A "permanent" high-temperature superconducting magnet operated in thermal communication with a mass of solid nitrogen

This thesis explores a new design for a portable "permanent" superconducting magnet system. The design is an alternative to permanent low-temperature superconducting (LTS) magnet systems where the magnet is cooled by a bath of liquid helium. The new design involves a high-temperature superconducting (HTS) magnet that is cooled by a solid heat capacitor. An apparatus was constructed to demonstrate stable operation of a permanent magnet wound with Bi2223/Ag conductor while in thermal communication with a mass of solid nitrogen. The system includes a room-temperature bore and can func tion while it stands alone, detached from its cooling source, power supply, and vacuum pump. The magnet is operated in the 20-40 K temperature range. This apparatus is the first to demonstrate the operation of a superconducting magnet with a permis sible temperature variation exceeding a few degrees kelvin while a magnetic field is maintained for a useful duration. Models are developed to predict the experimental system's warming trend and magnetic field decay. The models are validated with a good agreement between simulations based on these models and experimental results. Potential performance advantages of a solid nitrogen cooled permanent HTS (SN2/HTS) magnet system over a liquid helium cooled LTS (LHe/LTS) system are explored for various applications. The SN2/HTS system design includes a second solid heat capacitor that cools a radiation shield. Recooling of the heat capacitors is performed with a detachable cryocooler. The SN2/HTS system offers both improved stability and improved portabilit over an LHe/LTS system design.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Haid, Benjamin J. (Benjamin John Jerome), 1974-

Advisor dc:contributor.advisor

• Yukikazu Iwasa.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/88893

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/88893