Rotating Particle in the Near Field of the Surface at Arbitrary Direction of Angular Velocity Vector

TL;DR

This paper investigates the electromagnetic interactions of a rotating particle near a surface, revealing its tendency to align perpendicular to the surface and exhibit precessional motion, with general expressions for forces and torques derived.

Contribution

It provides the first general expressions for electromagnetic forces, heating rates, and torques on a rotating particle with arbitrary angular velocity orientation near a surface.

Findings

Particle tends to slow down and reach thermal equilibrium.

Particle's angular velocity vector precesses around the surface normal.

Particle aligns perpendicular to the surface over time.

Abstract

We study the fluctuation-electromagnetic interaction between a small rotating particle with an arbitrary direction of angular velocity vector and evanescent field of the heated surface, and obtain the general expressions for the force of attraction, rate of heating and components of torque. The particle rotation dynamics is analyzed. It is shown that during most time of motion the particle slows down provided that a quasiequilibrium thermal state has been reached, while at any initial direction of the angular velocity vector it tends to orient perpendicular to the surface with spin direction depending on the initial conditions. Moreover, the angular velocity vector executes precessional motion around surface normal.