounting for the shorting effect at low densities. Applying this improved sheath impedance model results in a significant increase in the agreement level between observed and calculated electric field power spectra and wave powers over the previous model.

Název v anglickém jazyce

An improved sheath impedance model for the Van Allen Probes EFW instrument: Effects of the spin axis antenna

Popis výsledku anglicky

A technique to quantitatively determine the sheath impedance of the Van Allen Probes Electric Field and Waves (EFW) instrument is presented. This is achieved, for whistler mode waves, through a comparison between the total electric field wave power spectra calculated from magnetic field observations and cold plasma theory and the total electric field wave power measured by the EFW spherical double probes instrument. In a previous study, a simple density-dependent sheath impedance model was developed in order to account for the differences between the observed and calculated wave electric field. The current study builds on this previous work by investigating the remaining discrepancies, identifying their cause, and developing an improved sheath impedance correction. Analysis reveals that anomalous gains are caused by the spin axis antennas measuring too much electric field at specific densities and frequencies. This is accounted for in an improved sheath impedance model by introducing a density-dependent function describing the relative effective length of the probe separation, Leff, in addition to the sheath capacitance and resistance values previously calculated. Leff values vary between between 0.5 and 1.2, with values >1 accounting for the anomalous gains and values <1 accounting for the shorting effect at low densities. Applying this improved sheath impedance model results in a significant increase in the agreement level between observed and calculated electric field power spectra and wave powers over the previous model.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

<a href="/cs/project/LH15304" target="_blank" >LH15304: Umístění analyzátoru elektromagnetických vln ELMAVAN na umělé družice projektu Resonance, zpracování a interpretace získaných dat</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Geophysical Research: Space Physics

ISSN

2169-9380

e-ISSN

—

Svazek periodika

122

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

10

Strana od-do

4420-4429

Kód UT WoS článku

000401340800038

EID výsledku v databázi Scopus

2-s2.0-85017619056