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Quasi‐Thermal Noise (QTN) spectroscopy is a reliable diagnostic routinely used for measuring electron density and temperature in space plasmas. The observed spectrum depends on both antenna geometry and plasma kinetic properties. Parker solar probe (PSP), launched in 2018, is equipped with an antenna system consisting of two linear dipoles with a significant gap between the antenna arms. Such a configuration, not utilized on previous missions, cannot be completely described by current models of the antenna response function. In this work, we calculate the current distribution and the corresponding response function for the PSP antenna geometry, and use these results to generate synthetic QTN spectra. Applying this model to the Encounter 7 observations from PSP provides accurate estimations of electron density and temperature, which are in very good agreement with particle analyzer measurements. Plain Language Summary: Parker solar probe (PSP) is a NASA mission that is travelling much closer to the Sun than any previous spacecraft. A primary consequence of this specific trajectory are multiple adaptations in the design of instruments (radio instruments, magnetometers, particle detectors etc.) and their complex accommodations on the spacecraft. This article investigates effects of the specific PSP radio antenna geometry to high‐frequency electric field observations. We apply Quasi‐Thermal Noise Spectroscopy, a well established method for determining plasma density and temperature, to PSP radio observations using dipole antennas, and validate the results by comparing the parameter values from radio observations to the ones obtained by particle analyzers onboard PSP. Key Points: We model the antenna response for the unique geometry of linear dipole antenna containing a gap between armsThis antenna response is used to improve plasma parameters determination from the observed quasi‐thermal noise spectrumThe proposed model yields derived electron parameters consistent with those from the SWEAP/SPAN instrument suite onboard Parker solar probe [ABSTRACT FROM AUTHOR]

During Parker Solar Probe's first two orbits, there are widespread observations of rapid magnetic field reversals known as switchbacks. These switchbacks are extensively found in the near-Sun solar wind, appear to occur in patches, and have possible links to various phenomena such as magnetic reconnection near the solar surface. As switchbacks are associated with faster plasma flows, we questioned whether they are hotter than the background plasma and whether the microphysics inside a switchback is different to its surroundings. We have studied the reduced distribution functions from the Solar Probe Cup instrument and considered time periods with markedly large angular deflections to compare parallel temperatures inside and outside switchbacks. We have shown that the reduced distribution functions inside switchbacks are consistent with a rigid velocity space rotation of the background plasma. As such, we conclude that the proton core parallel temperature is very similar inside and outside of switchbacks, implying that a temperature–velocity (T–V) relationship does not hold for the proton core parallel temperature inside magnetic field switchbacks. We further conclude that switchbacks are consistent with Alfvénic pulses travelling along open magnetic field lines. The origin of these pulses, however, remains unknown. We also found that there is no obvious link between radial Poynting flux and kinetic energy enhancements suggesting that the radial Poynting flux is not important for the dynamics of switchbacks. [ABSTRACT FROM AUTHOR]

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. Key Points: Wind spacecraft quasi‐thermal noise (QTN) spectra is filtered to independently measure electron core and halo parametersAn automated algorithm accounts for a variety of sources of signal contamination, allowing the processing of large numbers of QTN spectraElectron density and core temperature are determined with an accuracy of the order of 5% for over 75 days of solar wind observations [ABSTRACT FROM AUTHOR]