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
Closed-Loop Cryogenic Cooling for a 21 T FT-ICR Magnet System
A closed-loop cooling concept for 21 T Fourier transform ion cyclotron resonance (FT-ICR) superconducting magnets is presented. In the magnet system, low temperature superconducting coils are immersed in a subcooled 1.8 K bath, which is connected to the saturated helium reservoir through the weight load relief valve. Saturated liquid helium is refrigerated by a Joule-Thomson (JT) heat exchanger and flows through the JT valve, isenthalpically dropping its pressure to approximately 1.6 kPa, corresponding to a saturation temperature of 1.8 K. Helium gas exhausted from JT pump is liquefied by a two-stage cryocooler located after the vapor purify system. In the present paper, the amount of heat budget is determined and the structural design of cryostat is carried out by the relevant analyses. The position of a cryocooler in the magnet system is investigated, taking into account the requirement of magnetic field for normal performance. Helium liquefaction system, a key component of the closed-loop cooling system, is fabricated and tested in order to demonstrate the feasibility of our new cryogenic cooling for high field magnets.
Handbook on Materials for Superconducting Machinery
Abstract : The major objective of this Handbook is to present data that could be used in the development of new concepts in superconducting machinery. Information was collected on the mechanical, thermal, electrical, and magnetic properties of selected structural materials for designers and users of equipment that will be exposed to cryogenic temperatures. The data are presented as 'best-value' numbers from compilations of data in the temperature range 0 - 300K. Materials include Al and Al alloys, Cu alloys, Ni alloys, Nb alloys, Ti alloys, and steels.