Evidence that Interaction with the Spacecraft Plasma Wake Generates Plasma Waves Close to the Electron Cyclotron Frequency in the Near-Sun Solar Wind

Malaspina, D.; Tigik, Sabrina F.; Vaivads, A.

doi:10.3847/2041-8213/ac8c8f

Cited by 4 publications

(4 citation statements)

References 28 publications

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“…Similar structures with magnetic field magnitude depletion were observed in the vicinity of the Earth bow shock by the four MMS spacecraft with hightime resolution electron measurements aboard (Ahmadi et al 2018), and these observations nicely confirm our assumptions highlighting the trapped hot electron population. Such distribution (with the proper plasma temperature) can guide the generation of whistler waves propagating along and opposite the background magnetic field through the cyclotron instability (Drake et al 2015;Agapitov et al 2018;Ahmadi et al 2018;Malaspina et al 2022;Tigik et al 2022). For the magnetic hole, which is in the rest with respect to the background core plasma, i.e., propagating with the bulk solar wind velocity, such a distribution is shown schematically in Figure 12(e).…”

Section: Discussionmentioning

confidence: 99%

“…These periods of whistler wave activity are interspersed with higher frequency electron Bernstein modes in the range of f ce and its harmonics (Malaspina et al 2020). Recent work has demonstrated that the observed electron Bernstein modes are most likely generated by the interaction between the solar wind and the Parker Solar Probe spacecraft wake (Malaspina et al 2022;Tigik et al 2022). Nonetheless, electron Bernstein waves are found to preferentially occur in regions of exceptionally lowamplitude magnetic turbulence, termed quiescent regions (Short et al 2022).…”

Section: Introductionmentioning

confidence: 99%

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Whistler Wave Observations by Parker Solar Probe During Encounter 1: Counter-propagating Whistlers Collocated with Magnetic Field Inhomogeneities and their Application to Electric Field Measurement Calibration

Karbashewski

Agapitov

Kim

et al. 2023

ApJ

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Observations of the young solar wind by the Parker Solar Probe (PSP) mission reveal the existence of intense plasma wave bursts with frequencies between 0.05 and 0.20f ce (tens of hertz up to ∼300 Hz) in the spacecraft frame. The wave bursts are often collocated with inhomogeneities in the solar wind magnetic field, such as local dips in magnitude or sudden directional changes. The observed waves are identified as electromagnetic whistler waves that propagate either sunward, anti-sunward, or in counter-propagating configurations during different burst events. Being generated in the solar wind flow, the waves experience significant Doppler downshift and upshift of wave frequency in the spacecraft frame for sunward and anti-sunward waves, respectively. Their peak amplitudes can be larger than 2 nT, where such values represent up to 10% of the background magnetic field during the interval of study. The amplitude is maximum for propagation parallel to the background magnetic field. We (i) evaluate the properties of these waves by reconstructing their parameters in the plasma frame, (ii) estimate the effective length of the PSP electric field antennas at whistler frequencies, and (iii) discuss the generation mechanism of these waves.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Whistler Wave Observations by Parker Solar Probe During Encounter 1: Counter-propagating Whistlers Collocated with Magnetic Field Inhomogeneities and their Application to Electric Field Measurement Calibration

Karbashewski

Agapitov

Kim

et al. 2023

ApJ

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“…Because the antennas on the Parker Solar Probe are not much larger than the spacecraft body, it is possible, under certain geometric conditions, that one or more antennas might be in the vehicle wake to produce a spurious wave electric field. In fact, cases of spurious whistler waves have been reported [Malaspina et al, 2022]. To test for this possibility, Figure A2 gives the solar wind speed (panel (c)), the angle of the magnetic field from the Z-direction (panel (d)), the plasma density (panel (e)), and the ion temperature (panel f)).…”

Section: Appendixmentioning

confidence: 99%

Triggered Ion-acoustic Waves in the Solar Wind

Mozer

Vasko

Verniero

2021

ApJL

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For more than 12 hr beginning on 2021 January 18, continuous narrowband electrostatic emissions were observed on the Parker Solar Probe near 20 solar radii. The observed <1000 Hz frequencies were well below the local ion-plasma frequency. Surprisingly, the emissions consisted of electrostatic wave packets with shock-like envelopes, appearing repetitively at a ∼1.5 Hz rate. This repetitiveness correlated and was in phase with low-frequency electromagnetic fluctuations. The emissions were associated with simultaneously observed ion beams and conditions favorable for ion-acoustic wave excitation, i.e., Te/Ti ∼ 5. Based on this information and on their velocity estimates of about 100 km s−1, these electrostatic emissions are interpreted as ion-acoustic waves. Their observation demonstrates a new regime of instability and evolution of oblique ion-acoustic waves that have not been reported previously in theory or experiment.

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“…If a 15 minute interval has 10 or fewer wave detections, it is removed from consideration. The resulting wave identifications are also examined by eye to remove wake-generated waves near the local electron cyclotron frequency (Tigik et al 2022;Malaspina et al 2022a). The wake-generated waves are readily identified as near-harmonic bands of power at an approximately constant frequency close to the electron cyclotron frequency.…”

Section: Wave Identificationmentioning

confidence: 99%

Frequency-dispersed Ion Acoustic Waves in the Near-Sun Solar Wind: Signatures of Impulsive Ion Beams

Malaspina,

Ergun,

Cairns

et al. 2024

ApJ

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This work reports a novel plasma wave observation in the near-Sun solar wind: frequency-dispersed ion acoustic waves. Similar waves have previously been reported in association with interplanetary shocks or planetary bow shocks, but the waves reported here occur throughout the solar wind sunward of ∼60 solar radii, far from any identified shocks. The waves reported here vary their central frequency by factors of 3–10 over tens of milliseconds, with frequencies that move up or down in time. Using a semiautomated identification algorithm, thousands of wave instances are recorded during each near-Sun orbit of the Parker Solar Probe spacecraft. Wave statistical properties are determined and used to estimate their plasma frame frequency and the energies of protons most likely to be resonant with these waves. Proton velocity distribution functions are explored for one wave interval, and proton enhancements that may be consistent with proton beams are observed. A conclusion from this analysis is that properties of the observed frequency-dispersed ion acoustic waves are consistent with driving by cold, impulsively accelerated proton beams near the ambient proton thermal speed. Based on the large number of observed waves and their properties, it is likely that the impulsive proton beam acceleration mechanism generating these waves is active throughout the inner heliosphere. This may have implications for the acceleration of the solar wind.

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Evidence that Interaction with the Spacecraft Plasma Wake Generates Plasma Waves Close to the Electron Cyclotron Frequency in the Near-Sun Solar Wind

Cited by 4 publications

References 28 publications

Whistler Wave Observations by Parker Solar Probe During Encounter 1: Counter-propagating Whistlers Collocated with Magnetic Field Inhomogeneities and their Application to Electric Field Measurement Calibration

Whistler Wave Observations by Parker Solar Probe During Encounter 1: Counter-propagating Whistlers Collocated with Magnetic Field Inhomogeneities and their Application to Electric Field Measurement Calibration

Triggered Ion-acoustic Waves in the Solar Wind

Frequency-dispersed Ion Acoustic Waves in the Near-Sun Solar Wind: Signatures of Impulsive Ion Beams

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