  The correlation between the plasma density measured in space and the surface
potential of an electrically conducting satellite body with biased electric
field detectors has been recognized and used to provide density proxies.
However, for Parker Solar Probe, this correlation has not produced quantitative
density estimates over extended periods of time because it depends on the
energy dependent exponential variation of the photoemission spectrum, the
electron temperature, the ratio of the biased surface area to the conducting
spacecraft surface area, the spacecraft secondary or thermal emission, the
spacecraft distance from the Sun, etc. In this paper the density as a function
of time and frequency to frequencies as high as the electron gyrofrequency is
determined through least squares fits of a function of the spacecraft potential
to the plasma density measured on the Parker Solar Probe. This function allows
correction for the many effects on the spacecraft potential other than that due
to the plasma density. Some examples of plasma density obtained from this
procedure are presented.
