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Modeling, Fabrication, And Optimization Of Niobium Cavities Phase Iii: Quarterly Report, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

This quarterly report provides an update to the last phase of the Modeling, Fabrication, and Optimization of Niobium Cavities. Designing the experimental setup of secondary electron emission was well underway in early summer of 2003 when funding was made available for this portion the study. By March 2004, many of the components of the experimental study reached UNLV with some assembly accomplished. The first secondary electron emission (SEE) measurement was made from the surface of a Faraday cup in September 2004. At a particular beam energy, the current measured with the Faraday cup and electrometer changed sign over a range …

Study Of Ceramic Slurries For Investment Casting With Ice Patterns, Qingbin Liu, Ming-Chuan Leu, Harish Jose, Von Richards

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Ice patterns generated by rapid freeze prototyping or a molding process can be used to make ceramic investment molds for metal castings. Due to the use of ice, the ceramic slurries must be poured around the pattern and cured at sub-freezing temperatures. Success of this process depends greatly on the mold strength after the gelation of the slurries. This paper describes the experimental results of the mold strength after the gelation of the slurries under different compositions. The parameters considered include mixing time, alumino-silicate vs. fused silica ratio, volume of binder, and volume of catalyst. The strength of the gelled …

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements, Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this collaborative research project involving the University of Nevada Las Vegas (UNLV) and Idaho State University (ISU) is to evaluate the feasibility of determining residual stresses of welded, bent (three-point-bend), and cold-worked engineering materials using a new nondestructive technique based on positron annihilation spectroscopy (PAS). The proposed technique is to use γ-rays from a small MeV electron linear accelerator (Linac) to generate positrons inside the test sample via 2 pair production. This method can be used for materials characterization and investigation of defects in thick samples that usually cannot be accomplished by conventional positron technique or other …

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Iii Third Quarterly Report, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. The third phase concludes the experimental a fluid flow study and optimization study. The first quarter and second quarter of phase three also begins the experimental set-up of secondary emission studies from niobium in superconducting mode. This …

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Iii Second Quarterly Report, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. The third phase concludes the experimental a fluid flow study and optimization study. The first quarter and second quarter of phase three also begins the experimental set-up of secondary emission studies from niobium in superconducting mode. This …

Modeling, Fabrication, And Optimization Of Niobium Cavities, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

One of the key technologies for the deployment of acceleratordriven transmutation systems is the accelerator itself. Elliptical superconducting niobium cavities are used to increase the efficiency of the high-power accelerators needed to support the transmutation mission.

One of the major sources of energy loss from a superconducting accelerator cavity is a process known as multiple impacting (or “multipacting”) of electrons. This phenomenon limits the maximum amount of energy and power that the niobium cavity can store. As a result, the maximum power available for accelerating the desired charge, as well as the overall performance of the accelerator is reduced. Furthermore, …