Requirements and Conceptual Superconducting Magnet Design for a 21 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer
The National High Magnetic Field Laboratory (NHMFL) has identified as one of its next high-field persistent-magnet targets a 21 T superconducting magnet system to be used in a Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometer. The required fundamental parameters of a 21 T central field and 110 mm warm bore diameter are similar to those already successfully demonstrated in the NHMFL's Ultra-Wide Bore 900 MHz Nuclear Magnetic Resonance magnet system. However, there are several ancillary requirements of the FT-ICR spectrometer that require technical attention such as fringe field restrictions requiring shielding, length of uniformity zone, magnitude of inhomogeneity, horizontal orientation of the magnet axis and a limitation on the length of the cryostat. This paper describes the overall system requirements, features and status of the superconducting magnet conceptual design proposed for meeting these requirements
Quench detection and protection of the wide bore 900 MHz NMR magnet at the National High Magnetic Field Laboratory
A wide bore, high resolution NMR magnet with a proton resonance frequency of 900 MHz, field of 21.1 T, and stored energy of 40 MJ has been designed and fabricated at the NHMFL. The magnet has five Nb/sub 3/Sn and five NbTi coils, each of which contains stainless steel strip heaters. An active protection system with analog quench detection circuitry is employed to determine the onset of a quench and to subsequently open a superconducting protection switch and energize a portion of the strip heater network. A passive protection system with diode sets and shunting resistors exist for redundancy. Details of the protection system are presented and its performance during the magnet's bucket test is discussed.
Solitary Orbital Paget Disease: A Case Report
Purpose: To describe the clinical findings in a patient who had developed painless supraorbital prominence. Methods: Clinical and histopathological findings of the case are reviewed and presented. Results: The patient had an isolated histologically confirmed Paget disease of the orbit. Local excision of the lesion was performed. Conclusion: Paget disease can present not only as a diffuse process but also as a painless, solitary lesion of the orbit.