Mirror Ratio

The field-strength ratio between a mirror's throat and its centre; it sets how well particles are trapped.

In a magnetic mirror, the field is stronger at the ends ('throats') than in the middle. The mirror ratio — throat field over central field — determines the range of particle velocities that are reflected and confined.

The Kronos burner uses high-field plug coils (throat field 17 T, plug/ion-end 26.49 T) to raise the effective mirror ratio and, with an ambipolar potential, plug the ends.