DESIGN & CONSTRUCTION OF CRYOGENIC FTMS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 作为与心血管蛋白质组学中心合作的项目，低温FTMS的设计和开发是目前的一个主要项目。该仪器目前正在建造中，等待应于2005年夏天交付的磁铁。 傅里叶变换质谱仪的基本性能特性(分辨率、灵敏度、质量精度等)受到三个基本仪器限制：压力、磁场强度和前置放大器噪声。对低压的需要意味着需要大口径以获得对泵的大电导，但是对具有高均匀性的高场的需要意味着需要小口径以简化磁体设计。设计一种在超导磁体冷孔中运行的FTMS消除了这一矛盾，因为冷孔本身变成了一个低温泵。由于冷孔充当低温泵，离子转移真空室可以比正常情况下更窄，允许使用比FTMS中通常使用的更窄的孔磁铁，同时在50K下仍能达到所需的60W。因为更窄的3？该磁体已设计为15特斯拉磁体，将在14特斯拉时达到验收规格。内孔设计有两个铜安装支架，它们将用作FTMS内部真空室的热锚。然而，由于所涉及的表面积很大，主要的热传递将是直接的径向辐射热传递，这将使沿真空室墙壁流动的大部分热在50K屏蔽体到达4K区域之前被传递到50K屏蔽体。热分析表明，建立一个真空室是可能的，它可以将不到0.5W的热量从源传输到电池。该仪器目前正在建造中，磁铁的安装工作尚未完成。该磁体已达到磁场(14T)和均匀规格(在40 mm长、40 mm直径的圆柱体上的10ppm)，目前正在最终的杜瓦中进行真空测试。 磁体安装在BUSM上，MET场强为14T，并组装了离子源。FTMS插页已汇编完毕，初步数据已准备就绪并提交供出版。目前，该系统正在升级，配备了低噪声前置放大器，ICR单元的对准、对中和电气连接正在改进。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The design and development of the Cryogenic FTMS, as a collaborative project with the Cardiovascular Proteomics Center, is a major project at the moment. The instrument is currently under construction and awaiting the magnet which should be delivered in the summer of 2005. Fourier Transform Mass Spectrometry is limited in its base performance characteristics (resolution, sensitivity, mass accuracy, et cetera) by three fundamental instrumental limitations, pressure, magnetic-field strength, and preamplifier noise. The need for low pressure implies need for a large bore for large conductance to the pumps, but the need for high field with high homogeneity implies the need for low bore diameter to simplify magnet design. Designing an FTMS for operation in the cold bore of a superconducting magnet eliminates this contradiction as the bore itself becomes a cryopump. Because the cold bore acts as a cryopump, the ion transfer vacuum chamber can be made substantially narrower than normal, allowing use of narrower bore magnets than are normally used in FTMS while still achieving the needed 60W at 50K. Due to the narrower 3? bore, the magnet has been designed as a 15 Tesla magnet which will achieve acceptance specifications at 14 Tesla. The bore is designed with two copper mounting brackets which will function as thermal anchors for the inner FTMS vacuum chamber. However, due to the large surface areas involved, the primary heat transfer will be due to direct radial radiative heat transfer, which will allow most of the heat flowing down the vacuum chamber walls to be transferred to the 50K shield before it reaches the 4K region. Thermal analysis shows that it is possible to build a vacuum chamber which can transmit less than 0.5W of heat from the source to the cell. The instrument is now under construction, and installation of the magnet id pending. The magnet has met field (14T) and homogeneity specifications (10 ppm over a 40 mm long by 40 mm diameter cylinder) and is currently being vacuum tested in the final dewar. The magnet was installed at BUSM and met field at 14T, and the ion source is assembled. The FTMS insert was assembled, and initial data is available and submitted for publication. Currently, the system is being upgraded with the low noise preamplifier and alignment, centering, and electrical connections at the ICR cell are being improved.