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Radio Waves. Main task Investigate radio emissions of magnetospheric and atmospheric processes with ground- and space-based radio antennas including calibration of the antenna systems Main research topics

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radio waves
Radio Waves

Main task

  • Investigate radio emissions of magnetospheric and atmospheric processes with ground- and space-based radio antennas including calibration of the antenna systems

Main research topics

    • Calibration of antennas on spacecraft by numerical simulations, rheometry, anechoic chamber measurements, and in-flight
    • Radiophysics of magnetized planets and the Sun: Solar radio emissions, Auroral kilometric radiation (AKR) at Earth, Jovian hectometric (HOM) and decametric (DAM) emission, Saturn kilometric radiation (SKR) and narrowband emissions
    • Radio emissions from lightning on planets with focus on Saturn

Refereed publications (since Jan 2013)

    • Total: 12 (first author: 2)

Educational activities (since Jan 2013)

    • 1 completed master thesis
    • 1 ongoing doctoral thesis

IWF/ÖAW

who are we
Who are we?

Lead: Georg Fischer

  • Staff: M. Boudjada, M. Kapper (50%), J. Pagaran, M. Panchenko, (M. Sampl left, H.O. Rucker retired)
  • Students: PhD: C. Weber;Master: G. Rief (thesis completed)

Cooperation within IWF

  • Exoplanetary radio emissions (Lammer et al., Khodachenko et al.)
  • Auroral and magnetospheric processes(Nakamura et al.)
  • Instrument developers (Steller et al.), Solar Orbiter RPW

Key external collaboration

USA: Dept. of Physics & Astronomy/Univ. of Iowa, Caltech Pasadena, Hampton Univ., NASA-GSFC; France: LESIA Meudon, LATMOS CNRS Guyancourt; Germany: Univ. Dresden, Astrophysical Inst. Potsdam; Ukraine: Inst. for Radio Astronomy; Russia: Inst. of Applied Physics/RAS; Sweden: Swedish Inst. of Space Physics

IWF/ÖAW

anechoic chamber measurements
Anechoic Chamber Measurements
  • Solar Orbiter hardware model 1:50 for anechoic chamber measurements of RPW antenna system
  • Measurements of antenna pattern from 8-20 MHz (400-1000 MHz in chamber) and antenna S-parameters
  • Construction of a corresponding pre-amplifier for model
  • Numerical computer simulations with FEKO to gain surface currents on patch model, calculate antenna parameters (effective lengths, impedances), modeling of antenna heating circuit& influence of radii, comparison with anechoic chamber results
  • Solar Orbiter launch planned for Jan 2017

IWF/ÖAW

in flight calibration of stereo waves
In-flight Calibration of STEREO/WAVES
  • Effective length vectors were determined using the terrestrial AKR observed in early stage of STEREO mission during roll maneuvers
  • Least squares method combined with a genetic algorithm was applied to fit the best physical model to the observations
  • Accurate results confirm the results of rheometry(experimental method with model in electrolytic tank) and numerical wire-grid simulation
  • Our effective length vectors are recommended as a basis for future evaluation of SWAVES data (direction-finding & polarization)

STEREO configuration (upper left), dynamic spectra of AKR recorded by STEREO-B during roll maneuvers (lower left) and modeled signals (red lines) compared to observations (right) [Panchenko et al., 2014]

IWF/ÖAW

jovian r adio emissions
Jovian Radio Emissions
  • Periodic bursts of non-Io DAM:
  • Period ~10.07 h (~1.5% longer than Jupiter System III rotation)
  • Correlation with solar wind
  • Possible origin: interchange instability in the Io plasma torus triggered by solar wind pulses
  • Investigation of Io plasma torus:
  • Occultation of hectometric emission
  • Radio remote sensing of Io plasma ribbon & estimation of electron density
  • Study of local time dependence

STEREO Waves and Cassini RPWS spectra of Jovian periodic bursts [Panchenko et al., 2013]

IWF/ÖAW

ground based radio observations
Ground-Based Radio Observations
  • Detection of periodic Jovian bursts from the ground
  • Simultaneous long lasting observations using STEREO/WAVES and the ground-based radio telescope URAN-2 (Poltava, Ukraine)
  • Non-Io DAM periodic bursts observed up to 25 MHz with resolution of fine structures
  • Bursts observed with LH & RH circular polarization components from both hemispheres
  • Detection of Saturn lightning from the ground
  • First ground-based detection of Saturn lightning with UTR-2 radio telescope (ON-OFF beams)
  • Good agreement with Cassini/RPWS lightning observations despite radio interferences
  • High temporal resolution observations indicate similar structures of Saturn lightning to terrestrial intracloud lightning

[Konovalenko et al., 2013]

IWF/ÖAW

evolution of the great white spot
Evolution of the Great White Spot
  • GWS (Great White Spot) is a large scale disturbance in Saturn’s atmosphere (a giant thunderstorm, where we detect lightning radio emissions with the Cassini RPWS instrument)
  • Lightning flashes detected from 5 Dec. 2010 to 28 Aug. 2011
  • Five GWS events in history: 1876, 1903, 1933, 1960, 1990
  • GWS consists of head (~10,000 km in latitude, lightning activity with rate ~10 s-1), and tail (300,000 km around Saturn)
  • Head spawned anticyclonic vortices and flashes were optically observed in blue light on dayside (in cyclonic gaps)
  • Large anticyclonic vortex (AV) collided with head in mid-June 2011 leading to decrease in flash rate and final demise
  • Total lightning power: 1013 W, Storm total power: 1017 W

[Dyudina et al., 2013]

IWF/ÖAW

future plans 2015 2018
Future Plans: 2015-2018
  • Antenna calibration
  • Antenna optimization studies for RPWI of JUICE
  • Solar Orbiter antenna calibration with rheometry
  • Solar & planetary radio emissions
  • Stereoscopic space- and ground-based observations of Jovian DAM and Solar radio emissions (Stereo WAVES, Juno, Solar Orbiter)
  • Ground-based radio observations (UTR-2, NenuFAR, LOFAR) with search for exoplanetary radio emissions
  • Long-term behavior of Saturn kilometric radiation and narrowband radio emissions (Cassini RPWS)
  • Lightning radio emissions
  • Continued analysis of Saturn lightning
  • Radio Wave Group has Co-I ships of Cassini/RPWS, Stereo WAVES, Solar Orbiter RPW and JUICE RPWI (data access)

IWF/ÖAW

thank you
Thank you

IWF/ÖAW

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