End Loss and Plugging in Mirrors

Why open-ended mirrors leak, and how the tandem-mirror plug fixes it.

Problem

Open-end leakage

Solution

Ambipolar plug

Requirement

n_p/n_c 16

A simple magnetic mirror leaks plasma out its open ends. The tandem mirror solves this by placing dense, high-field plugs at each end whose electrostatic (ambipolar) potential repels escaping ions. Building that potential requires the plug to reach a density about 16× the central cell — the burner's binding requirement.

Understanding end loss is understanding both the burner's advantage (no disruptions, direct conversion) and its central gate.