MODULATED GRADIENT COIL DRIVER FOR CW ESR IMAGING

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 用于c.w.的完整调制梯度线圈驱动器（MGCD）的构建- ESR显微成像继续进行，正如我们最近（2003年）的进展报告所述。已完成了MGCD输出部分电子组件原型的制造、测试和实现，并将该子系统集成到我们的3-D c.w.中。ESR成像显微镜/光谱仪，迄今已达到10 <$m x 10 <$m x 30 <$m的分辨率（在最近接受的Rev. Sci. Inst. article）. MGCD持续发展的主要动机是对实时波形生成硬件的显而易见的需求，该硬件能够提供成像共振器梯度磁场的快速更新的复杂调制。我们的MGCD基于硬件的波形发生器，在其最终版本，将取代现有的软件生成的波形子系统。通过结合预定义的线圈激励功能以及预加载和快速更新各个线圈驱动水平的能力，离散体素采集之间的死区时间将相对于我们目前的解释性计算机驱动激励系统减少一个数量级或更多。计算机开销也将减少一个数量级或更好，因为CPU将不再需要实时计算和更新梯度线圈电流。MGCD系统模块的一个重要次要特性是，它包括B 0的共模偏移，以增强光谱仪AFC作用。预计未来可能的随机CW成像技术的调查，我们还设计到MGCD足够的处理和驱动带宽，允许梯度场调制的快速伪随机序列。目前，在第二阶段，我们已经完成了主要的信号处理电路板的建设，这将是调试，并很快安装在c.w. ESR显微镜与配套的绕线版本的函数发生器/控制器电子子系统，因为我们继续与三维c.w.显微成像项目。

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. Construction of the complete Modulated Gradient Coil Driver (MGCD) for c.w.-ESR microimaging continues, as described in our most recent (2003) progress report. Fabrication, test and implementation of a prototype MGCD output section electronic assembly has been completed, and this subsystem has been integrated into our 3-D c.w. ESR imaging microscope/spectrometer which has achieved resolution to date of 10¿m x 10¿m x 30¿m (described in a recently-accepted Rev. Sci. Inst. article). The primary incentive for continuing development of the MGCD has been the readily evident need for real-time waveform generation hardware which is capable of providing rapidly-updated, complex modulation of imaging resonator gradient magnetic fields. Our MGCD hardware-based waveform generator, in its final version, will take the place of the existing software-generated waveform subsystem. By incorporating pre-defined coil excitation functions and a capability of preloading and rapidly updating individual coil drive levels, the deadtime between discrete voxel acquisitions will be reduced by an order of magnitude or more relative to our present interpretive computer-driven excitation system. Computer overhead will also be reduced by an order of magnitude or better, since the CPU will no longer be required to calculate and update the gradient coil currents in real-time. An important secondary feature of the MGCD system module is that it includes common-mode offsetting of B0 as necessary to augment spectrometer AFC action. Anticipating possible future investigation of stochastic CW imaging techniques, we have also designed into the MGCD sufficient processing and driver bandwidth to permit gradient field modulation by fast pseudo-random sequences. Presently, in Phase II, we have completed construction of the main signal processing circuit board, which will be debugged and soon installed in the c.w.-ESR microscope with a companion wire-wrapped version of the function generator/controller electronics subsystems as we proceed with the 3-D c.w. microimaging project.