Example of RPW measurements and n_e estimation. (a) Dynamic spectra of the antenna 1 and antenna 2 voltage signal. The plasma line, corresponding to f_pe is visible as the enhanced signal between ~50–80 kHz. The red dots correspond to the low-cadence, non-continuous reference n_TNR (b) Density estimated using calibration method of RPW data (black). The fit is used based on TNR plasma line detection (red circles). For comparison, we show the resulting n_e from the single-fit estimation (blue), which does not account for the change in slope of the V_ps − ln(n_TNR) relationship. (c) Residual values (n_TNR − n_e)/n_e × 100 of the double-fit (black) and single-fit (blue) estimation methods. This example corresponds to a section of the calibration interval in Fig. 5.