Preliminary results of the partial array LCT coil tests Page: 1 of 5
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'RELIMINARY RESULTS OF THE PARTIAL ARRAY ICT COIL TESTS*
J. N. Luton, F. D. Cogswell, L. Dresner, G. M. Friesinger,* W. H. Gray, Y. Iwasa,t K. KoizumiS M. S. Lubell,
J. W. Lue, M. F. Nishi,S S. D. Peckt S. S. Shen, R. Takahashi,5 R. E. Wintenberg, K. Yoshida,5 J. A. Zichy"
Oak Ridge National Laboratory
Oak Ridge, Tennessee 77830
The Large Coil Task (LCT) is a collaboration be-
tween the US, Euratom, Japan, and Switzerland for the
production and testing of 2.5 x 3.5-m bore, super-
conducting 6-T magnets. The definitive tests in the
E 5- design configuration, the six coils arrayed in a
u 4 compact torus, will begin in 1985. Partial-array
tests are being done in 1984. In January the initial
(J cooldown of two coils was aborted because of helium-
to-vacuum leaks that developed in certain seal welds
when the coil temperatures were 170 to 180 K. In July
W three adjacent coils (designated JA, GD, CH) were
* Z as cooled and in August two were energized to the limits
WA = of the test facility. An overview of the results are
p .rte= presented, including facility, cooldown (warmup has
-A = not yet begun), energization, dump, recovery from
e J intentional normal zones, strain, and displacement,
for operation up to 100% of design current but below
. C 0 full field and stress. These initial results are
j S t highly encouraging.
3 The Large Coil Test Facility (LCTF) in Oak Ridge
will contain six test coils, but for various reasons
three were available for early partial testing and
facility shakedown.1 Coil CH, provided by Switzerland,
was completely installed except for the electrical
bus.2 Coil JA, provided by Japan, is the only one
previously cooled and energized.3 Coil GD, manufactur-
ed by General Dynamics/Convair Division,4 was provided
by the US. The coils are 60* apart, with JA in the
middle, forming half of a six-coil compact toroidal
The first cooldown of the LCTF for two-coil tests
started Jan 10, 1984. Helium gas cooled with IN was
circulated through the test stand bucking post, upper
and lower torque rings, GD winding, GD structure, and
the JA coil. The cooldown criteria allowed an average
AT between the outlet and inlet helium to the coils of
50 K, but caution in the face of instrumentation
problems resulted in using only 19 K AT during the
first 3.5 days of cooldown. On Jan 14, at 230-250 K
range, IN was introduced to the cold walls. Tnis and
the smoother, higher average 6T (up to 41 K) of the
helium almost doubled the cooldown rate to 0.6 K/h.
On Jan 17, at 160-180 K, large helium leaks developed
inside the vacuum vessel and cooldown was halted. On
Jan 19 helium flows were re-established to warm up the
system. It went smoother than cooldown, though the
average rate was about the same as that of cooldown
*Research sponsored by the Office of Fusion Energy,
U.S. Department of Energy, under contract DE-AC05-
840R21400 with Martin Marietta Energy Systems, Inc.
tMassachusetts Institute of Technology, Cambridge, MA.
*Kernforschungszentrum Karlsruhe, Federal Republic of
Germany, currently on assignment at ORNL.
SJapan Atomic Energy Research Institute, Tokai, Japan,
currently on assignment at ORNL.
tGeneral Dynamics, Convair Division, San Diego, CA.
-. **Swiss Institute for Nuclear Research, Villigen,
Switzerland, currently on assignment at ORNL.
Manuscript received September 10, 1984
(0.6 K/h). On Jan 25 the tank was let up to air; the
next day the lid was removed with temperatures ranging
from 255 to 275 K.
The leaks proved to be in the GD coil, at ports
earlier used for urethane filler injection, and it was
necessary to remove the coil from the tank to gain
access for repair. During that time its inside-the-
tank cabling an/i associated connectors were reworked
for higher voltage-withstand capability. Evacuation
of the tank started on June 14 and cooldown (Fig. 1)
on July 3. Above %100 K, the cooldown rate was limited
by the available GHe mass flow and the particular
cooldown criterion limiting the GHe AT to 50 K. Below
100 K, where LN heat exchanger cooling lost effective-
ness, AT was less than 20 K, limited by the refrigera-
tor turbine. In the final stages of cooldown (Fig. 2),
the resistances of the coils dropped abruptly at the
expected 9.2 K critical temperature.
High-voltage tests on the upgraded GD system were
repeated when the coil and lead dewar contained Lhe,
the tank pressure was %105 torr, and all electrical
systems were attached. The conductor-to-ground with-
stand capability, 600 V, was disappointing, so the dump
resistor taps were changed to give a dump voltage
(from 10.2 kA) of 530 V rather than 745 V. Prior to
the magnet charging tests, a comprehensive series of
low-current (500-A) tests were performed to insure the
proper function of power supply, dump resistor, breaker
circuit, Programmable Logic Controller (PLC) interlock
c ,ra. . a , ,
r+- tr r[D" i3 s . ~ o "S' "E 3'
Lm '*':: - "".a
- n n ?33 0. " sr"o" c.' ".a
11 s " - -32. oa
*c"'" . r
F I I p
"1BCtO, uu w:c.-t 7
3 a30 a .-COQ. n uw:
r o.f I anrc I
,: 01 U 14 22 2 2.k
' s e e -- - -a 3. . is as
Fig. 1. History of the cooldown starting July 3, 1984
for (a) the facility structure and (b) the three coils.
DISTNIBUTIOg OF 103 NOWET IS UNti ai R )
I - r) -A
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Luton, J.N.; Cogswell, F.D.; Dresner, L.; Friesinger, G.M.; Gray, W.H.; Iwasa, Y. et al. Preliminary results of the partial array LCT coil tests, article, September 10, 1984; United States. (digital.library.unt.edu/ark:/67531/metadc1205208/m1/1/: accessed January 16, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.