DEVELOPMENT OF RECEIVER PROTECTOR FOR PULSED ESR

脉冲 ESR 接收器保护器的开发

• 批准号: 8363938
• 负责人: Jack H Freed
• 金额: $ 1.05万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8363938
• 关键词: Development; Electromagnetics; Frequencies; Funding; Grant; Home environment; National Center for Research Resources; Performance; Physiologic pulse; Principal Investigator; Recovery; Research; Research Infrastructure; Resources; Sampling Studies; Source; Specific qualifier value; Speed; Staging; Technology; Testing; Time; United States National Institutes of Health; Work; base; cold temperature; cost; design; ferrite; nanosecond; operation

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. The design work on the high-power stage of a receiver protector switch for 35 GHz is completed. We are integrating the ferrite switch with a fast, low-power, pin-diode switch that we recently acquired. We successfully tested a ferrite-based latching circulator intended for 35 GHz work. It is controlled by a home-built, fast, pulsed current driver. The switching speed is better than 20 ns, which is adequate for its use in FT-ESR. The repetition rate for this switch is 5 kHz, but we have not attempted to increase it further due to lack of a spare switch. The remaining work also includes minimizing electromagnetic interference from intense current pulses in its normal mode of operation as a part of the 35 GHz spectrometer. We routinely use 200 W limiters to handle 1-1.5 kW pulses of nanosecond duration for 8-18 GHz frequency range. For operating frequencies up to 18 GHz at higher peak power we recently procured passive receiver protectors rated to 1 kW for 1 ?s pulses. This would be adequate for nanosecond pulses of higher intensity. Their recovery time of 50 ns is adequate for low-temperature DQC work, but may be problematic for 2D-ELDOR for which dead-time should be under 30 ns. This would require a further effort to procure 20 ns ferrite switches and combine them with low-power diode limiters in order to achieve dead-time less than 25 ns. Ferrite switches for X and Ku bands with switching time under 20 ns are not available as standard products. What can be found is specified for larger switching energy than the 35 GHz switch, therefore we plan to obtain samples and study their switching performance.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的首席研究员可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 35 GHz 接收器保护开关高功率级的设计工作已经完成。我们正在将铁氧体开关与我们最近购买的快速、低功耗 pin 二极管开关集成在一起。我们成功测试了用于 35 GHz 工作的基于铁氧体的锁存环行器。它由自制的快速脉冲电流驱动器控制。开关速度优于 20 ns，足以用于 FT-ESR。该开关的重复率为 5 kHz，但由于缺乏备用开关，我们没有尝试进一步提高它。剩下的工作还包括最大限度地减少作为 35 GHz 光谱仪一部分的正常操作模式下强电流脉冲的电磁干扰。 我们通常使用 200 W 限制器来处理 8-18 GHz 频率范围内纳秒持续时间的 1-1.5 kW 脉冲。为了在更高峰值功率下工作频率高达 18 GHz，我们最近采购了额定功率为 1 kW、1 µs 脉冲的无源接收器保护器。 这对于更高强度的纳秒脉冲来说已经足够了。 其 50 ns 的恢复时间足以满足低温 DQC 工作，但对于死区时间应低于 30 ns 的 2D-ELDOR 可能会出现问题。 这需要进一步努力采购 20 ns 铁氧体开关，并将其与低功率二极管限制器结合起来，以实现小于 25 ns 的死区时间。 用于 X 和 Ku 频段且开关时间低于 20 ns 的铁氧体开关不作为标准产品提供。 可以发现的是比 35 GHz 开关具有更大的开关能量，因此我们计划获取样品并研究其开关性能。