Solar Wind Electron Parameters Determination on Wind Spacecraft Using Quasi‐Thermal Noise Spectroscopy

Abstract

Quasi‐thermal noise (QTN) spectroscopy has been extensively used as an accurate tool to measure electron density and temperature in space plasmas. If the antenna length to radius ratio is sufficiently large, a typical measured spectrum clearly shows a resonance at the electron plasma frequency and a lower frequency plateau that quantify the electron distributions. The Wind spacecraft, with its long, thin antennas, is considered the mission par excellence for the implementation of the QTN method. However, a major issue in applying QTN spectroscopy is contamination from signals other than the ubiquitous plasma noise in the vicinity of plasma frequency, affecting the measured spectra and confusing their physical interpretation. In this work, we present a new method for selecting the observations of uncontaminated QTN, distinguishing it from other plasma and spacecraft effects. The selected measurements are used to obtain accurate values for both thermal and suprathermal electron parameters. Testing of the method on 1.5M observations under various conditions in the solar wind, including slow and fast wind and solar transients, confirms the reliability and accuracy of the method with no systematic flaws.

Plasma Parameters From Quasi‐Thermal Noise Observed by Parker Solar Probe: A New Model for the Antenna Response

“…In this work, we focus on V1‐V2 dipole, that operated with no bias during 05:48–05:52 and 17:48–17:52 each day. In lieu of applying an algorithm that filters out low‐frequency non‐QTN signal components, such as wave activity and instrument gain effects, from the spectrum (Martinović et al., 2020), we use only the signal above 100 kHz, corresponding to approximately 0.25 f p , avoiding the resistively coupled antenna regime (Bonnell et al., 2019). We derive the plasma parameters from both the full resolution observations, and 1 min median values, with medians having a purpose of removing any short term signal pollution.…”

“…Quasi‐Thermal Noise (QTN) spectroscopy, theoretically described more than half a century ago (Andronov, 1966; Fejer & Kan, 1969), is a powerful tool to diagnose space plasmas using a passive electric antenna related to a sensitive radio receiver. Since this method was fully expanded to solar wind and pioneered aboard ISEE‐3 (Hoang et al., 1980; Meyer‐Vernet, 1979), it has been routinely used to infer in‐situ electron densities and temperatures on various missions in the solar wind: IMP‐6 (Kellogg, 1981), Ulysses (Issautier et al., 1996, 1999; Le Chat et al., 2011; Maksimovic et al., 1995), Wind (Issautier et al., 2005; Maksimovic et al., 1998; Martinović, et al., 2020), STEREO (Martinović et al., 2016; Zouganelis et al., 2010), and planetary missions such as Cassini (Moncuquet et al., 1997, 2005).…”

Plasma Parameters from Quasi-Thermal Noise Observed by Parker Solar Probe: A New Model for the Antenna Response

“…In this work, we focus on V1-V2 dipole, that operated with no bias during 05:48-05:52 and 17:48-17:52 each day. In lieu of applying an algorithm that filters out low-frequency non-QTN signal components, such as wave activity and instrument gain effects, from the spectrum (Martinović et al, 2020), we use only the signal above 100 kHz, corresponding to approximately 0.25f p , avoiding the resistively coupled antenna regime (Bonnell et al, 2019). We derive the plasma parameters from both the full resolution observations, and 1 min median values, with medians having a purpose of removing any short term signal pollution.…”

“…Quasi-Thermal Noise (QTN) spectroscopy, theoretically described more than half a century ago (Andronov, 1966;Fejer & Kan, 1969), is a powerful tool to diagnose space plasmas using a passive electric antenna related to a sensitive radio receiver. Since this method was fully expanded to solar wind and pioneered aboard ISEE-3 (Hoang et al, 1980;Meyer-Vernet, 1979), it has been routinely used to infer in-situ electron densities and temperatures on various missions in the solar wind: IMP-6 (Kellogg, 1981), Ulysses (Issautier et al, 1996(Issautier et al, , 1999Le Chat et al, 2011;Maksimovic et al, 1995), Wind (Issautier et al, 2005;Maksimovic et al, 1998;Martinović, et al, 2020), STEREO (Martinović et al, 2016;Zouganelis et al, 2010), and planetary missions such as Cassini (Moncuquet et al, 1997(Moncuquet et al, , 2005.…”

Total Electron Temperature Derived from Quasi-Thermal Noise Spectroscopy In the Pristine Solar Wind: Parker Solar Probe Observations

“…The Quasi-thermal noise (QTN) technique yields accurate electron density and temperature measurements in the solar wind. It has been used in a number of space missions (e.g., Meyer-Vernet 1979;Meyer-Vernet et al 1986, 1993Meyer-Vernet et al 2017;Issautier et al 1999bIssautier et al , 2001aIssautier et al ,c, 2005Issautier et al , 2008Maksimovic et al 1995Maksimovic et al , 2005aMoncuquet et al 1995Moncuquet et al , 1997Moncuquet et al , 2005Moncuquet et al , 2006Martinović et al 2020;Le Chat et al 2011;Salem et al 2001;Lund et al 1994;Schippers et al 2013). Recent investigations (see Moncuquet et al 2020;Maksimovic et al 2020;Martinović et al 2022) have already applied this technique on PSP based on electric voltage spectra acquired by the Radio Frequency Spectrometer (RFS/FIELDS) (Pulupa et al 2017).…”