HYBRID PULSED FIELD GRADIENT COIL DRIVER

混合脉冲场梯度线圈驱动器

• 批准号: 8363980
• 负责人: CURT R DUNNAM
• 金额: $ 0.53万
• 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/8363980
• 关键词: Development; Development Plans; Diffusion; Dimensions; Frequencies; Funding; Grant; Heating; Hybrids; Image; In Situ; Magnetism; Measures; Microscopy; National Center for Research Resources; Physiologic pulse; Principal Investigator; Relaxation; Research; Research Infrastructure; Resources; Scheme; Slice; Source; System; Technology; Testing; Time; United States National Institutes of Health; Viscosity; base; cost; design; design and construction; imaging probe; instrumentation; microwave electromagnetic radiation; nitroxyl; prototype

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. To further enhance our instrumentation capability in pulsed ESR microscopy, where unlike c.w., the experimenter can directly measure many key parameters such as self diffusion, relaxation times of the magnetic probe, viscosity, accurate O2 concentration, etc., we have designed a programmable pulsed field gradient coil driver of advanced capability. Based on a hybrid topology consisting of our existing gated-haversine coil excitation scheme and a fast-switched constant-current source, the new gradient coil driver design can be operated in either a prgrammable "rectangular" mode to accommodate our need for time-invariant gradients during the pulse sequence, or the previous fast "haversine" gradient excitation mode. The main advantage of a fast pulsed rectangular gradient is that it can be turned on, for example, only during each imaging pulse sequence, which enables the operator to avoid the problem of a heat producing constant gradient in one of the dimensions for frequency-encoded imaging applications. Ultimately, with further development, we expect to be able to produce short rectangular gradient pulses of ca 100ns at 0.5% stability. Such gradients can be selectively turned on during a specific microwave pulse which would permit, e.g., the possibility for slice selection imaging capability. Furthermore, when operating in the mode of our present haversine current driver, the new hybrid design would be capable of stronger and shorter pulsed field gradients which are necessary to support ESRM studies of nitroxide radicals with T2's in the 100  400ns range. After the planned developments and improvements in the gradient drivers, it is anticipated that the imaging probes will be able to generate haversine pulsed field gradients with durations of ~80 ns. A two-channel prototype "hybrid" pulsed field gradient coil driver has been designed and constructed and is presently under test. During the coming year, this unit will replace the existing haversine-only coil driver system, and continuing developmental upgrades will be incorporated and evaluated in situ.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 为了进一步增强我们在脉冲 ESR 显微镜方面的仪器能力，与连续波不同，实验者可以直接测量许多关键参数，如自扩散、磁探针的弛豫时间、粘度、准确的 O2 浓度等，我们设计了一种可编程脉冲 ESR 显微镜。具有先进能力的场梯度线圈驱动器。基于由我们现有的门控正矢线圈激励方案和快速开关恒流源组成的混合拓扑，新的梯度线圈驱动器设计可以在可编程“矩形”模式下运行，以满足我们对时不变的需求脉冲序列期间的梯度，或先前的快速“半正矢”梯度激励模式。快速脉冲矩形梯度的主要优点是，例如，它可以仅在每个成像脉冲序列期间打开，这使得操作员能够避免在频率编码的维度之一中产生恒定梯度的热量问题成像应用。 最终，随着进一步的发展，我们预计能够以 0.5% 的稳定性产生约 100ns 的短矩形梯度脉冲。这种梯度可以在特定的微波脉冲期间选择性地打开，这将允许例如切片选择成像能力的可能性。此外，当在我们目前的半正矢电流驱动器模式下运行时，新的混合设计将能够提供更强、更短的脉冲场梯度，这对于支持 T2 在 100 400 ns 范围内的硝基氧自由基的 ESRM 研究是必需的。在梯度驱动器的计划开发和改进之后，预计成像探头将能够生成持续时间约为 80 ns 的半正弦脉冲场梯度。 已经设计和建造了双通道原型“混合”脉冲场梯度线圈驱动器，目前正在测试中。在接下来的一年里，该装置将取代现有的半正弦线圈驱动器系统，并将在现场纳入和评估持续的开发升级。