FAST PFN BASED DRIVER FOR FERROMAGNETIC R F SWITCH

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。 该中心的高功率35 GHz FT-ESR脉冲光谱仪的成功实现要求包括快速、高衰减射频(R.F.)用于接收器保护的开关。如上所述(子项目：35 GHz脉冲ESR接收保护器的研制)，我们先前已经开发了铁氧体基环行器/隔离器波导的原型。在35 GHz频率范围内用于接收器保护的开关。这是实现这种快速R.F.的关键要素。开关子系统是我们设计和组装的固态高压驱动器，能够通过S电感铁氧体元件提供非常快速的高值电流转换。为了充分保护接收器，这种超快开关应用要求驱动器必须提供符合1200伏和峰值约25安培的半高宽20毫微秒的矩形脉冲。我们之前在模拟和评估用于高速开关的驱动器参数方面的经验已被用于确定脉冲形成网络(PFN)将是指定的具有挑战性的驱动器性能条件的首选解决方案。在初步设计分析中，我们注意到PFN固有的充放电对称性也可以用来提供所需的互补重置脉冲。在可能的PFN拓扑结构中，结合我们为评估和优化而模拟的各种特性阻抗，我们确定了36欧姆的A类Guilleman形式最符合我们的要求。当连接到速度适当的高压电源时。开关，我们观察到我们的原型3级PFN驱动器导致环行器/隔离器切换入射R.F.能量在非常短的10？20 ns的间隔内。我们目前正在根据光谱仪电桥R.F.来描述35 GHz接收器保护要求。参数，并在此信息的基础上；然后我们将对H.V.进行最终设计改进。切换此应用程序的参数。

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. Successful realization of the Center's high-power 35 GHz FT-ESR pulse spectrometer mandates inclusion of fast, high-attenuation radiofrequency (r.f.) switching for receiver protection. As described elsewhere (Subproject: Development of Receiver Protector for 35 GHz Pulsed ESR), we have previously developed a prototype ferrite-based circulator/isolator waveguide r.f. switch for receiver protection in the 35 GHz frequency regime. A crucial element in realization of this fast r.f. switch subsystem is our design and assembly of a solid-state high-voltage driver capable of delivering an extraordinarily rapid, high value current transition through the switch¿s inductive ferrite element. In order to adequately protect the receiver, this ultrafast-switching application requires that the driver must provide a rectangular pulse of FWHM 20 nsec with a compliance of 1200 volts and a peak value of approximately 25 amperes. Our previous experience in simulation and evaluation of driver parameters for high-speed switching has been utilized in determining that a pulse-forming network (PFN) would be the preferred solution to the challenging driver performance conditions specified. In the preliminary 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 simulated for evaluation and optimization, we have determined that the Type A Guilleman form at 36 ohms best meets our requirements. When coupled to a suitably fast h.v. switch, we observe that our prototype 3-stage PFN driver causes the circulator/isolator to switch incident r.f. energy in a notably short interval of 10 ¿ 20 ns. We are presently characterizing the 35GHz receiver protection requirements in terms of the spectrometer bridge r.f. parameters and, on the basis of this information; we will then conduct a final design refinement of the h.v. switch parameters for this application.