The U.S. NHMFL 60 T long pulse magnet failure Page: 2 of 5
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The U. S. NHMFL
60 T Long Pulse Magnet Failure
James R. Sims, Josef B. Schillig, Gregory S. Boebinger, Hideyoshi Coe, Alan W. Paris, Michael J.
Gordon, Michael D. Pacheco, Terri G. Abeln, Richard G. Hoagland, Martin C. Mataya, Ke Han, and
Aferdita Ishmaku'Abstract-The 60 T long pulse magnet operated by the U. S.
National High Magnetic Field Laboratory at Los Alamos
National Laboratory, Los Alamos, New Mexico failed
catastrophically on July 28, 2000. The failure was investigated
and the cause was determined to be unusually low toughness in
the nitrogen strengthened manganese stainless steel (Nitronic-
40TM) reinforcing material. The source of the reduced toughness
condition was a sigma phase conversion in the microstructure.
The magnet failure, failure investigation and results of the
investigation are described. Plans for the construction of the
successor magnet, the 60 tesla long pulse Mark II, are described.
Index Terms-Failure investigation, high field, Nitronic-40TM,
pulsed magnet, sigma phase.
1. INTRODUCTION
T HE 60 tesla long pulse (60 T LP) magnet operated by the
National High Magnetic Field Laboratory at Los Alamos
National Laboratory was in use for 15 months before failing
on July 28, 2000 [1],[2]. The failure occurred without
warning and significantly before the expected design life of
10,000 full field pulses. The magnet operated well and as
expected. A total of 914 pulses were made; 401 of these were
full field (57.5 T or higher) pulses. It produced unique high
field long pulse and controlled pulse profiles for researchers.
Data were collected for over 25 refereed papers. Among these
articles are six Physical Review B papers, three Physical
Review B Rapid Communications, two Physical Review
Letters, and an article in Nature. The Nature article presents
specific heat measurements showing the collapse of the
Manuscript received September 24, 2001. This work was supported in
part by the U.S. National Science Foundation through the National High
Magnetic Field Laboratory
James R. Sims, Josef B. Schillig, Gregory S. Boebinger, Hideyoshi Coe,
Alan W. Paris, Michael J. Gordon, and Michael D. Pacheco are with the Los
Alamos National Laboratory and the National High Magnetic Field
Laboratory, Los Alamos, NM 87545 USA (telephone: 505-665-1975, 505-
665-1667, 505-665-8092, 505-667-6674, 505-665-4891, 505-665-4891,
505-665-0434 e-mail: jsimsglanl.gov jschilligglanl.gov gsbglanl.gov
coeglanl.gov aparisglanl.gov, mgordonglanl.gov mpachecoglanl.gov ).
Terri G. Abeln., Richard G. Hoagland, and Martin C. Mataya are with the
Los Alamos National Laboratory, Los Alamos, NM 87545 USA. (telephone:
505-667-9605, 505-667-1622, 505-667-1155 e-mail: tabelnglanl.gov
hoaglandglanl.gov matayaglanl.gov ).
Ke Han and Aferdita Ishmaku are with the National High Magnetic Field
Laboratory, Tallahassee, FL 32310 USA, (telephone: 850-644-6746, 850-
644-2036 e-mail: han@magnet.fsu.edu ishmakugmagnet.fsu.edu).correlation energy gap above 40T in a Kondo insulator.
These are the first specific heat measurements above 35T and
the first ever taken in a pulsed magnet. Fig. 1 is a photograph
of the 60 T LP magnet system installed in its pit.
II. THE MAGNET FAILURE
The magnet failed at peak field on the first pulse of the day.
The power supplies and all control systems operated correctly
and as expected during this pulse. There were no observed
anomalies prior to the failure, and routine magnet inductance
and resistance measurements made prior to the pulse
produced normal values. Records of the power supply
currents and voltages indicate that the failure likely began in
the middle coil group (coils six and seven). However there
are also indications that the failure could have initiated in the
innermost group of coils (coils one through five). The failure
was rapid and completely destroyed the magnet, its dewar and
adjacent busbar and other magnet utilities. The failure
engulfed the entire magnet within about 5 ms. Connections to
the power supply were lost within an estimated 13 ms. It is
also estimated that some of the individual coils of the magnet
failed within 100 to 200 microseconds of being overloaded.
Based on magnet failure simulations, the power levels
experienced during magnet failure were estimated to be
between 8 and 80 GW. The rapid progression of the failure
precluded any mitigation by the power supply or the
protection system.
There was minor damage to the magnet pit which housed
the magnet and no significant damage to the nearby power
supply. No persons were injured as the facility was always
evacuated prior to a magnet pulse. Magnet design coupled
with the nature of the failure produced a two lobed debris
pattern principally directed in an outward radial direction
from the magnet horizontal mid-plane. There were also
indications that the failure produced a brief but significant
fireball which scorched magnet pit walls and an adjacent
interior facility wall. The magnet pit retained 98.5% of the
magnet debris by weight. Photographs of the magnet system
taken shortly after the failure are available upon request for
the purposes of analyzing safety procedures required for safe
operation of such a large pulsed magnet system.
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Schillig, Josef B.; Boebinger, Gregory S.; Coe, Hideyoshi; Paris, Alan W.; Gordon, Michael J.; Pacheco, Michael D. et al. The U.S. NHMFL 60 T long pulse magnet failure, article, January 1, 2001; United States. (https://digital.library.unt.edu/ark:/67531/metadc929776/m1/2/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.