Magnetic curvature drift (${\mathbf{v}}_{\kappa }=(v_{\parallel }^2/{\Omega }_s)\mathbf{b}\times \mathbf{\kappa }$)

The transverse guiding center drift associated with magnetic field-line curvature. The signed cyclotron frequency ${\Omega }_s=q_{s}B/(m_{s}c)$ makes oppositely charged species drift oppositely at fixed velocity. The resulting species-dependent response is retained in slow drift-scale instabilities.