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Electrostatic charging of permanently shadowed craters on the Moon


 An open question of the electrostatic charge development on the lunar surface in the electron-rich region within the permanently shadowed craters (PSCs) is addressed. We propose that the fine dust grains on the crater surface may act as efficient field emission centres generating electrons via quantum field tunnelling. This return current may be sufficient to establish a steady-state dynamical equilibrium for the surface-plasma system. This leads to the crater surface attaining a finite electric potential. Our analysis illustrates that the PSC having ∼100 nm dust, covering 1 per cent of the surface area within the electron-rich region, may acquire a negative potential of few hundred volts in the steady-state condition.