Quench detection and protection of the wide bore 900 MHz NMR magnet at the National High Magnetic Field Laboratory

Author

Dixon, I.R. ; Markiewicz, W.D. ; Murphy, P. ; Painter, T.A. ; Powell, A.

Author_Institution

National High Magnetic Field Lab., Tallahassee, FL, USA

Volume

14

Issue

2

fYear

2004

fDate

6/1/2004 12:00:00 AM

Firstpage

1260

Lastpage

1263

Abstract

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 Nb₃Sn 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.

Keywords

niobium alloys; nuclear magnetic resonance; protection; quenching (thermal); superconducting coils; superconducting magnets; superconducting switches; tin alloys; titanium alloys; 21.1 T; 40 MJ; 900 MHz; National High Magnetic Field Laboratory; Nb₃Sn; NbTi; active protection system; analog quench detection circuitry; bucket test; diode sets; high resolution NMR magnet; magnet bucket test; passive protection system; proton resonance frequency; quench detection; quench protection; shunting resistors; stainless steel strip heaters; strip heater network; superconducting magnets; superconducting protection switch; wide bore NMR magnet; Boring; Laboratories; Magnetic fields; Magnetic resonance; Nuclear magnetic resonance; Protection; Strips; Superconducting coils; Superconducting magnets; Switches; Magnet; protection; quench; superconductivity;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/TASC.2004.830547

Filename

1325027