Deep Dielectric Breakdown of Silicates: Microstructural Damage and Implications for Lunar Space Weathering

Abstract

Solar energetic particle events electrically charge the lunar surface and may produce electric fields sufficient to induce dielectric breakdown in regolith grains. We irradiated series of silicate minerals with electrons to determine their physical and chemical response to deep dielectric charging and subsequent breakdown. Two electrical phenomena, flashovers and subsurface dielectric breakdown, produced damage including erosional and eruptive channels, surface pits, comminuted grains, and melt and vapor deposits. Iron abundances strongly affected the scale of damage and the minimum fluence required to reach dielectric breakdown; higher iron abundances required higher fluences to reach the breakdown threshold and produced more areally dense damage with each event. If dielectric breakdown is a prominent space-weathering process on the Moon, it should contribute to differential weathering signatures across the lunar surface as a function of target composition.

Keywords

• Lunar regolith
• Solar energetic particles