Plasma synthesized doped boron nanopowder for magnesium diboride superconductors

描述(申请人提供)：磁共振成像(MRI)扫描仪的可用性正在对公众健康产生重大影响，希望在美国和世界各地更多地使用这些设备。限制可获得性的主要因素是现有的超导磁体技术。目前，商用磁共振磁体需要液氦(LHe)，然而，世界氦的供应量正在减少，价格也在上涨。因此，磁共振成像生产商正在推动开发基于不含LHe的二硼化镁(MgB2)超导磁体的磁共振成像系统。本项目的目标是开发等离子体合成工艺制备的掺杂纳米硼粉末，用于生产硼化镁。该项目的第一阶段非常成功。等离子体合成过程从10克的实验室方法扩展到200克以上的过程，可以生产初步评估MRI磁体所需的公里长的导线。由碳掺杂的纳米硼粉末制成的导线的临界电流密度Jc在8特斯拉范围内大于105A/cm2。据报道，这些是迄今为止世界上性能最好的硼化镁超导线材。这一重大改进超出了该计划的目标，并使1.5特斯拉和3特斯拉磁共振成像在短期内(3-5年)变得可行。第二阶段的具体目标是1)生产几千克掺杂量的纳米硼粉末，并用它来制造更长长度的硼化镁线材；2)通过提高等离子体合成系统的长期稳定性和能力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，以制备纳米级的镁粉。特种材料公司将完成开发等离子合成工艺所需的工作，以生产公斤大小的纳米硼粉末，这些粉末可用于制造商业核磁共振磁体所需的数千米导线。通过为原位和非原位制造镁B2线材提供原材料，纳米级镁粉的开发将提供风险缓解。该项目将与线材制造商和核磁共振终端用户密切合作，以便在3-5年内将基于镁B2超导磁体的下一代核磁共振扫描仪商业化。 与公众健康相关：该项目将开发纳米硼粉末，这是基于二硼化镁(MgB2)磁体的下一代磁共振成像(MRI)扫描仪最关键的原材料。这些新的核磁共振扫描仪将更便宜，更高效，更便携，能够更早和更快地诊断医疗问题，并将在全国和世界范围内更广泛地使用。

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. PUBLIC HEALTH RELEVANCE: This project will develop boron nanopowder, the most critical raw material for the next generation of magnetic resonance imaging (MRI) scanners based on magnesium diboride (MgB2) magnets. These new MRI scanners will be much less costly, more efficient, more portable, capable of diagnosing medical problems earlier and faster, and will be much more widely available throughout the country and world.