wotivted y the need to hndle omplex oundry onditions eiently nd urtely in prtileEinEell @sgA simultionsD this pper presents threeEdimensionl @QhA liner immersed nite element @spiA method with nonEhomogeneous ux jump onditions for solving eletrostti eld involving omplex oundry onditions using strutured meshes independent of the interfeF his method trets n ojet oundry s prt of the simultion domin nd solves the eletri eld t the oundry s n interfe prolemF sn order to resolve hrging on dieletri surfeD new Qh liner spi sis funtion is designed for eh interfe element to pture the eletri eld jump on the interfeF xumeril experiments re provided to demonstrte the optiml onvergene rtes in L P nd H I norms of the spi solutionF his new spi method is integrted into sg method for simultions involving hrging of omplex shped dieletri surfe in plsmF e numeril study of plsmEsurfe intertions t the lunr termintor is presented to demonstrte the ppliility of the new methodF £ Key words: interface problems, non-homogeneous ux jump conditions, immersed nite elements, particle in cell, plasma environments, lunar surface.

The physics of ionic electrospray propulsion spans multiple length scales. This paper combines a molecular dynamics model, a particle–particle model, and a particle-in-cell model to investigate the physics of ionic electrospray propulsion over 9 orders of magnitude in length scale. The combined models are applied to simulate beam emission for an ionic electrospray propulsion system with porous emitter tips and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid propellant from the emission site to the downstream plume. Additionally, the impact of multiple emission sites from a single emitter tip is analyzed with regard to extractor grid interception and overall beam neutralization for bipolar thruster pairs. Results show that beams consisting of species of different masses (i.e., monomer and dimer species) are affected by particle–particle forces during acceleration and should not be treated as a superposition of independently accelerated species in macro-scale plume models. The activation of multiple emission sites also causes a noticeable increase in the beam’s spread, leading to increased intercepted current but relatively little adverse effects in the downstream plume region.

Reactive molecular dynamics simulations are carried out to investigate solar wind implantation on lunar surface. This study resolves both the chemical reactions and physical interactions of implantation, analyzes the effects from hydroxyl saturation, solar wind reflection, and water molecule sputtering, and quantifies the contribution of solar wind proton implantation on lunar water formation. The results show that, while solar wind implantation can lead to the formation of some hydroxyl groups and water molecules, the contribution by the implantation process itself is not significant enough to account for the observed lunar water content.

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