Gradient-B drift (${\mathbf{v}}_{\nabla B}=\mu \mathbf{b}\times \nabla B/{\Omega }_s$)

The transverse guiding center drift produced by a magnetic field strength gradient, with first adiabatic invariant $\mu =v_{\perp }^2/(2B)$ and signed cyclotron frequency ${\Omega }_s$. Together with magnetic curvature drift, it produces velocity-dependent transverse transport.