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Register a new userMolybdenum sputtering film characterization for high gradient accelerating structures
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Technological advancements are strongly required to fulfill the demands of new accelerator devices with the highest accelerating gradients and operation reliability for the future colliders. To this purpose an extensive R&D regarding molybdenum coatings on copper is in progress. In this contribution we describe chemical composition, deposition quality and resistivity properties of different molybdenum coatings obtained via sputtering. The deposited films are thick metallic disorder layers with different resistivity values above and below the molibdenum dioxide reference value. Chemical and electrical properties of these sputtered coatings have been characterized by Rutherford backscattering, XANES and photoemission spectroscopy. We will also present a three cells standing wave section coated by a molybdenum layer $sim$ 500 nm thick designed to improve the performance of X-Band accelerating systems.
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MPC (Magneto-Photonic Crystal) Optimisation is a feature-rich Windows software application designed to enable researchers to analyze the optical and magneto-optical spectral properties of multilayers containing gyrotropic constituents. A set of computational algorithms aimed at enabling the design optimization and optical or magneto-optical (MO) spectral analysis of 1D magnetic photonic crystals (MPC) is reported, together with its Windows software implementation. Relevant material property datasets (e.g., the optical spectra of refractive index, absorption, and gyration) of several important optical and MO materials are included, enabling easy reproduction of the previously published results from the field of MPC-based Faraday rotator development, and an effective demonstration-quality introduction of future users to the multiple features of this package. We also report on the methods and algorithms used to obtain the absorption coefficient spectral dispersion datasets for new materials, for which the film thickness, transmission spectrum, and refractive index dispersion function are known.
High throughput experimental methods are known to accelerate the rate of research, development, and deployment of electronic materials. For example, thin films with lateral gradients in composition, thickness, or other parameters have been used alongside spatially-resolved characterization to assess how various physical factors affect material properties under varying measurement conditions. Similarly, multi-layer electronic devices that contain such graded thin films as one or more of their layers can also be characterized spatially in order to optimize the performance. In this work, we apply these high throughput experimental methods to thin film transistors (TFTs), demonstrating combinatorial device fabrication and semi-automated characterization using sputtered Indium-Gallium-Zinc-Oxide (IGZO) TFTs as a case study. We show that both extrinsic and intrinsic types of device gradients can be generated in a TFT library, such as channel thickness and length, channel cation compositions, and oxygen atmosphere during deposition. We also present a semi-automated method to measure the 44 devices fabricated on a 50x50mm substrate that can help to identify properly functioning TFTs in the library and finish the measurement in a short time. Finally, we propose a fully automated characterization system for similar TFT libraries, which can be coupled with high throughput data analysis. These results demonstrate that high throughput methods can accelerate the investigation of TFTs and other electronic devices.
Two standing-wave single-cell choke-mode damped structures with different choke dimensions which worked at 11.424 GHz were designed, manufactured and tuned by accelerator group in Tsinghua University. High power test was carried out to study choke-mode structures properties in high gradient and related breakdown phenomenon. A single-cell structure without choke which almost has the same inner dimension as choke-mode structure was also tested as a comparison to study how the choke affects high-gradient properties. In this paper, we report on the latest status of the high power test, including various observations and the experimental results.
Very recently, it has been shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor [1]. We will present here the preparation and characterization of graphitic carbon nitride (g-C3N4) films on semiconducting substrates by thermal condensation of dicyandiamide precursor under inert gas conditions. Structural and surface morphological studies of the carbon nitride films suggest a high porosity of g-C3N4 thin film consisting of a network of nanocrystallites. Photo-electrochemical investigations show upon cathodic polarization light-induced hydrogen evolution for a wide range of proton concentrations in the aqueous electrolyte. Additionally, Synchrotron radiation based photoelectron spectroscopy has been applied to study the surface/near-surface chemical composition of the utilized g-C3N4 film photocathodes. For the first time it is shown that g-C3N4 films can be successfully applied as photoelectrochemical material for light induced hydrogen evolution. [1]X. Wang, K. Maeda, A. Thomas, K. Takanabe, G. Xin, J. M. Carlsson, K. Domen, M. Antonietti, Nature Mat. 2009, 8, 76-80.
The cw CCL being designed for the Accelerator Production of Tritium (APT) project accelerates protons from 96MeV to 211MeV. It consists of 99 segments each containing up to seven accelerating cavities. Segments are coupled by intersegment coupling cavities and grouped into supermodules. The design method needs to address not only basic cavity sizing for a given coupling and pi/2 mode frequency, but also the effects of high power densities on the cavity frequency, mechanical stresses, and the structures stop band during operation. On the APT project, 3-D RF (Ansoft Corp.s HFSS) and coupled RF/structural (Ansys Inc.s ANSYS) codes are being used to develop tools to address the above issues and guide cooling channel design. The codes predictions are being checked against available low power Aluminum models. Stop band behavior under power will be checked once the tools are extended to CCDTL structures that have been tested at high power. A summary of calculations made to date and agreement with measured results will be presented.
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