Studies of Nanotube Channeling for Efficient Beam Scraping at Accelerators

While particle beam steering (and in particular, "scraping") in accelerators by bent channeling crystals is an established technique extensively tested at IHEP Protvino and other major high-energy labs, an interesting question is how one could improve channeling capabilities by applying modern nanotechnology. Theoretical research of nanotube channeling was in progress over recent years. In this work, we assess potential benefits from nanotube channeling for real accelerator systems. We report simulation studies of channeling in nanostructured material (carbon SWNT and MWNT) tested for possible serving as a primary scraper for the collimation systems of hadron colliders. The advantages of nanostructured material as a potential choice for a primary scraper in a high-energy accelerator such as LHC or the Tevatron are discussed in comparison to crystal lattices and amorphous material. We evaluate physical processes relevant to this application and reveal nanotechnology requirements.Comment: Presented at the Int. Conf. on Atomic Collisions with Solids (ICACS-21, Genova 4-9 July 2004

Short Circuit Current Contribution for Different Wind Turbine Generator Types: Preprint

This paper presents simulation results for short-circuit current contribution for different types of WTGs obtained through transient analysis using generic WTG models

Electromagnetic field and radiation for a charge moving along a helical trajectory inside a waveguide with dielectric filling

We investigate the electromagnetic field generated by a point charge moving along a helical trajectory inside a circular waveguide with conducting walls filled by homogeneous dielectric. The parts corresponding to the radiation field are separated and the formulae for the radiation intensity are derived for both TE and TM waves. It is shown that the main part of the radiated quanta is emitted in the form of the TE waves. Various limiting cases are considered. The results of the numerical calculations show that the insertion of the waveguide provides an additional mechanism for tuning the characteristics of the emitted radiation by choosing the parameters of the waveguide and filling medium.Comment: 17 pages, 9 figures, discussion, graphs, and references adde

Wind Resource Development Project for Armenia

Armenia has few proven reserves of natural energy and is dependent on long, unreliable transport lines for oil and gas. Preliminary studies indicate that the wind energy potential in Armenia is more than 500 megawatts (MW), assuming a reasonable fraction of 10% of the land area in the high-wind zones. Over the long term, the Armenian government intends to meet 8%--10% of its electric consumption needs by grid-connected wind turbines. The goals of this project are to enhance Armenia's energy security, mitigate the environmental damage of conventional sources of energy, reduce future carbon dioxide emissions, build an environmentally sound and sustainable model for economic development, and promote trade between the U.S. and Armenia. The project is being funded by the Cafesjian Family Foundation, a private foundation based in the United States in Naples, Florida, with the participation of Ecotrade, Inc. of Glendale, California. The National Renewable Energy Laboratory (NREL) is providing technical assistance. As part of the wind energy development project, the authors conducted a preliminary wind-energy resource assessment for some regions in Armenia. This activity provided valuable information needed to facilitate the commercialization of wind farms in Armenia and to lay the groundwork for subsequent wind resource activities. This paper presents the wind resource monitoring results (1999--2000) for the candidate site. Preliminary assessment identified areas with good-to-excellent wind resource potential

Complementary split-ring resonator-coupled traveling wave accelerating structure

In this paper, we present theoretical and simulation-based analyses of a novel, normal-conducting, multiple-cell, traveling wave accelerating structure. Instead of the conventional circular apertures, we utilize asymmetric complementary split-ring resonators to couple pillbox cavities and bring the phase velocity below that of the speed of light in vacuo. We show that this architecture exhibits a low, negative, group velocity and that the 0 through π modes decrease in order of frequency—in contrast to conventional electrically coupled structures in which the 0 mode has the lowest frequency and the π mode the highest. We illustrate the efficacy of the proposed design via electromagnetic and particle simulation results for a four-cell structure operating around 1.9 GHz. Results are given for operation in the π, 2π/3, and π/3 modes. Our design achieves accelerating gradients of around 3.3  MV/m and a cavity voltage of 0.594 MV for an applied rf power of 82 kW (π mode). The accelerating gradients achieved are up to 3.3 times that of a conventional circular aperture-coupled design with the same phase velocity, rf excitation power, operating frequency, mode type, and number of cells

Small Wind Turbine Testing and Applications Development

Small wind turbines offer a promising alternative for many remote electrical uses where there is a good wind resource. The National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory helps further the role that small turbines can play in supplying remote power needs. The NWTC tests and develops new applications for small turbines. The NWTC also develops components used in conjunction with wind turbines for various applications. This paper describes wind energy research at the NWTC for applications including battery charging stations, water desalination/purification, and health clinics. Development of data acquisition systems and tests on small turbines are also described

Line capacitance and impedance of coplanar-strip waveguides on substrates with multiple dielectric layers

Closed form formulas for the basic parameters of Coplanar-Strip line on a finite thickness substrate are reviewed. New, improved formulas are derived using conformal mapping technique

A Simple Parallel-Plate Resonator Technique for Microwave. Characterization of Thin Resistive Films

A parallel-plate resonator method is proposed for non-destructive characterisation of resistive films used in microwave integrated circuits. A slot made in one of the plates is used to measure surface impedance of a reference film and film under test. The surface impedance of the film under test is extract from these two measurements using a simple procedure. X-band experimental verification is given for a number of resistive films