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

Transmutation Sciences Materials (TRP)

This final report provides the activities and accomplishments of Modeling, Fabrication, and Optimization of Niobium Cavities – Final Phase. The fluid flow experiments for the etching of the superconducting cavity walls and baffle designs of phase II of the three phases has been completed leading to a MS thesis in December of 2003. Designing the experimental setup of secondary electron emission was well underway in early summer of 2003 when funding was made available for this portion of the study. By March 2004, many of the components of the experimental study reached UNLV with some assembly accomplished. The first secondary …

Secondary Electron Emission From Niobium At Cryogenic Temperatures, Anoop George, Robert A. Schill Jr., Richard Kant, Stan Goldfarb

Transmutation Sciences Materials (TRP)

• A Secondary Electron Emission test stand has been designed to study the initial conditions of secondary electrons emitted from niobium in cryogenic state.

• Secondary electron particle distributions have been studied for 0^o, 15^o, and 30^o beveled surfaces

• BCP and EP samples have been compared showing that the EP count is over twice as large as the BCP count

• Electron beam surface conditioning was examined. Conditioning appears to be sensitive to pulse duration and the number of impacts

• Good comparison have been shown between experiment and simulation

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

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 niobium superconducting cavities. The surface preparation can significantly affect the secondary electron emission yields. Such yields are used in design codes. Current codes use values obtained from niobium samples cleaned by a different means at temperatures other than the operating temperature. Secondary electron emission studies on LANL surface-cleaned niobium are conducted with preliminary data presented in this report at room temperature. Soon studies will be …

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

Transmutation Sciences Materials (TRP)

This quarterly report provides an update to the last phase of the Modeling, Fabrication, and Optimization of Niobium Cavities in the no-cost extension period. 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. In December of 2005, the software for the particle positioning detector was finally up …

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 accelerator driven 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. …