35 GHZ UPGRADE FOR PULSED ESR MICROSCOPE

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 我们将建立和发展一个工作在35 GHz的脉冲ESR显微系统（ESRM），这将改善我们目前的6- 17 GHz脉冲ESRM。升级后的系统将基于模块化频率设计的独立微波桥和脉冲成像探头，而控制计算机、梯度电流驱动器和磁体调节器系统将与现有的6- 17 GHz系统共享。我们期望更高频率的系统应该能够以约2x2 x5 um的改进分辨率采集各种生物样本的3D图像（参见图1）。呈现3 × 3 × 8 μ m）。 为了扩展我们目前脉冲ESRM的频率覆盖能力，我们将使用与现有系统中使用的收发器类似的收发器，并添加频率块转换器。这意味着在收发器和微波固态放大器之间增加9 GHz到35 GHz的频率块转换器，并且用适当的35 GHz放大器代替6- 18 GHz微波固态放大器。在这项开发结束时，我们将有两个特定频段的微波桥，工作在6- 18 GHz和35 GHz。目前，美国国家微波研究院正在研制微波块变换器和1- 10 W 35 GHz功率放大器。空白的研究小组在以色列海法的Technion研究所，并将提供给ACERT的组件成本的基础上，作为一个更广泛的ESR显微镜合作开发工作的一部分。 除了微波电桥的开发工作，我们还将在ACERT内部进一步开发所需的快速梯度线圈电流脉冲驱动器。我们的目标是实现产生短矩形梯度的能力，其中在短上升时间之后，梯度线圈中的电流对于脉冲序列保持恒定，然后迅速降低到零，从而限制耗散并最大化频率编码成像的允许重复率。

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 will construct and develop a pulsed ESR microscopy system (ESRM) designed for operation at 35GHz, which would improve upon our present 6-17GHz pulse ESRM. The upgraded system will be based on a separate microwave bridge of modular frequency design and pulse imaging probe, while the control computer, gradient current driver and magnet regulator systems will be shared with the existing 6-17GHz system. We expect the higher frequency system should enable the acquisition of 3D images of a variety of bio-samples with an improved resolution of ~2x2x5um (cf. present 3x3x8um) in a few minutes of acquisition. In order to extend the frequency coverage capability of our current pulsed ESRM, we will use a similar transceiver to that used in the existing system, with the addition of a frequency block converter. This implies the addition of a 9GHz to 35GHz frequency block converter between the transceiver and the microwave solid-state amplifier, and replacing the 6-18GHz microwave solid state amplifier by an appropriate 35GHz amplifier. At the end of this development, we will have two band-specific microwave bridges, operating at 6-18GHz and 35GHz. The microwave block converter and 1-10W 35GHz power amplifier are presently under development by the A. Blank research group at Technion Institute, Haifa, Israel, and will be made available to ACERT on a components-cost basis as part of a broader ESR microscopy collaborative development effort. In addition to the microwave bridge development work, we will further develop within ACERT the requisite fast gradient coil current pulse drivers. Our goal is to implement the capability to generate short rectangular gradients, where after a short rise time, the current in the gradient coil is maintained constant for the pulse sequence then rapidly reduced to zero, thereby limiting dissipation and maximizing the allowable repetition rate for frequency-encoded imaging.