First-principles closure for cross-field electron mobility in Hall thrusters

In Hall thrusters (radial $B$ of order 100 to 300 G, xenon propellant), the measured cross-field electron mobility exceeds the classical collisional value by one to three orders of magnitude and varies along the channel. Derive a closure $\mu_{\mathrm{perp}}(z)$ from local plasma parameters that, inserted in fluid or hybrid codes, predicts thrust, discharge current and breathing-mode oscillations to within 10 percent without tuning, across thrusters and operating points.

A closure that predicts measured performance of at least two different thrusters across operating points without adjustment.