PLASMA In the literature: open

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

In plain words

Thruster simulation codes currently need a hand-tuned correction factor for how easily electrons cross the magnetic field. A formula derived from physics would make the codes predictive.

Precise statement

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_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.

What would settle it

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

Status in the literature

Unverified note

3D particle-in-cell simulations in 2025-2026 resolve the electron drift instability and near-wall transport paths (e.g. arXiv:2603.14849), but no tuning-free closure exists.