Results of theoretical and experimental studies of a GW-class, large diameter microwave oscillator are presented. The device consists of a large cross-section (overmoded), slow-wave structure with a unique profile of wall radius specifically designed to support surface waves and to provide a strong beam-wave coupling at moderate voltage (500 kV), an internal adjustable microwave reflector, a co...

We describe results from the initial operation of our coaxial gyroklystron experiment, which is being evaluated as a potential driver for future linear colliders. The interaction is designed to occur between a 500 kV, 500 700 A beam and a series of coaxial TE0n1 microwave cavities. Output powers in excess of 100 MW at 8.568 GHz are expected with an efficiency of about 40% [1]. We detail perform...

We have carried out detailed investigations on the light absorption mechanism in single crystalline silicon (c-Si) (core)/amorphous Si (a-Si) (shell) coaxial nanowires (NWs). Based on the Lorenz-Mie light scattering theory, we have found that the light absorption in the coaxial NWs relies on the leaky mode resonances and that the light absorption can be optimized towards photovoltaic applicatio...

In order to realize a single-layer corporate-fed slot array, a hollow rectangular coaxial line is adopted as a feeding line. A 2×2-element subarray on a hollow rectangular coaxial line for the corporate-fed array is designed for the 60-GHz band. For the wideband operation, a cavity-backed wide slot is adopted as a radiating element. The 5.7% bandwidth for the reflection less than −20 dB is obta...

We theoretically show that coaxial waveguides composed of a metallic core, surrounded by a dielectric cylinder and clad by a metal outer layer exhibit negative refractive index modes over a broad spectral range in the visible. For narrow dielectric gaps (10 nm GaP embedded in Ag) a figure-of-merit of 18 can be achieved at lambda(0) = 460 nm. For larger dielectric gaps the negative index spectra...

We present a drilling method that is based on the phenomenon of local hot spot generation by near-field microwave radiation. The microwave drill is implemented by a coaxial near-field radiator fed by a conventional microwave source. The near-field radiator induces the microwave energy into a small volume in the drilled material under its surface, and a hot spot evolves in a rapid thermal-runawa...

Objects rotating in depth with an ambiguous rotation direction frequently appear to rotate together. Corotation is especially strong when the objects are interpretable as having a shared axis. We manipulated the initial conditions of the experiment by having pairs of objects initially appear to be unambiguous, and then make either a sudden or gradual transition to ambiguous spin. We find that i...

Interfaces between a coaxial structure and a post-wall waveguide are proposed as the essential components for cost-effective millimeter-wave modules. PTFE substrate is selected in terms of loss and manufacturability. The reflection and the transmission characteristics are investigated. The short-stepped and the short-taper-stepped feeding structures provide 14.7% and 13.2% bandwidths for the re...

This paper describes efforts undertaken to upgrade ac-dc current transfer standards and calibrations at the National Research Council of Canada. The ac-dc current transfer comparator has been redesigned, using guarding techniques most advantageous for the current shunt comparisons. A set of coaxial shunts for currents between 10 mA and 10 A has been built, and characterized up to 100 kHz by a s...

Experiment and simulation demonstrate high power microwave generation at 9 GHz using a 9-cm-diam, 44%keV, 7-kA annular electron beam. The beam is propagated in a coaxial drift tube between inner and outer conductors, a configuration which increases the available beam current and reduces the surface fields from existing high power sources. The microwave interaction is provided by an extended len...