The Effect of Work Function on Dust Charging and Dynamics on the Airless Celestial Body

The charged dust on the surface of airless celestial bodies, such as the moon and asteroids, is a threat to space missions. Further research on the charged dust will contribute to the success of space missions. In this paper, we study the charging and dynamics of dust particles with different work functions. By integrating the photoelectron energy distribution function over four illuminated areas with different work functions, we evaluated the photoelectron concentration in these four areas. At each area, using the photoelectron concentration, we solve the dust charging and dynamics equations with two different gravitational acceleration values. The results reveal that the dust with a larger work function can reach higher equilibrium states. These states include dominant photoelectron-related charging currents, charge numbers, and levitation heights. We suggest that the equilibrium states all hold a clear inverse relationship with the work functions of dust particles when the solar zenith angle varies from 0 to 90 degrees, displaying consistent trends under different gravitational accelerations. We also find that dust particles seem unable to stably levitate at a critical solar zenith angle. The value of this critical SZA follows the same rule subjected to the work function.