Ambipolar electrostatic field in dusty plasma

We study the effect of negatively charged dust on magnetic-field-aligned polarisation electrostatic field ( $\boldsymbol {E}_{\parallel }$ ) using Cassini's RPWS/LP in situ measurements during ‘ring-grazing’ orbits. derive a general expression for and estimate first time $\lVert \boldsymbol } \rVert$ (approximately $10^{-5} \, \text {V}\, {m}^{-1}$ near Janus Epimetheus rings. further demonstrate that presence close to ring plane $\vert {Z} \vert \lesssim 0.11 {R}_{s}$ amplifies by at least one order magnitude reverses its direction due gravitational inertial forces. Such reversal confines electrons magnetic equator within dusty region, around $0.047 above plane. Furthermore, we discuss role collision terms, particular ion–dust drag force, amplifying . These results imply dust, as small nanometres size, can have significant influence plasma transport, ambipolar diffusion along lines, so their must be taken into account when studying such dynamical processes.