Dust observations with antenna measurements and its prospects for observations with Parker Solar Probe and Solar Orbiter

The electric and magnetic field instrument suite FIELDS on board the NASA Parker Solar Probe and the radio and plasma waves instrument RPW on the ESA Solar Orbiter mission that explore the inner heliosphere are sensitive to signals generated by dust impacts. Dust impacts have been observed using electric field antennas on spacecraft since the 1980s and the method was recently used with a number of space missions to derive dust fluxes. Here, we consider the details of dust impacts, subsequent development of the impact generated plasma and how it produces the measured signals. We describe empirical approaches to characterise the signals and compare these in a qualitative discussion of laboratory simulations to predict signal shapes for spacecraft measurements in the inner solar system. While the amount of charge production from a dust impact will be higher near the Sun than observed in the interplanetary medium before, the amplitude of pulses is determined by the recovery behaviour that is different near the Sun since it varies with the plasma environment

Quantification of magnetosphere–ionosphere coupling timescales using mutual information : response of terrestrial radio emissions and ionospheric–magnetospheric currents

Auroral kilometric radiation (AKR) is a terrestrial radio emission excited by the same accelerated electrons which excite auroral emissions. Although it is well correlated with auroral and geomagnetic activity, the coupling timescales between AKR and different magnetospheric or ionospheric regions have yet to be determined. Estimation of these coupling timescales is non-trivial as a result of complex, non-linear processes which rarely occur in isolation. In this study, the mutual information between AKR intensity and different geomagnetic indices is used to assess the correlation between variables. Indices are shifted to different temporal lags relative to AKR intensity, and the lag at which the variables have the most shared information is found. This lag is interpreted as the coupling timescale. The AKR source region receives the effects of a shared driver before the auroral ionosphere. Conversely, the polar ionosphere reacts to a shared driver before the AKR source region. Bow shock interplanetary magnetic field BZ is excited about 1 h before AKR enhancements. This work provides quantitatively determined temporal context to the coupling timelines at Earth. The results suggest that there is a sequence of excitation following the onset of a shared driver: first, the polar ionosphere feels the effects, followed by the AKR source region and then the auroral ionosphere

Diagnostics of the Solar Wind Plasma

International audienceThe solar wind is a fully ionized plasma, coming from the outer atmosphere of the Sun, the so-called solar corona, which expands as a supersonic flow into the interplanetary medium [55]. The first observations indicating that the Sun might be emitting a wind were made by Biermann in 1946 of comet tails [1], which are observed to point away from the Sun. Comets usually exhibit two tails: a dust tail driven by the radiation pressure and a plasma tail, which points in slightly different directions pushed by the ``solar corpuscular radiation'' of the Sun. In 1958, E.N. Parker explained theoretically this ``particle radiation'' using a simple fluid model [55], showing that the solar atmosphere is not in hydrostatic equilibrium but must expand into the interplanetary medium as a wind. The existence of this solar wind was debated until it was indeed confirmed by spacecraft Lunik 2 and 3 [16] and continuously observed by Mariner 2 [53]. The Parker theory is discussed fully in Chap. 7 (Velli)

Profil de température électronique mesuré dans le vent

National audienc

Ulysse et les mystères du vent solaire

National audienc

Une revue de la mission STEREO

National audienc

La mission spatiale Ulysse: la fin d'une odyssée

National audienc

Propriétés à grande échelle du vent solaire : dernières données de la sonde Ulysse

National audienc

Some Basic Aspects of the Solar Wind

International audienc

Plasma radio diagnostics on Ulysses

International audienc