Localization of electron modes in nonuniform helicon plasma

New guided electrostatic and electromagnetic modes propagating in a nonuniform magnetized plasma with plane geometry are presented. The modes may arise in a plasma with a region of strong inhomogeneity leading to a concentration of wave energy and, thus, a localization of the modes. These localized modes can only propagate if the density gradient is sufficiently strong, whereas they do not exist in weakly nonuniform plasma. The eigenfunctions and the spectrum of the modes are found. In detail, the properties of the modes are studied for particular profiles in the transitional layer between two uniform plane plasma regions.