Electron-Acoustic Waves with Orbital Angular Momentum

Abstract

The c!cctron-ncouctic (EA) waves carrying orbital angular momentum arc investigated in a coUisioniess, unmagnetized uniform plasma. The latter is basically a two-temperat.ure electron plasma composed of two populat.ions of elecLrons, e.g. the inertial cold electrons and the Boltzmann distribut.ed hot electrons with a neuLralizing background of static ions. By employing the fluid equations, the dispersion relation for the EA waves is solved for a beam type solution under the paraxial approximat.ion and also discussed the Laguerre-Gaussian (LC) solutions. An approximate solution for t.he electrostat.ic potential problem is obtained and the electric field components are now expressed ill terms of LG potential representing the field lines as heUcal structures. F\lrthermore, t.he energy Aux and orbital angular moment.um states carried by the EA beam are studied in terms of LG potential perturbations. Numerically, it is revealed that the radial and angu lar mode indices strongly modify the profiles of the LG potential. The present results are important in the context of trapping and transporting the plasma part.icles and energy by the EA beams involving the orbital angular momentum states in laser produced plasma as well as in space plasmas, where two distinct populations of electrons exist.