Neutron Scattering Instrumentation for Measurement of Melt Structure

[摘要] This Phase II research project was focused on constructing and testing a facility for the measurement of the structure of hot solid and liquid materials under extreme conditions using neutron diffraction. The work resulted in measurements at temperatures of 3300 K, the highest ever performed in a neutron beam. Work was performed jointly by Containerless Research, Inc. and Argonne National Laboratory with significant interactions with engineers and scientists at the under construction-SNS facility in Oak Ridge, TN. The work comprised four main activities: Design and construct an advanced instrument for structural studies of liquids and hot solids using neutron scattering. Develop and test a software package for instrument control, data acquisition and analysis. Test and demonstrate the instrument in experiments at the GLAD beamline at IPNS. Evaluate requirements for performing experiments at the SNS. Develop interest from the potential user base and identify potential support for Phase III. The objectives of the research were met. A second-generation instrument was developed and constructed. The instrument design drew on the results of a formal design review which was held at Argonne National Laboratory during the Phase I research [1]. The review included discussion with potential instrument users, SNS scientists and engineers and various scientists involved with materials, glass, ceramics, and geological sciences. The instrument combines aerodynamic levitation with pulsed neutron diffraction in a controlled atmosphere. An important innovation was the use of pure vanadium levitation nozzles that effectively eliminated contributions from the sample environment to the measured data. The instrument employed a 250 Watt CO2 laser that was configured for Class I laser operation. The use of Class I laser configuration meant that operators could work with the equipment with minimal restrictions and so concentrate on the research activities. Instrument control and data acquisition software was developed and implemented. As part of a larger initiative at IPNS, PC-based programs are being developed for acquisition and processing of neutron data. The PC-based beamline data handling system will enable compatibility with the levitator software. The instrument was bench tested at CRI and operated in three campaigns at the GLAD beamline at IPNS. Samples approximately 3.5 mm in diameter were levitated for periods up to 6 hours and at temperatures up to 3300 K. Structure factors were obtained for liquid oxide materials and hot solids. Details are given in this report and in published or submitted papers. During the course of the Phase I and Phase II projects, technical presentations were made at the Materials Research Society meeting in Boston, November, 2001, the American Conference on Neutron Scattering in Knoxville, TN, June, 2002, the Gordon Research Conference on High Temperature Chemistry (poster) in Waterville, ME, August 2002, the ACNS meeting in Baltimore, MD, June, 2004 and the Non-crystalline Materials-9 meeting in Corning NY, July, 2004. Two manuscripts were prepared, one is published, one is in review. The presentations have resulted in contact with the user community and we have received several requests to use the instrument. As a result, we are seeking support for collaborative research and plan to offer beamline instruments for commercial sale.

[发布日期] 2004-10-21 [发布机构] Containerless Research, Inc.

[关键词] 25 Energy Storage;Neutron Diffraction;Controlled Atmospheres;Neutrons;Aerodynamics