Superconducting OHMIC-heating coils for the Argonne TEPR design study Page: 3 of 5
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?lbTi superconductor is limited to around 80 kG. A
5stter charging scheme for a superconducting OH coil
is shown in Fig. lb. This charging scheme requires
only half as many ampere-turns and permits the maxi-
mum central field to be reduced by 50% relative to the
charging scheme shown in Fig. la, for the same volt-
sec requirements. If the required flux change is
2 LpI, then the maximum central field and core area
pnust satisfy2 OHC 1
a rv x B Z (2 Lplp).
OH ,WITH OOTST550
CURRENT / Cesstmr
T.1r
TS TIME
rlsouT
a. Charging Scheme for Copper Coil
ON
CURRENr WITHOUT
+"iooo-. - - ___ T UR
r1TN "pp73TR'F
CURRENT
0- I TIME
REC. + o SEC. _(4)
b. Charging Scheme for Superconducting Coil
Fig. 1. Charging Schemes for Normal and
Superconducting OH Coils
To summarize the comparison between the normal-
coil primary and the superconducting primary, the
superconducting system requires half the ampere-
turns, has a much smaller power loss, and needs a
simpler power supply. For the same size core, the
normal c'ils require twice the field in the core. The
superconducting OH coil has been chosen for the design;
however, if for some unforeseen reason suitable
superconducting coils could not be made, normal coils
would also work.
IV The OH Coils of the Argonne Design
The OH coils are located outside the TF (Toroidal
Field) coil system. Ideally there should be a system
of OH coils completely enclosing the plasma and TF
coils, so that there would be a large magnetic flux
linking the plasma but no magnetic field within the
enclosure itself due to the OH coils. This lack of field
would both improve the plasma stability and prevent
energy losses in the toroidal field coils due to pulsed
fields. A possible configuration is depicted in Fig. 2.
Such a system, however, conflicts with the need for
easy access to the plasma region for beam injectors,
plumbing, vacuum pumps, primary coolant, remote
maintenance equipment, etc. Consequently, the OH-
coil configuration was designed as shown in Fig. 3.
It consists of a 13 m long solenoid plus ten other coils,
producing fields of only about ten gauss in the plasma
region while supplying the needed 73 volt-sec. The
detailed winding dimensions and magnet characteristics
are listed in Table 1.i
-I.
. * * *% . ... I. -.
tel... r.-r 1 ,y.1
Fig. 3. Field Resulting From OH Coils Alone
In the table, RI, R2. Z1, and Z2 represent the inner
and outer radii and lower and upper axial coordinates,
respectively. The radius rv of the flux-linkage core
is 1. 9 meters, so the required central field is 32 kG.
The total conductor length is 627. 8 x 106 amperg-
meters, and the total ampere-turns is 45. 5 x 10 . All
field calculations were computed with full coil cross
section and without filamentary approximations. The
magnitude and direction of the OH-coil field are
indicated in Fig. 3.og 2 al
"i
Fig. 2. Ideal ON Coil Configuration
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Turner, L. R.; Wang, S. T. & Purcell, J. R. Superconducting OHMIC-heating coils for the Argonne TEPR design study, article, January 1, 1975; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc866842/m1/3/: accessed March 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.