Excitation of THz symmetric TM-modes in a cylindrical metallic waveguide with an axial magnetized degenerate plasma rod by an electron beam

Waveguide modes in a relativistic electron beam with an axial magnetic field

“…The influence of magnetic field on a system of two counter-propagating electron beams has been investigated by computer simulation and it has been confirmed that a sufficiently strong magnetic field suppresses the filamentation instability [11]. Dispersion relation (DR) of transverse magnetic (TM) waveguide modes in background plasma is obtained in [12]. DR of waveguide modes in an REB moving through a plasma-filled waveguide has been derived in [13].…”

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

“…12,17 In this case, the dispersion relation for real values of the wave number has a complex frequency solution.…”

“…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…”

“…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.…”