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Plasma density and temperature with Quasi-Thermal Noise Spectroscopy
General Description
Dataset Content
Data Caveats
Data Coverage
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Confidence Level Overview
The data in this data set are thermal plasma parameters derived from HFR spectra using the thermal noise spectroscopy theory. Every data has been reviewed by a scientist to ensure that all data included in this data set is scientifically consistent. When the data can not be provided during the selected intervals, the values are replaced by "NaN" (Not a Number) flags.
The Quasi Thermal Noise Spectroscopy analysis is using the FuH resonance for the determination of the electron core density. This determination depends on:
- the ability to identify the resonance among the other lines and noises present in the data at the same time;
- the operating spectral resolution, which defines the accuracy the the determination of FuH. Concerning the first item, the scientific evaluation step is ensuring that the detected FuH line is not another emission or a spurious detection.
The electron core temperature is dependent on the thermal plateau level below the Upper hybrid resonance peak. The accuracy of the temperature determination depends on the integration time (the longer reducing the statistical noise on the data). The core electron temperature determination is also highly dependent on the shot noise contamination induced by the impact of the charged particles on the antennas (proportional to f-2).
The shot noise is dominant in the lowest part of the HFR frequency band and may artificially increase the minimum QTN level, inducing an overestimate of the core temperature. For this reason, we rejected the spectra where the contribution of the shot noise is larger than 20% of the thermal plateau level below FuH in the provided dataset.
The Quality Flag on temperature QF is equal to 1 when the shot noise ratio is lower than 10%, and 0 when the ratio is comprised between 10% and 20%. For best quality data, we recommend to the user to use the data with QF=1. Note that the estimate of the core temperature is dependent on the calibration in V2/Hz of the RPWS/HFR receiver. Calibration may evolve with time and influence the thermal plateau level.
The value of the temperature finally also depends on the absolute flux calibration of the HFR, and thus may change in the future in when a new calibration is available.

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