Plasma synthesized doped boron nanopowder for magnesium diboride superconductors

描述（由申请人提供）：磁共振成像（MRI）扫描仪的可用性对公共卫生产生了重大影响，并且希望这些设备在美国和全世界范围内获得更大的可用性。限制可用性的主要因素是现有的超导磁体技术。目前，商用MRI磁体需要液氦（LHe）;然而，世界氦气供应正在减少，价格正在上涨。因此，MRI生产商正在推动开发基于不含LHe的二硼化镁（MgB 2）超导磁体的MRI系统。本项目的目标是开发通过等离子体合成工艺制成的掺杂硼纳米粉末，用于生产MgB 2。 该项目的第一阶段非常成功。等离子体合成工艺从10克实验室方法扩展到大于200克的工艺，该工艺可以生产初步评估MRI磁体所需的千米长导线。由碳掺杂的硼纳米粉末制成的电线具有大于105 A/cm 2的临界电流密度Jc，最大为8特斯拉。这些是迄今为止报道的世界上性能最高的MgB 2超导体线。这一重大改进超出了该计划的目标，并使基于MgB 2磁体的1.5和3特斯拉MRI在短期内（3-5年）可行。 第二阶段的具体目标是：1）生产多公斤数量的掺杂硼纳米粉末，并使用它来制造更长长度的MgB 2线; 2）通过增加等离子体合成系统的长期稳定性和容量来扩大硼纳米粉末的等离子体合成工艺;以及3）进一步开发和扩大气固合成工艺以制造MgB 2纳米粉末。特种材料公司将完成开发等离子体合成工艺所需的工作，以生产公斤级的硼纳米粉末，可用于制造商业MRI磁体所需的数千米导线。二硼化镁纳米粉末的开发将通过为二硼化镁线的原位和非原位制造提供原材料来降低风险。该项目将与线材制造商和MRI最终用户密切合作，以便基于MgB 2超导磁体的下一代MRI扫描仪可以在3-5年的时间内实现商业化。

DESCRIPTION (provided by applicant): The availability of magnetic resonance imaging (MRI) scanners is having a significant impact on public health, and greater availability of these units in the US and throughout the world is desired. A primary factor limiting availability is the existing superconductor magnet technology. Presently, commercial MRI magnets require liquid helium (LHe); however, the world's helium supply is decreasing and the price is increasing. As a result, MRI producers are pushing to develop MRI systems based on LHe-free magnesium diboride (MgB2) superconducting magnets. The goal of this project is to develop doped boron nanopowder made by a plasma synthesis process to be used for producing MgB2. Phase I of this project was highly successful. The plasma synthesis process was scaled from a 10 gram laboratory method to a greater than 200 gram process that can produce the kilometer length wires needed for preliminary evaluation of MRI magnets. Wires made from carbon-doped boron nanopowder had critical current densities, Jc, of greater than 105 A/cm2 out to 8 tesla. These are the world's highest performing MgB2 superconductor wires reported to date. This significant improvement exceeded the goals of the program and makes 1.5 and 3 Tesla MRIs based on MgB2 magnets viable in the near-term (3-5 years). The Phase II specific aims are 1) produce multiple kilogram quantities of doped boron nanopowder and use it to fabricate longer lengths of MgB2 wires; 2) scale up the plasma synthesis process for boron nanopowder by increasing the long-term stability and capacity of the plasma synthesis system; and 3) further develop and scale up a vapor-solid synthesis process to make MgB2 nano-sized powder. Specialty Materials, Inc. will complete the work necessary to develop the plasma synthesis process to produce kilogram-sized batches of boron nanopowder that can be used to fabricate multi-kilometer wires needed for commercial MRI magnets. MgB2 nanopowder development will provide risk mitigation by providing raw material for both in situ and ex situ fabrication of MgB2 wires. This project will be carried out in close collaboration with wire fabricators and MRI end users so that the next generation of MRI scanners based on MgB2 superconducting magnets can be commercialized in a 3-5 year timeframe.