# integral equations

## The Perspective Slow-wave Systems of Terahertz Band for TWT

In this paper the review of terahertz perspective slow-wave systems is presented for TWT.

The methods of modeling have been considered and some numerical results are presented.

## Integral Equations for Photonic Crystal Fibers

The integral and integrodifferential equations for photonic crystal waveguides (fibers) have been obtained both for finite and infinite dimensions of quasiperiodic dielectric coverings. Previously the equations for two-dimensional periodic photonic crystals with magnetodielectric and metallic periodic inclusions have been considered. The corresponding numerical results are presented.

## About the Definition of a Nonlinear Inductance in Static and Dynamic Regimes

The integral relations and integral-differential equations that take into account the influence of the magnetic shields (magnetic) inductance have been obtained. The non-linear magnetic materials with hysteresis and without it, and approximation of nonlinear materials and inductors have been considered. It is shown that for hysteresis we should use the nonlinear equation for the magnetization. The establishment of oscillations in a chain with the simplest approximation of a nonlinear inductance are reviewed.