射频超导腔用高纯铌材制备

Preparation of High Purity Niobium Ingots for RF Superconducting Cavities

摘要:

本文采用电子束炉高真空、不少于3次熔炼的工艺成功制备了大规格高纯铌铸锭。高纯铌铸锭的纯度达到99.99%,RRR值稳定的大于300,满足了射频超导腔用高纯铌材料的要求。高纯铌铸锭的RRR值主要受H、N、O、C等间隙元素的影响,随着熔炼次数的增加,气体元素可有效去除,RRR值也稳步增长。高纯铌化学元素的检测精度不足以完全与RRR值对应,应结合两参数来评价高纯铌铸锭的品质。

Abstract:

In this contribution, we present the preparation of high purity niobium ingot for RF superconducting cavities by more than three times electron beam melting under high vacuum. The purity of obtained high pure niobium ingots were more than 99.99%, and RRR value reached more than 300. High pure niobium ingots has reaches the standard specifications for RF superconducting cavities.The RRR value of high purity niobium ingot is mainly affected by the interstitial impurities such as H、N、O、C, while the standard of Ta content can be relaxed moderately. With increasing the number of electron beam melting, the interstitial impurities can be removed effectively, and RRR values grow steadily.The results show that, RRR value and impurity content should be combined to evaluate the quality of high purity niobium, while impurity content alone is insufficient.