Generation and amplification of terahertz electromagnetic waves in a plasma waveguide with a dielectric rod and an annular degenerate plasma

The dispersion relation and excitation of transverse magnetic mode electromagnetic waves in rippled-wall waveguide with a plasma rod and an annular dielectric

“…For an optimized particle-wave interaction, the electric field component of the wave and the directed motion of the relativistic electron beam must be parallel. 5,[22][23][24] Therefore, we will only investigate the dispersion characteristic of TM electromagnetic slow-waves in this configuration. According to Floquet's theorem, the longitudinal components of the field in the infinitely long metallic cylinder with an arbitrary periodic boundary take the following forms: 5,10,21…”

“…Here, B 0 n , C 0 n , D 0 n , and F 0 n are defined in Eqs. (19)- (22) and also E 0 n , G 0 n , H 0 n , and L 0 n are obtained as follows:…”

“…3-6, which essentially depends on the beam-plasma configuration in this geometry. 12,17,22 In these figures, the growth rate g is normalized by c=R 0 , and k z is normalized by 1=R 0 . Figure 8 represents the variations of growth rate versus the wave number k z for the operating frequency x r ¼ k z v 0 for two different dielectric radii.…”

“…Threshold for the emission occurs when the electron velocity is greater than the speed of light in the dielectric. 12,17,22 The frequency is determined by the synchronism between the electron velocity and the phase velocity of the driven mode. 12,17,22,26 For a electron beam with plasma frequency x b ¼ ð4pn b e 2 =m 0 Þ 1=2 and velocity v 0 propagating along the symmetric axis of the traveling wave tube, the dielectric tensor in cylindrical coordinates has the following form: 5,10ẽ where…”

Electromagnetic waves in uniaxial anisotropic chiral waveguides in magnetized plasma

“…Conceiving plasma as a guiding media in optical waveguides can modify the characteristics of the propagating electromagnetic waves. [26][27][28][29] The investigation of such a waveguide seems very insistent because applications of such a waveguide in engineering assume a comprehensive knowledge of the properties of its eigenmodes.…”