Top panel: experimental spectral power acquired by the probe RPC-MIP operating in SDL mode on 20 March 2016 between 4:10 and 5:10 (UTC). Bottom panel: simulated spectral power with our model considering a vacuum sheath around the probe and a double-Maxwellian plasma. The input parameters for the simulation are n_h = 200 cm⁻³, n_c = 800 cm⁻³, T_h = 3.61 eV, T_c = 0.36 eV, and R = 120 cm. The dashed line curves correspond to the model when the sheath is neglected (see Sect. 3.2).