High-Power Terahertz-Range Planar Gyrotrons with Transverse Energy Extraction

Abstract

To increase the output power of terahertz gyrotrons to several hundred kilowatts, we suggest using a planar geometry of interaction space with a sheet electron beam and transverse energy extraction. An advantage of this scheme in comparison with conventional cylindrical geometry is the possibility to ensure effective mode selection over the open transverse coordinate in combination with radiation outcoupling that leads to a substantial reduction of Ohmic losses. Similar to unstable resonators in optics for further growth of the radiation power it is beneficial to introduce waveguide tapering.

High-field half-cycle terahertz radiation from relativistic laser interaction with thin solid targets

“…Via coherent transition radiation (CTR), high field THz radiation with ultrashort electron bunches from Linac has been reported [9,10,11]. In principle, the ultrashort intense laser pulses can also generate ultrashort electron bunches, which can be used to produce intense THz emission through CTR.…”

Simulations of powerful microwave oscillators with oversized electrodynamics systems

“…To increase output power of terahertz gyrotrons to several hundred kilowatts, we suggest using a planar geometry of interaction space with a sheet electron beam and transverse energy extraction [3]. An advantage of this scheme in comparison with conventional cylindrical geometry is the possibility to ensure effective mode selection over the open transverse coordinate in combination with radiation outcoupling that leads to a substantial reduction of Ohmic losses.…”

“…In this report we consider terahertz-band gyrotrons with conventional cylindrical and planar configurations of the interaction space [1][2][3]. Here we discuss generators operating at the fundamental harmonic, as well as at the second and third harmonics.…”

Photonic-Band-Gap Traveling-Wave Gyrotron Amplifier

“…The Doppler shifted electron beam resonance condition is given by $$\omega -s\mathrm{normal\Omega }⁄\gamma -k_z{\upsilon }_z=0$$and the waveguide mode dispersion relation is $${\omega }^2-k_z^2{c}^2-k_{\perp }^2{c}^2=0,$$where ω is the frequency of the wave; Ω = eB 0 / m e is the nonrelativistic cyclotron frequency; e and m e are, respectively, the charge and the rest mass of the electron; γ = (1 − υ 2 / c 2 ) −1/2 is the relativistic mass factor; υ is the electron velocity; s = 1 is the cyclotron harmonic number; k z and k ┴ are the longitudinal and transverse propagation constants, respectively, of the waveguide mode; υ z is the axial velocity of the electrons, and c is the speed of light. The uncoupled dispersion relations of the cyclotron resonance mode, (1), and a TE waveguide mode, (2), for a typical operating point are shown in Fig. 1.…”

“…The coupled dispersion relation of the amplified wave, which propagates as $e^{ikfalse(\mathrm{normal\Gamma }-\overline{\mathrm{\Delta }}false)z}$, resulting from the interaction between the electron beam and the electromagnetic mode is given by $${\mathrm{\Gamma }}^{2}false(\mathrm{normal\Gamma }-\overline{\mathrm{\Delta }}false)+\overline{\mu }{I}_0^{\prime }=0,$$where β = υ / c , k = ω / c , $\overline{\mathrm{\Delta }}=false(1⁄{\beta }_{z0}false)-false(s\mathrm{normal\Omega }⁄{\beta }_{z0}{\gamma }_0\omega false)-false(k_z⁄kfalse)$, $\overline{\mu }=false({\beta }_{\perp 0}^2⁄2{\beta }_{z0}false)false(1-{false(k_z⁄kfalse)}^{2}false)⁄false(1-k_z⁄kfalse){\beta }_{z0}false)$, k z is determined from (2) $I_0^{\prime }$ is the normalized current given in [23], and a small term linear in Γ has been omitted. Equation (3) has three roots corresponding to a growing wave, a damped wave, and an unperturbed wave.…”