The underexposed effect of elastic electron collisions in dusty plasmas

Dusty plasmas are ubiquitous in the universe and are widely used in laboratory and industrial applications, and yet elements of theoretical understanding of the interaction between dust grains with their environment remains incomplete. The authors present experimental measurements that challenge the collisionless electron assumptions widely used in current models of dusty plasmas. Dusty plasmas comprise a complex mixture of neutrals, electrons, ions and dust grains, which are found throughout the universe and in many technologies. The complexity resides in the chemical and charging processes involving dust grains and plasma species, both of which impact the collective plasma behavior. For decades, the orbital-motion-limited theory is used to describe the plasma charging of dust grains, in which the electron current is considered collisionless. Here we show that the electron (momentum transfer) collision frequency exceeds the electron plasma frequency in a powder-forming plasma. This indicates that the electron current is no longer collisionless, and the orbital-motion-limited theory may need corrections to account for elastic electron collisions. This implication is especially relevant for higher gas pressure, lower plasma density, and larger dust grain size and density.

Automated summary

Dusty plasmas are common in the universe and have various applications, but the theoretical understanding of the interaction between dust grains and their environment is still incomplete. Experimental measurements presented by the authors challenge the widely used collisionless electron assumptions in current models of dusty plasmas. The findings suggest that the electron current may not be collisionless in certain plasma conditions, which could require corrections to existing theories.