| Paper | Title | Page |
|---|---|---|
| TUPPO004 | ILC Testing Program at Cornell University | 176 |
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Cornell University’s superconducting cavity development program is one contributor to the global collaborative effort on critical SRF R&D for the ILC. We conduct R&D in support of the baseline cavity development as well as several alternate cavity development paths. For the baseline program we are preparing and testing ILC cavities. We have developed a new quench detection system and successfully applied it to ILC 9-cell and 1-cell cavities to find quench producing defects, which were characterized with subsequent optical examination. We have successfully repaired a 9-cell cavity using tumbling to raise the accelerating gradient from 15 to above 30 MV/m. We have identified quench producing defects in single-cell cavities using our large-scale thermometry system and subsequently extracted and inspected the defect region with an SEM. For the alternate R&D, we are developing reentrant cavity shapes with 70 mm and 60 mm apertures, and a simpler, potentially faster and less expensive electropolishing method called vertical electropolishing. We are also assisting in developing new cavity vendors by rapidly testing single-cell cavities they produced to qualify their fabrication methods. |
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| TUPPO033 | A Multiplexed RTD Temperature Map System for Multi-cell SRF Cavities | 276 |
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Temperature maps of the walls of operating SRF cavities are useful for research purposes and cavity production testing. Such mapping systems using RTD temperature sensors have been in use for single-cell cavities for many years. For multi-cell cavities, such as a 9-cell ILC cavity, having two wire leads per sensor becomes unmanageable for the desired 5,000 sensors in a vertical test cryostat. In recent years, multiplexed systems have been explored to reduce the wire count. A new technique to perform multiplexing of the sensors with no switching components inside the cryostat will be described. For N sensors placed on a cavity having wires routed using ribbon cables having M conductors, the number of wires to be routed out of the cryostat using this technique would typically be (4*N/M). Details of the switching circuitry, signal conditioning circuitry, the RTD sensor boards, and tests will be presented. |
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| THPPO034 | Cryogenic Heat Load of the Cornell ERL Main Linac Cryomodule | 638 |
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The proposed Cornell Energy Recovery Linac (ERL) will be a 5 GeV, 100 mA cw electron accelerator using SRF Cavities. The cryomodule design will be an extension of TTF technology. The cryogenic plant will be a significant portion of the ERL cost and an accurate estimate of the heat load is crucial to facility planning. A prototype main linac cryomodule is in the process of being designed. The configuration of the major module components is sufficiently known to allow calculation of the cryogenic heat loads to the helium cooling circuits of 1.8K, 5K, and an intermediate temperature in the vicinity of 80K. The results of ANSYS thermal modeling with nonlinear material properties will be presented along with analytic calculations to provide an itemization of the cryomodule heat loads. The optimal intermediate temperature will be shown to be just above 80K. The wall-plug power for the cryoplant will be estimated with COP’s provided by major helium-refrigeration vendors. |
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| THPPO035 | DC Conductivity of RF Absorbing Materials | 643 |
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Broadband RF absorbing materials are frequently utilized in particle accelerator environments. There are stringent requirements placed on some of these absorbers in regard to vacuum compatibility, radiation compatibility, and particulate generation, especially for absorbers in close proximity to the beamline such as in some higher order mode (HOM) load designs. For RF absorbers located directly on the beamline, their DC conductivity must also be large enough to drain away static charge that may be deposited onto them, since such static charge could deflect the particle beam. Ceramics and ferrite materials have often been used for such RF absorbers, and SRF applications tend to extended their use to cryogenic temperatures. Unfortunately, the DC conductivity of these materials often drops precipitously with temperature and they become excellent insulators at cryogenic temperatures. The results of recent DC conductivity tests of several of these RF absorbing materials will be presented. |
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| THPPO036 | Carbon Nanotube RF Absorbing Materials | 648 |
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There are limited choices available for broadband RF absorbing materials compatible with particle accelerator beamline environments, such as for use in higher order mode (HOM) loads. Ceramics and ferrites that have the vacuum, radiation, and particulate compatibility tend to have strong RF absorption over only a decade of frequency once above 1 GHz. Further, their properties often change considerably at cryogenic temperatures for SRF applications. Mixing carbon nanotubes (CNT’s) into a resin matrix has recently shown promise for providing a broader band of RF absorption. Development work has begun for mixing CNT’s into a ceramic matrix for compatibility with cryogenic accelerator beamlines. The status of the material development and tests will be presented. |
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| THPPO098 | Assembly Preparations for the International ERL Cryomodule at Daresbury Laboratory | 864 |
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The collaborative development of an optimised cavity/cryomodule solution for application on ERL facilities has now progressed to final assembly and testing of the cavity string components and their subsequent cryomodule integration. This paper outlines the testing and verification processes for the various cryomodule sub-components and details the methodology utilised for final cavity string integration. The paper also highlights the modifications required to integrate this new cryomodule into the existing ALICE cryo-plant facility at Daresbury Laboratory. |