The direct detection of gravitational waves (GWs) of frequencies above MHz has recently received considerable attention. In this work, we present a precise study of the reach of a cubic cavity ...resonator to GWs in the microwave range, using for the first time tools allowing to perform realistic simulations. Concretely, the boundary integral—resonant mode expansion (BI-RME) 3D method, which allows us to obtain not only the detected power but also the detected voltage (magnitude and phase), is used here. After analyzing three cubic cavities for different frequencies and working simultaneously with three different degenerate modes at each cavity, we conclude that the sensitivity of the experiment is strongly dependent on the polarization and incidence angle of the GW. The presented experiment can reach sensitivities up to 1 × 10 − 19 at 100 MHz, 2 × 10 − 20 at 1 GHz, and 6 × 10 − 19 at 10 GHz for optimal angles and polarizations, and where in all cases we assumed an integration time of Δ t = 1 ms . These results provide a strong case for further developing the use of cavities to detect GWs. Moreover, the possibility of analyzing the detected voltage (magnitude and phase) opens a new interferometric detection scheme based on the combination of the detected signals from multiple cavities. Published by the American Physical Society 2024
In this paper, we present an efficient and rigorous method, based on the 3-D boundary integral-resonant-mode expansion technique, for the analysis of multiport rectangular waveguide junctions ...compensated with partial-height cylindrical metallic posts. The electrical performance of a great variety of commonly used wideband microwave circuits has been improved drastically thanks to the introduction of a new design parameter, i.e., the relative position of the metallic post in the structure. To the authors' knowledge, this parameter has not been taken into account in previous studies concerning compensated junctions using partial-height metallic posts. The developed tool has been successfully used to design compensated H- and E-plane right-angled bends and power dividers, as well as optimal magic-T junctions. This novel tool has been fully verified through comparisons between our results and those provided by a well-known commercial finite-element method software
Data on dermal penetration of nanoparticles (NPs) was reviewed with the goal to establish a worst-case dermal penetration value for NPs. To this aim, the main focus was on studies providing ...quantitative dermal penetration data (29 studies). In vivo dermal penetration studies and ex vivo studies based on skin explants were included. These studies used NPs with different compositions, dimensions, and shapes. The overall results showed that skin is an efficient barrier for NPs, indistinctly of their properties. However, some studies reported that a small percentage of the applied NP dose penetrated the skin surface and reached deeper skin layers. The integrity of the skin layer and the product formulation were more critical determinants of dermal penetration than the NP properties. Most quantitative studies were based on elemental analysis such that it cannot be concluded if detected levels are attributable to a dissolved fraction or to the penetration of particles as such. Results of qualitative imaging studies suggest that at least a fraction of the levels reported in quantitative studies could be due to particle penetration. Altogether, based on the data compiled, we propose that 1% could be used as a worst-case dermal penetration value for nanoparticles within the boundaries of the properties of those included in our analysis.
•Variations in test design along with NP properties, hindered interstudy comparisons.•A trend towards lower dermal penetration with increasing size was observed.•No clear conclusions can be derived on the role of shape or coating.•Existing studies probably overestimate dermal penetration of NPs in their particulate form.•The worst-case dermal penetration value in healthy skin was 1% of the applied dose.
This paper presents a study of the multipactor effect in a partially dielectric-loaded rectangular waveguide. To obtain the simulations presented in this paper, a detailed analysis of the dynamics of ...the electron inside this waveguide has been performed, taking into account the radio frequency electromagnetic fields propagating in the waveguide and the dc electric field that appears because of the charging of the dielectric layer. This electrostatic field is obtained by computing the electric potential produced by an arbitrary charge distribution on the dielectric layer in a dielectric-loaded waveguide. The electron trajectory is then found by numerically solving the equations of motion. The results obtained show that multipactor discharges do turn off by themselves under certain circumstances when they occur in such dielectric-loaded waveguide.
This letter presents the experimental study of the multipactor threshold in a partially dielectric-loaded rectangular waveguide, whose results validate a multipactor model recently developed by the ...authors, which includes the charge distribution appearing on the dielectric surface during the multipactor discharge. First, the variation of the multipactor RF voltage threshold has been theoretically analyzed in different waveguide configurations: in an empty waveguide, and also in the cases of a one-sided and two-sided dielectric-loaded waveguides. To reach this aim, an in-house Monte Carlo simulation tool has been developed. The Secondary Electron Yield (SEY) of the metallic and dielectric materials used in the numerical simulations have been measured experimentally. Finally, an aluminum WR-75 symmetric <inline-formula> <tex-math notation="LaTeX">E </tex-math></inline-formula>-plane rectangular waveguide transformer has been designed and fabricated, in which several multipaction tests have been carried out to validate the in-house software tool, demonstrating an excellent agreement between the simulation results and the experimental data.
Wedge-shaped waveguides present a certain advantage with respect to rectangular waveguides regarding their resistance to multipactor discharges. In this paper, the optimal configuration for the wedge ...geometry is investigated based on theoretical results, on a precise multipactor prediction tool, and on previous experience. In addition, design rules are presented, which allow us to achieve for wedge-shaped filters electrical performances comparable to the ones of rectangular waveguide filters, while at the same time improving the multipactor-free power range. As a proof of concept, two three-pole bandpass filters with equivalent electrical characteristic of 150-MHz bandwidth, centered at 12 GHz (Ku band), and the same Q factor have been designed, manufactured, and tested. The first design is based on conventional rectangular waveguide technology, while the second one has non-parallel broadside walls (wedge-shaped cross section). The multipactor power threshold and RF performance of the filters have been measured in order to validate the improvements achievable employing wedge-shaped resonators.
Whispering-gallery modes resonances of submicron wall thickness capillaries exhibit very large wavelength shifts as a function of the refractive index of the medium that fills the inside. The ...sensitivity to refractive index changes is larger than in other optical microcavities as microspheres, microdisks and microrings. The outer surface where total internal reflection takes place remains always in air, enabling the measure of refractive index values higher than the refractive index of the capillary material. The fabrication of capillaries with submicron wall thickness has required the development of a specific technique. A refractometer with a response higher than 390 nm per refractive index unit is demonstrated. These sensors are readily compatible with microfluidic systems.
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