Excitation of terahertz plasmons eigenmode of a parallel plane guiding system by an electron beam

Abstract

Two parallel semiconductor plates, separated by a short distance, support surface plasmon eigenmode with amplitude maxima at the inner surfaces of the plates and minimum at the center. A relativistic sheet electron beam propagating through the space between the planes resonantly excites the surface plasma wave (SPW). The frequency of the driven SPW decreases with the energy of the beam while the growth rate increases. At the beam current ≈168 A the growth rate of 5.93×108 rad/s is achieved at the frequency ≈0.51 THz of SPW for the 5 mm ŷ width and spacing between the two plates of ≈2.83 mm. The growth rate scales as 1/3 root of the electron beam current.