High-powered microwave devices are designed to transfer energy to targets via ultra-high-frequency radio waves, in civil applications, such as radar and communication systems, heating and current drive of plasmas in fusion devices, and acceleration in high-energy linear colliders.

They can also be used for military purpose in directed-energy weapons or missile guidance systems. 

To generate such high-power microwaves, researchers rely on backward wave oscillators, which are designed to transform the energy of an intense electron beam into electromagnetic radiation at microwave frequencies - basically they convert DC power into RF power and up. The electron beam propagates axially through a slow wave structure to excite RF power. The slow electro-dynamic structure is designed to slow down the electromagnetic wave to phase velocities less than the speed of light so that the wave interact with the electron beam in a resonant manner. This interaction, in turn, leads to an instability, which is the prerequisite for energy transfer from the electron beam to the electromagnetic wave, and for turning it into high-power microwaves.

Metallic cylinders with a sinusoidally shaped, periodically corrugated inner wall are being extensively used as slow electro-dynamic structures. The trouble is that they are difficult to manufacture, and require sophisticated numerical machines to design. To overcome this issue, the authors propose an alternative shape of the slow electro-dynamic structure, in the form of a novel semi-circular structure.

They employ numerical techniques to model the dynamics of this structure, and prove that it is a viable alternative for generating high-power microwaves.

Citation: Md. G. Saber, R.H. Sagor and Md. R. Amin (2015), Numerical Study of the Dispersion Characteristics of a Semi-Circularly Corrugated Slow Wave Structure, European Physical Journal D 69: 38, DOI: 10.1140/epjd/e2014-50798-5