PRECISION FAST PULSED FIELD GRADIENT DRIVER FOR ESR MICROSCOPY

用于 ESR 显微镜的精密快速脉冲场梯度驱动器

• 批准号: 8363968
• 负责人: CURT R DUNNAM
• 金额: $ 0.05万
• 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/8363968
• 关键词: Address; Automobile Driving; Characteristics; Charge; Collection; Electric Capacitance; Feedback; Funding; Grant; Microscope; Microscopy; National Center for Research Resources; Output; Physiologic pulse; Principal Investigator; Regulation; Research; Research Infrastructure; Resolution; Resources; Scheme; Series; Source; Staging; System; Technology; Time; United States National Institutes of Health; Variant; Work; base; cost; design; electric impedance; magnetic field; nanosecond; novel; programs; research and development

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 our pulsed ESR microscopy research and development work, we plan to reduce coil dissipation at high collection rates by providing precise, fast constant-current pulses to the resonator gradient coil sets. In practice, this objective is difficult to achieve because the gradient coils represent a substantially inductive load, requiring that the pulse driver be capable of charging the coil's magnetic field to the requisite energy level in several tens of nanoseconds or so and also that the coil's inductance not resonate at high "Q" with parasitic system driver and cable capacitances. Also, during the gradient "on" time, the pulse amplitude variation must be held to less than 1%, in order to avoid degrading the microimage resolution. Finally, the driver must rapidly "dump" the stored coil energy following the end of the gradient pulse period. To address these issues, we have developed several possible implementation schemes for the fast pulsed gradient driver. Currently, we are evaluating a novel fast constant-current driver core as the basis for our present design options. The driver core network consists of a current-programmed "cascode" configuration, essentially a series-connected, open-loop MOSFET topology. This type of wideband driver stage is inherently current-regulating and therefore does not rely on a discrete closed-loop feedback network for its constant-current characteristic. As a result, its bandwidth and stability margin are relatively high and handily exceed the requirements for our application. We are presently evaluating this core network to determine if, in its open-loop form, it will adequately maintain the pulse amplitude regulation that our microscope application requires while driving a representative load impedance over the full programmed-output range. If the open-loop driver amplitude variation exceeds our specification, we will then explore the addition of a gated fast current feedback loop to further reduce the amplitude variation. Work on this project will continue through the 2005-6 year.

该副本是利用资源的众多研究子项目之一 由NIH/NCRR资助的中心赠款提供。对该子弹的主要支持 而且，副投影的主要研究员可能是其他来源提供的 包括其他NIH来源。 列出的总费用可能 代表subproject使用的中心基础架构的估计量， NCRR赠款不直接向子弹或副本人员提供的直接资金。 在我们的脉冲ESR显微镜研发工作中，我们计划通过为谐振器梯度线圈集提供精确的快速恒定脉冲来减少高收集速率的线圈耗散。实际上，这一目标很难实现，因为梯度线圈代表了基本的感应载荷，要求脉冲驱动器能够在几十纳米左右的几十纳秒左右将线圈的磁场充电到必不可少的能级，并且线圈的电感不在High“ Q”时与Parasitic System System驱动器和电缆驾驶员和电缆电容式相连。同样，在梯度“ on”时间时，脉冲振幅变化必须保持在小于1％，以避免降低微图像分辨率。最后，驾驶员必须在梯度脉冲时期结束后迅速“倾倒”存储的线圈能量。 为了解决这些问题，我们为快速脉冲梯度驱动器开发了几种可能的实施方案。当前，我们正在评估一种新颖的快速恒定驱动器核心，作为我们目前的设计选项的基础。驱动程序核心网络由当前编程的“ cascode”配置组成，本质上是串联的开放环MOSFET拓扑。这种类型的宽带驱动程序阶段本质上是电流调节的，因此不依赖离散的闭环反馈网络来实现其恒流特性。结果，它的带宽和稳定性边缘相对较高，并且可以轻松地超出我们应用的要求。我们目前正在评估此核心网络，以确定是否以开环形式确定我们的显微镜应用所需的脉冲振幅调节，同时在整个编程中的输出范围内驱动代表性负载阻抗。如果开环驱动程序振幅变化超过我们的规范，我们将探索添加封闭的快速电流反馈回路，以进一步减少幅度变化。 该项目的工作将持续到2005 - 6年。