Photoelectron Sheath and Plasma Charging on the Lunar Surface: Semianalytic Solutions and Fully-Kinetic Particle-In-Cell Simulations


This article presents the derivation of semianalytic solutions to a new 1-D photoelectron sheath model near the lunar surface. The plasma species include the cold solar wind protons, drifting Maxwellian solar wind electrons, and Maxwellian photoelectrons emitted from the surface. The semianalytic model is then numerically solved to obtain profiles of quantities of interest as functions of the vertical distance from the surface. A fully-kinetic 3-D finite-difference (FD) particle-in-cell (PIC) code is then utilized to simulate the 1-D photoelectron sheath and the results agree well with the numerical solution to the semianalytic model. A κ -distribution for solar wind electrons is also implemented to the FD-PIC code to compare with the Maxwellian distribution. Results show that photoelectron sheath may reach as high as close to 100 m above the illuminated flat lunar surface near the terminator region and up to about 50 m near the equator region. Our results show that under average solar wind condition, the photoelectron sheath profiles obtained with Maxwellian and κ -distribution (with κ = 4.5 ) are very close for 1-D numerical results.


Mathematics and Statistics

Second Department

Mechanical and Aerospace Engineering

Keywords and Phrases

Particle-In-Cell (PIC); Photoelectron Sheath; Semianalytic Solution

International Standard Book Number (ISBN)

0093-3813; 1939-9375

Document Type

Article - Journal

Document Version


File Type





© 2021 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

21 Sep 2021