THE THEORETICAL INVESTIGATION OF THz ELECTROMAGNETIC WAVES IN A ROD DEGENERATE PLASMA-WAVEGUIDE

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.…”

“…The intersections of the space charge wave with different modes are considered to be the eigenfrequencies of the device. 12,21 In Figs. 3-6, only TM 03 mode is taken into account.…”

“…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.…”

“…In addition, the Cerenkov instability can bunch the electron beam and generate microwave radiation when a dielectric-lined waveguide is used as a resonant slow-wave structure, driven by a relativistic electron beam. [11][12][13][14] The Cherenkov instability for microwave generation in plasma Cherenkov masers and the principles of plasma relativistic microwave electronics were demonstrated by Kuzelev et al 15,16 Also the dispersion relation of electromagnetic waves in a cylindrical metallic waveguide with unmagnetized 12 and magnetized 17 degenerate plasma columns protected by annular dielectric layers was investigated. In the aforementioned works, the investigated cylindrical metallic waveguides had smooth walls.…”