Does sheath expansion around Langmuir probes, used near material boundaries, depend only on the probe bias relative to the plasma potential?

Langmuir probes (LPs) measure an unphysically positive plasma potential in the presheath of low temperature plasma, near conducting boundaries at which ion rich sheaths form [Li et al., Plasma Sources Sci. Technol. 29 (2020) 025015]. The difference between plasma potential profiles measured by LPs and emissive probes (EPs), in the presheath, is consistent with the effects of ion flow, the signature of which is known to appear in the electron branch of the current-voltage characteristic of LPS. We present experimental evidence that the electron density is also overestimated by standard analysis in the presheath, and that the two anomalies are interrelated, having to do with ion flow near the boundary where an ion rich sheath forms. We exhibit evidence to support this claim for experiments performed in weakly collisional (λ_{mean-free-path} >>λ_D), low pressure (P_neutral ≤ 1 mTorr), low temperature (kT_e of order 1 eV), single ion species plasma, where the feedstock gas is Ar or He or Xe or Kr. We also attempt to perform Laser-induced Fluorescence measurements to locate the sheath edge to aid in demarcating the presheath region in Kr plasma specifically.