DEVELOPMENT OF VERSATILE 8-18 GHZ FT ESR SPECTROMETER

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 我们在完成建造一台新的、通用的8-18 GHz FT-ESR光谱仪方面取得了重大进展。微波桥内部的微波脉冲形成单元、接收器和频率转换器已组装成最终配置，并在很大程度上与在Acert设计和建造的新计时系统相结合。我们最新的设计迭代计时系统使其能够以10皮秒的计时分辨率按顺序产生脉冲，并为适当的光谱仪组件提供所有必要的控制信号。目前，我们正在编写光谱仪控制固件和数据采集软件，并敲定小的硬件问题，以提高光谱仪级别的整体系统性能。目前的数据采集基于两个AP240双通道1 GSPS ADC/信号平均器PCI卡，它们捕获正交信号并以非常高的效率对其进行平均。新的光谱仪将使用新的4kW Ku波段和/或8 kW X波段行波管，其输出功率暂时限制在2 kW，直到建立新的高功率高速有源接收器保护阶段，以保护限幅二极管不受损害。光谱仪电桥与PULSE编程器和数据采集系统一起处于测试的最后阶段。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We made significant progress in finalizing the construction of a new, versatile 8-18 GHz FT-ESR spectrometer. The microwave pulse forming unit, receiver and frequency converters, internal to the microwave bridge, were assembled in their final configuration and to a large extent integrated with the new timing system designed and built at ACERT. Our latest design iteration of timing systems makes it possible to generate pulses in their sequences with 10 picosecond timing resolution and provide all necessary control signals for appropriate spectrometer components. Currently, we are in the process of writing spectrometer control firmware and data acquisition software and finalizing small hardware issues to improve overall system performance at the spectrometer level. The data acquisition is currently based on two AP240 dual-channel 1 Gsps ADC/signal averager PCI cards that capture quadrature signals and average them with very high efficiency. The new spectrometer will use new 4kW Ku-band and/or 8 kW X-band TWTAs with their output power temporarily limited to 2 kW until a new high-power high-speed active receiver protection stage is built to protect the limiting diode from damage. The spectrometer bridge is in the final stage of testing along with the pulse programmer and data collection system.