One method for confining hot plasma is to arrange electric coils so as to make a mirror machine in which the magnetic field has the geometry sketched in Fig. 20.6a. Suppose that the magnetic field in the center is 1T and the field strength at the two necks is 10T, and that plasma is introduced with an isotropic velocity distribution near the center of the bottle.

(a) What fraction of the plasma particles will escape?

(b) Sketch the pitch-angle distribution function for the particles that remain.

(c) Suppose that Coulomb collisions cause particles to diffuse in pitch angle α with a diffusion coefficient

Estimate how long it will take most of the plasma to escape the mirror machine.

(d) What do you suspect will happen in practice?

Figure 20.6a.

Transcribed Image Text:

Daa = Δαξι ΔΙ (20.59)