Polarized Xenon Production: Multi-liter Accumulation

超极化气体（氙-129和氦-3）已被证明在结构和应用中具有实用性 功能性肺成像和量化肺部疾病。然而，与氦-3相比，氙便宜且储量丰富。它较低的扩散常数提供了优于氦的科学优势，抵消了其较低的旋磁比的缺点。在50%偏振下每小时产生六升（每十分钟一升）的偏振器的可用性，几乎是大多数现有偏振器的一百倍，将引发超偏振氙作为成像剂的广泛研究和应用。 UNH小组展示了一种新型的氙偏振器，它使气体混合物以相对较高的速度和沿着与激光束相反的方向流动。该偏振器显示出对于小批量超过60%的偏振和对于每小时超过4升的生产速率超过20%的偏振。该偏振器的品质因数（偏振乘以生产率）目前超过所有其他偏振器 技术的数量级。我们建议把产量再增加六到十倍。通常用于积累超极化氙的低温技术只能回收一升的几分之一所产生的极化的60%到80%，对于更大的积累来说更是少得多。我们提出的用于第一阶段STTR的新技术成功地证明了半升的100%回收率和一升的88%回收率。我们制造了一个原型冻结出细胞，实现了自动移动低温恒温器，并测试了我们现有的偏振器上的设备。此外，我们还解决了生产的关键材料问题 可扩展的实现。这种实现的简单扩展提供了几乎无限数量的超极化氙的积累和完全回收。在第二阶段，我们建议增加蓄电池的容量，改进控制硬件和软件，简化和自动化解冻程序。我们还全面解决了其余的限制，以扩大整个偏振器：偏振柱玻璃器皿设计，气流参数，和真空容量。增加激光输出和减小偏振器的物理尺寸是单独资助的STTR。这些综合开发将扩大我们的实验室原型，并将其转换为实用的商业化医院设备。

Hyperpolarized gases, both xenon-129 and helium-3, have demonstrated utility in structural and functional lung imaging and quantifying lung disease. In contrast to helium-3, however, xenon is cheap and abundant. Its lower diffusion constant offers scientific advantages over helium, offsetting the disadvantage of its lower gyromagnetic ratio. Availability of a polarizer producing six liters per hour (a liter every ten minutes) at 50% polarization, almost a factor of one-hundred over most existing polarizers, would trigger widespread investigations and applications of hyperpolarized xenon as an imaging agent. The UNH group demonstrated a new type of xenon polarizer that flows the gas mixture at relatively high velocity and low pressure along a direction opposite to the laser beam. This polarizer demonstrated polarization of over 60% for small quantities and 20% for a production rate of over four liters per hour. The figure-of-merit (polarization times production rate) of this polarizer presently exceeds all other polarizer technologies by an order of magnitude. We propose to increase the output by another factor of six to ten. The cryogenic technology routinely used to accumulate hyperpolarized xenon recovers only 60% to 80% of the produced polarization for a fraction of a liter and far less for larger accumulations. Our new technique proposed for Phase I STTR successfully demonstrated 100% recovery for one-half liter and 88% recovery for one liter. We fabricated a prototype freeze-out cell, implemented an automated moving cryostat, and tested the device on our existing polarizer. Furthermore, we solved the critical materials question to produce a scalable implementation. Simple extensions of this implementation offer accumulation and full recovery of virtually unlimited quantities of hyperpolarized xenon. In Phase II we propose to increase the capacity of the accumulator, improve the control hardware and software, and simplify and automate the thawing procedure. We also comprehensively address the remaining limitations to scaling up the entire polarizer: polarizer column glassware design, gas flow parameters, and vacuum capacity. Increasing laser output and reducing the physical size of the polarizer are separately funded STTRs. These combined developments will scale up our laboratory prototype and convert it to a practical commercially-available hospital-based device.