Numerical AGE for nearly infinite number and moderate depth of magnetic mirrors: (a) radial profile of plasma density; (b) analytical and numerical dispersion relations for uniform magnetic field; (c) axial profiles of periodic magnetic field with local defect (solid line) and typically formed AGE (dashed line) for x = 0.626, together with the decay constant (dotted) from Eq. (18), and (d) surface plot of the formed AGE (on axis) as a function of z and x. The RF antenna is labeled in the red thick line.