A method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations. We present results of a measurement of such an arrangement at Brookhaven’s Accelerator Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-t...

We demonstrate how micromachined photonic crystals can be used to negatively refract terahertz frequency light. The photonic crystals, which are constructed from conventional dielectric materials, manipulate the incident beam via interaction with their photonic bands. Consequently, we show that different components of a broadband beam incident on the structure may be positively or negatively re...

this paper deals with volume fraction optimization of functionally graded (fg) beams resting on elastic foundation for maximizing the first natural frequency. the two-constituent functionally graded beam consists of ceramic and metal. these constituents are graded through the thickness of beam according to a generalized power-law distribution. one of the advantages of using generalized power- l...

Great hopes rest on surface plasmon polaritons' (SPPs) potential to bring new functionalities and applications into various branches of optics. In this paper, we demonstrate a pin cushion structure capable of coupling light from free space into SPPs, split them based on the polarization content of the illuminating beam of light, and focus them into small spots. We also show that for a circularl...

Experimental work is planned to study the performance of a beam-driven cylindrical dielectric wakefield accelerating structure as a source of THz coherent Cerenkov radiation (CCR). For an appropriate choice of dielectric tube geometry and driving electron bunch parameters, the device operates in a single-mode regime, producing radiation in the THz range. This source can potentially produce high...

The Proof-of-Principle (POP) prototype of the Rf-Focused Drift tube (RFD) linac structure is currently under test at Linac Systems, after years of delay due to a variety of technical problems. A discussion of these technical problems and their solutions will be presented. The status of these tests will be reported. Plans for future development of this linac structure will be revealed. Potential...

The microstructure of nominally undoped epitaxial wurtzite-structure o-GaN films, grown by gas-source molecular-beam epitaxy, plasma-assisted molecular-beam epitaxy, and metalorganic chemical-vapor deposition, has been investigated by transmission electron microscopy (TEM) and high-resolution TEM. The results show that undoped a-GaN films have an ordered point-defect structure. A model of this ...

The main purpose of this article is the structural analysis of a composite blade of a selected helicopter. In this study, the stresses on rotors' blades caused by centrifugal forces, lift, drag and torque are analyzed. The governing equations of the structure behavior and solving processes were carried out by MATLAB software, and simulation is carried out by ABAQUS software, and they are compar...

Size-dependent vibrational and instability behavior of fluid-conveying magneto-electro-elastic (MEE) tubular nano-beam subjected to magneto-electric potential and thermal field has been analyzed in this study. Considering the fluid-conveying nanotube as an Euler-Bernoulli beam, fluid-structure interaction (FSI) equations are derived by using non-classical constitutive relations for MEE material...