FAST PFN-BASED DRIVER FOR X-BAND RF CIRCULATOR SWITCH

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。 在升级我们的X/Ku微波EPR光谱仪的背景下，正在考虑改进高衰减射频(R.F.)用于接收器保护的开关。如先前的一个子项目(SPID 0035)所述，该项目提出了一个拟议的循环器R.F.对于35 GHz的开关，我们开发了一种合适的方法来驱动铁氧体基环行器/隔离器波导R.F.在符合我们的快速脉冲光谱仪要求的时间刻度上进行开关。这是实现这种快速R.F.的关键要素。开关子系统一直是固态高压驱动器的规范和设计，能够通过开关S感应铁氧体元件提供非常快速的高值电流转换。 我们现在正在研究这种驱动器/开关技术在较低频率的接收器保护中的应用。对切换X/Ku环行器所需的能量进行了估算，并计算了必须达到的驱动电压和电流。为了充分保护接收器，我们的X/Ku光谱仪应用要求驱动器应提供约250微焦耳的开关能量(而Q波段器件为87微焦耳)，以便可靠地切换环行器铁氧体磁化状态。这意味着矩形脉冲半高宽约为25毫微秒，顺应性为1500伏，峰值约为56安培。我们之前在模拟和评估高速开关驱动器参数方面的经验表明，离散脉冲形成网络(PFN)可能是指定的具有挑战性的驱动器性能条件的首选解决方案。在先前的设计分析中，我们注意到PFN固有的充放电对称性也可以被利用来提供所需的互补重置脉冲。在可能的PFN拓扑结构中，结合我们可能采用的各种特性阻抗，根据我们以前的经验，我们将首先研究A型Guilleman形式的模拟，以确定最符合我们要求的源和负载阻抗。然后，我们将描述所需的环行器开关参数，并根据潜在供应商返回的设备规格改进到更严格的型号。根据这些信息，我们将对H.V.进行最终的设计改进。X/Ku接收器保护应用的开关参数。

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. In the context of upgrading our X/Ku microwave EPR spectrometers, consideration is being given to improved high-attenuation radiofrequency (r.f.) switching for receiver protection. As described in a prior subproject (SPID 0035), which presents a proposed circulator r.f. switch for 35GHz, we have developed a suitable means of driving a ferrite-based circulator/isolator waveguide r.f. switch on a time scale compatible with our fast pulse spectrometer requirements. A crucial element in realization of this fast r.f. switch subsystem has been the specification and design of a solid-state high-voltage driver capable of delivering an extraordinarily rapid, high value current transition through the switch?s inductive ferrite element. We are now studying the application of this driver/switch technology to receiver protection at lower frequencies. An estimate of the energy required to switch the X/Ku circulator has been made, and we have calculated the driver voltages and currents which must be attained. In order to adequately protect the receiver, our X/Ku spectrometer application requires that the driver should provide around 250 microjoules of switching energy (as opposed to 87 uJ for the Q-band device), in order to reliably switch the circulator ferrite magnitization state. This implies a rectangular pulse FWHM of approximately 25 nsec with a compliance of 1500 volts and a peak value of approximately 56 amperes. Our previous experience in simulation and evaluation of driver parameters for high-speed switching has demonstrated that a discrete pulse-forming network (PFN) would likely be the preferred solution to the challenging driver performance conditions specified. In the prior design analysis, we noted that the PFN's inherent charge/discharge symmetry could also be exploited to provide the needed complementary reset pulse. Of the possible PFN topologies in combination with the various characteristic impedances which we might employ, based on our previous experience we will first investigate simulations of the Type A Guilleman form to determine the source and load impedances which best meet our requirements. We will then characterize the desired circulator switch parameters and progress to a more exacting model based on device specifications returned by prospective vendors. On the basis of this information, we will then conduct a final design refinement of the h.v. switch parameters for the X/Ku receiver protection application.