ARTEMIS Observations of Waves in Laminar and Turbulent Interplanetary Shocks
Abstract
Electromagnetic waves are one method through which interplanetary shocks dissipate energy. The types of waves observed depend on the properties of the shock and of the ion and electron distributions. Turbulent shocks are shocks where magnetic field fluctuations comparable to the size of the ramp itself are present within the DC magnetic field of the shock ramp. The effects of these fluctuations on wave generation have only been studied in detail for a set of events observed by Wind. Using a set of twelve shock events observed by the two ARTEMIS satellites possessing waveform burst captures near the shock ramp, we compare the types and number of high frequency waves observed near turbulent shock ramps to those observed near shock ramps with a more laminar structure in the DC magnetic field.
ARTEMIS observations provide a unique opportunity to study both electromagnetic and electrostatic waves within and near shock ramps, as well as the interactions of these waves with features in electron and ion distributions. The waveform captures include both magnetic search coil and electric field data and are the longest waveform burst captures obtained to date by spacecraft that regularly observe interplanetary shocks. These captures can resolve waves in the range of few Hz to 8 kHz. Due to the length of these captures, the full structure of a wave packet and the variability of wave modes through the shock structure can be studied. Waves were identified and classified as either ion acoustic-like, electrostatic solitary, whistler mode, lower hybrid, or electron cyclotron drift instability waves. Ion acoustic-like waves are in the frequency band of ion acoustic waves, but possess properties deviating from the standard description, including frequency dispersion and elliptical polarization. Preliminary results suggest that there are more wave packets per unit time near turbulent shock ramps than for laminar ramps. The amplitudes of individual wave packets appear to be independent of the different shock types.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSH31C3637D
- Keywords:
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- 2772 Plasma waves and instabilities;
- MAGNETOSPHERIC PHYSICSDE: 7845 Particle acceleration;
- SPACE PLASMA PHYSICSDE: 7846 Plasma energization;
- SPACE PLASMA PHYSICSDE: 7851 Shock waves;
- SPACE PLASMA PHYSICS