A simple and fast model for numerically calculating small-signal gain in serpentine waveguide traveling-wave tubes (TWTs) is described. In the framework of Pierce model, we consider 1-D electron flow along a dispersive single-mode slow wave structure (SWS), accounting space-charge effect. The analytical accounts frequency-dependent phase velocity characteristic impedance obtained using various equivalent circuit models from literature, validated by comparison with full-wave eigenmode...

The interaction between a linear electron beam and guided electromagnetic wave is studied in the contest of exceptional points degeneracy (EPD) supported by such an interactive system. study focuses on case traveling tube (TWT) with realistic helix waveguide slow-wave structure (SWS). formulated analytical model that generalization Pierce model, assuming one-dimensional flow along dispersive single-mode guiding SWS taking into account space-charge effects augmented using phase velocity...

We present an analytical method to compute the wavenumbers and electric fields of space-charge-wave eigenmodes supported by a two-stream electron beam, consisting solid inner cylindrical stream coaxial outer annular stream, both contained within metallic tunnel. extend model developed Ramo case two streams. The accounts for interaction between streams with presence beam-tunnel wall; it can be used complex associated instability plasma frequency reduction effects in vacuum electronic...

We develop an analytical model for traveling wave tubes (TWTs) amplifiers based on the serpentine waveguide (SW). This is a generalization of Pierce model, assuming one-dimensional electron flow along dispersive slow-wave structure (SWS), with space-charge effects accounted for. The cold parameters, i.e., phase velocity and characteristic impedance, are in equivalent circuit model. use relation between interaction impedance extra correction factor that accounts non-uniform beam-wave over...

We introduce two novel variants of the serpentine waveguide (SWG) slow wave structure (SWS), often utilized in millimeter-wave traveling-wave tubes (TWTs), with enhanced interaction impedance. Using dispersion engineering conjunction transfer matrix methods, we tune guided wavenumber relation to exhibit stationary inflection points (SIPs), and also nonstationary, or "tilted" (TIPs), within dominant TE10 mode a rectangular waveguide. The degeneracy is found below first upper band edge...

We propose a scheme to calculate the reduced plasma frequency of cylindrical-shaped electron beam flowing inside cylindrical tunnel, based on results obtained from Particle-in-cell (PIC) simulations. In PIC simulations, we modulate using two parallel, non-intercepting, closely-spaced grids which are electrically connected together by single-tone sinusoidal voltage source. The energy and current distributions along length tunnel monitored after system is operating at steady-state. build...

We introduce a practical method for modeling the small-signal behavior of dispersive and inhomogeneous helix-type traveling-wave tube (TWT) amplifiers based on generalization one-dimensional Pierce model. Our model is applicable to both single-stage multi-stage TWTs. Like model, we assume that electrons flow linearly in one direction, parallel proximity slow-wave structure (SWS) which guides single dominant electromagnetic mode. Realistic helix TWTs are modeled with position dependent...

We introduce a practical method for modeling the small-signal behavior of frequency-dispersive and inhomogeneous helix-type traveling-wave tube (TWT) amplifiers based on generalization one-dimensional (1D) Pierce model. Our model is applicable to both single-stage multi-stage TWTs. Like model, we assume that electrons flow linearly in one direction, parallel proximity slow-wave structure (SWS) guides single dominant electromagnetic mode. Realistic helix TWTs are modeled with...

The dispersion of a three-way waveguide is engineered to exhibit exceptional modal characteristics. Two coupled waveguides with parity-time ($\mathcal{P}\mathcal{T}$) symmetry have been previously demonstrated second order points degeneracy (EPDs). In this work, we introduce and investigate particular class EPDs, applicable from radio frequency optical wavelengths, whereby three satisfy glide-time ($\mathcal{G}\mathcal{T}$) third real-valued wave number. $\mathcal{G}\mathcal{T}$ involves...

We introduce a new geometry for serpentine waveguide slow-wave structures (SWS) traveling-wave tubes (TWTs) with enhanced interaction impedance, or Pierce due to the stationary inflection point (SIP), i.e., frozen mode. The three-way geometry, ladder (SLWG), can be easily designed exhibit such SIPs within dominant TE10 mode of cross section, below first upper band-edge (SWG), where beam-wave synchronization typically occurs in SWG TWTs. These an impedance three-modes that are synchronized...

A simple and fast model for numerically calculating small-signal gain in serpentine waveguide traveling-wave tubes (TWTs) is described. In the framework of Pierce model, we consider one-dimensional electron flow along a dispersive single-mode slow-wave structure (SWS), accounting space-charge effect. The analytical accounts frequency-dependent phase velocity characteristic impedance obtained using various equivalent circuit models from literature, validated by comparison with full-wave...

Microfabricated traveling-wave tubes (TWTs) are often utilized for amplifying millimeter-wave signals to high power levels over broad bandwidths. One of the crucial components TWT which determines its bandwidth is periodic slow-wave structure (SWS) that velocity-synchronize and exchange energy between guided electromagnetic (EM) waves space-charge in a linear electron beam. Interestingly, many "space-harmonic" SWSs found literature, such as serpentine, coupled-cavity, staggered-vane have one...

We present the novel concept of exceptional points degeneracy (EPDs), which denote a coalescence multiple eigenmodes, that directly emerge in systems when linear time-periodic (LTP) variation is applied. Though presented theory general, as an example we establish general conditions yield EPD single LTP LC resonator with capacitance varies periodically time. show potential application proposed system making sensors to exploit ultra-sensitivity associated operating at EPD.

We propose a scheme to calculate the reduced plasma frequency of cylindrical-shaped electron beam flowing inside cylindrical tunnel, based on results obtained from Particle-in-cell (PIC) simulations. In PIC simulations, we modulate using two parallel, non-intercepting, closely-spaced grids which are electrically connected together by single-tone sinusoidal voltage source. The energy and current distributions along length tunnel monitored after system is operating at steady-state. build...

A microstrip-technology three-way waveguide has been conceived to display exceptional modal degeneracy in the presence of periodic gain and radiation losses satisfying parity-time ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$PT$</tex> ) glide-symmetry. third order point (EPD) is obtained dispersion relation, where three Floquet-Bloch eigenmodes coalesce at a single frequency, their eigenvalues polarization states. In proposed structure,...

We present an analytical method to compute the wavenumbers and electric fields of space-charge-wave eigenmodes supported by a two-stream electron beam, consisting solid inner cylindrical stream coaxial outer annular stream, both contained within metallic tunnel.We extend model developed Ramo case two streams. The accounts for interaction between streams with presence beam-tunnel wall; it can be used complex associated instability plasma frequency reduction effects in vacuum electronic...

An analytical model for the interaction between a linear electron beam and realistic helix slow-wave structure (SWS) in traveling wave tube (TWT) is provided. It generalization of Pierce interaction, assuming <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$a$</tex> one-dimensional flow along dispersive SWS, with space-charge effects accounted for. The used phase velocity characteristic impedance are extracted from full-wave simulations....