Time domain structures and dust in the solar vicinity: Parker Solar Probe observations

TL;DR

This study analyzes Parker Solar Probe data to identify and characterize time domain structures and dust events in the solar vicinity, revealing their prevalence, properties, and potential origins related to plasma turbulence and electron holes.

Contribution

It provides the first detailed identification and statistical analysis of dust and TDS events near the Sun using high-resolution electric field data.

Findings

Detected over 10,000 electric-field structures, including 135 dust events and 238 TDS events.

Estimated 500-1000 TDS events and about 1000 dust events occurred during the observation period.

Identified bipolar TDS as electron holes and observed field-aligned currents associated with TDS.

Abstract

On April 5, 2019, while the Parker Solar Probe was at its 35 solar radius perihelion, the data set collected at 293 samples/sec contained more than 10,000 examples of spiky electric-field-like structures having durations less than 200 milliseconds and amplitudes greater than 10 mV/m. The vast majority of these events was caused by plasma turbulence. Defining dust events as those having similar, narrowly peaked, positive, single-ended signatures, resulted in finding 135 clear dust events, which, after correcting for the low detection efficiently, resulted in an estimate consistent with the 1000 dust events expected from other techniques. Defining time domain structures (TDS) as those having opposite polarity signals in the opposite antennas resulted in finding 238 clear TDS events which, after correcting for the detection efficiency, resulted in an estimated 500-1000 TDS events on this day. The TDS electric fields were bipolar, as expected for electron holes. Several events were found at times when the magnetic field was in the plane of the two measured components of the electric field such that the component of the electric field parallel to the magnetic field was measured. One example of significant parallel electric fields shows the negative potential that classified them as electron holes. Because the TDS observation rate was not uniform with time, it is likely that there were local regions below the spacecraft with field-aligned currents that generated the TDS.