THOR Electric Field Instrument – EFI

0459694 - ÚFA 2017 DE eng A - Abstrakt
Khotyaintsev, Y. - Bale, S. D. - Bonnell, J. W. - Lindqvist, A. - Phal, Y. - Rothkaehl, H. - Souček, Jan - Vaivads, A. - Åhlen, L.
THOR Electric Field Instrument – EFI.
Geophysical Research Abstracts. Göttingen: European Geosciences Union, 2016. EGU2016-11967. ISSN 1607-7962.
[EGU General Assembly 2016. 17.04.2016-22.04.2016, Vienna]
Institucionální podpora: RVO:68378289
Klíčová slova: THOR * plasma turbulence
Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech
http://meetingorganizer.copernicus.org/EGU2016/EGU2016-11967.pdf

Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence.
The Electric Field Instrument (EFI) will measure the vector electric field from 0 to 200 kHz. EFI consists of two
sets of sensors: Spin-plane Double Probes (EFI-SDP) providing high sensitivity DC electric field in the spacecraft
spin plane (2D), and the High-Frequency Antenna (EFI-HFA) providing 3D electric field at frequencies above
∼1 kHz. EFI-SDP consists of 4 biased spherical probes extended on 50 m long wire booms, 90 degrees apart
in the spin plane, giving a 100 m baseline for each of the two spin-plane electric field components. EFI-HFA
consists of 6 x 1.25 m long monopoles, forming 3 dipolar antennas crossed at 90 degrees to each other. In addition
to the sensors, EFI contains HFA and SDP pre-amplifiers, as well as bias electronics boards (BEBs) hosted in
the man electronics box of the Field and Wave processor (FWP). As THOR spacecraft has a sun-pointing spin
axis, EFI-SDP measures the electric field in the plane approximately orthogonal to the sun using long wire
booms. The sun-pointing attitude greatly reduces errors due to wake effects and asymmetric photoelectron clouds,
enabling the highly accurate in comparison to earlier missions ±0.1 mV/m near-DC electric field measurements.
Interferometry using the electric field probes can be used to infer wavelengths and scale sizes at the smallest scales
in the plasma. EFI also measures the floating potential of the satellite, which can be used to estimate the plasma
density at very high time resolution (up to a few hundred Hz). The sun-pointing attitude greatly reduces changes in
the illuminated area, and hence the associated spin-dependent errors. In combination with densities derived from
the observed plasma frequency emission line, EFI monitors the plasma density from DC to a few hundred Hz.

Trvalý link: http://hdl.handle.net/11104/0259866