Abstract
Abstract
In this article, the effect of the finite conductive surface area of a satellite on the use of satellite-based Langmuir probes is reviewed in light of the basic theory of asymmetric double Langmuir probes (ADLPs). Recent theoretical and experimental studies have discussed electron sheath/presheath formation and the electron Bohm criterion along with their implications for satellite-based Langmuir probes. The effects predicted by the latest theory of the electron Bohm criterion were not experimentally observed and the experimental results remain supportive of a critical area ratio (A
L/A
S)crit = (m
i/(2.3m
e))1/2 between the probe area A
S and the satellite area A
L as conventionally believed. A satellite-based Langmuir probe must satisfy this criterion to physically act as a single Langmuir probe. However, experimental investigations also found that high-energy electrons adversely affect (A
L/A
S)crit and a Langmuir probe’s signal quality by giving additional electron current to A
L. Based on these results, a number of limitations of the maximum probe area are derived when designing satellite-based Langmuir probes, with consideration of both the aim of the satellite and the plasma where the satellite-based probe works. These proposed measures are expected to only partially alleviate the effect of the inadequate satellite surface area on the application of satellite-based Langmuir probes. Using a larger satellite to carry a Langmuir probe remains the most viable means to obtain precise space plasma parameters.
Funder
China Postdoctoral Science Foundation
Director Funding of Hefei Institutes of Physical Science, Chinese Academy of Sciences
National Natural Science Foundation of China