粒子加速器超导射频腔制备过程中铌吸氢倾向的评价。

IF 1.5 4区 工程技术
R E Ricker, G R Myneni
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引用次数: 30

摘要

在铌超导射频(SRF)粒子加速器腔的制造过程中,采用化学或机械去除五氧化二铌(Nb2O5)钝化表面膜的方法。除去这层薄膜会暴露出下面的铌金属,并使其与加工环境发生反应。如果这些反应以足够的浓度和速率产生氢,那么氢就会被吸收并扩散到金属中。高的氢活度会导致过饱和和氢化物相成核。如果金属在加工步骤结束时再钝化,并且钝化膜阻止氢逸出,则吸收的氢或氢化物可能被保留并在随后的加工步骤或使用中改变金属的性能。本报告通过首先确定假定的事件、条件和反应,然后确定每个事件、条件和反应是否与公认的科学原则、文献和数据相一致,来检验这一假设的可行性。在科学文献中发现了其他系统中类似事件的先例,热力学分析发现,假设的反应不仅在能量上有利,而且产生了巨大的驱动力。测定反应达到平衡所需的氢活度或逸度,以表明氢的演化、吸收和氢化物成核的倾向。讨论了工艺条件和动力学对氢表面覆盖率接近理论值的影响。研究发现,SRF加工过程中氢气吸收的假设与已发表的科学文献和热力学原理是一致的。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Evaluation of the Propensity of Niobium to Absorb Hydrogen During Fabrication of Superconducting Radio Frequency Cavities for Particle Accelerators.

Evaluation of the Propensity of Niobium to Absorb Hydrogen During Fabrication of Superconducting Radio Frequency Cavities for Particle Accelerators.

Evaluation of the Propensity of Niobium to Absorb Hydrogen During Fabrication of Superconducting Radio Frequency Cavities for Particle Accelerators.

Evaluation of the Propensity of Niobium to Absorb Hydrogen During Fabrication of Superconducting Radio Frequency Cavities for Particle Accelerators.

During the fabrication of niobium superconducting radio frequency (SRF) particle accelerator cavities procedures are used that chemically or mechanically remove the passivating surface film of niobium pentoxide (Nb2O5). Removal of this film will expose the underlying niobium metal and allow it to react with the processing environment. If these reactions produce hydrogen at sufficient concentrations and rates, then hydrogen will be absorbed and diffuse into the metal. High hydrogen activities could result in supersaturation and the nucleation of hydride phases. If the metal repassivates at the conclusion of the processing step and the passive film blocks hydrogen egress, then the absorbed hydrogen or hydrides could be retained and alter the performance of the metal during subsequent processing steps or in-service. This report examines the feasibility of this hypothesis by first identifying the postulated events, conditions, and reactions and then determining if each is consistent with accepted scientific principles, literature, and data. Established precedent for similar events in other systems was found in the scientific literature and thermodynamic analysis found that the postulated reactions were not only energetically favorable, but produced large driving forces. The hydrogen activity or fugacity required for the reactions to be at equilibrium was determined to indicate the propensity for hydrogen evolution, absorption, and hydride nucleation. The influence of processing conditions and kinetics on the proximity of hydrogen surface coverage to these theoretical values is discussed. This examination found that the hypothesis of hydrogen absorption during SRF processing is consistent with published scientific literature and thermodynamic principles.

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来源期刊
自引率
33.30%
发文量
10
期刊介绍: The Journal of Research of the National Institute of Standards and Technology is the flagship publication of the National Institute of Standards and Technology. It has been published under various titles and forms since 1904, with its roots as Scientific Papers issued as the Bulletin of the Bureau of Standards. In 1928, the Scientific Papers were combined with Technologic Papers, which reported results of investigations of material and methods of testing. This new publication was titled the Bureau of Standards Journal of Research. The Journal of Research of NIST reports NIST research and development in metrology and related fields of physical science, engineering, applied mathematics, statistics, biotechnology, information technology.
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