US tokamak research Page: 7 of 13
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20 —
i_
L
i
F
I0(-
! I|3
j y y y
= SC KG
: 0.4 MS '
‘ eo
T10
2.0
1.5
Te.Ti
keV
o[-_J_:_:___;_, : 1(3
1.0 2.0 3.0 4.0 5.0
ne (lO1'3 cm )
Figure 6. Temperature and energy confinement for
half-field operation in A.lcator C.
While a saturation of with rising density has been observed in
many previous tokamak experiments, notably in ISX, and has been interpreted
in terms of neoclassical ion heat transport, the present Alcator numbers
would seem to stretch this hypothesis. The Alcator croup regards the satu-
ration phenomenon as perhaps arising from heavv-ion radiation or from a lack
of optimization, of the discharge conditions. Extensive new experimental in-
formation from Alcator c will soon be forthcoming, with the introduction of
boiometric scans end higher-current operation. Meanwhile, the reformulation
of tokamak transport theory would clearly be premature.
III. THE PDX DEVIDE
The Polo1'dal Divertor Experiment [5] at Princeton (Fig. 7) has been op-
erated initially as a tokamak with ordinary limiters — made of titanium,
like the rest of the plasma environment in PDX. The PDX device has been
tested up to its full ratings (BT = 25 kG, I - 500 kA). Typical operating
parameters have been: R = 142 cm, a = 40 cm, BT = 20 kG, I = 360 kA. At
ne = 2 -lO15 cm-3, PDX has obtained Te(0) = 1.4 keV, <0) = 0.6 keV, and
te - 30 msec (cf. Fig. 8) .
The effective resistivity Zn is seen to be quite close to unity.
Spectj oscopic and x-ray data are in fairly good agreement with the resis-
tivicy results. The main contributors to tne Z-er.hancement appear to be
oxygen and titanium. Solometric measurements show that, for low-density
regimes (n0 - 2 • 10l3 cm-3), about half the input power of 450 kW is radi-
ated by impurities; the most important radiator is titanium.
Operation with the full PDX divertor system, is scheduled to begin dur-
ing the next month. Neutral-bean heating at 6 MW (a joint project of FFPL
and 0R.nl; will begin in early 1980, and will put the efficacy of the poloidal
divertor concept to its critical test.
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Furth, H.P. US tokamak research, article, October 1, 1979; New Jersey. (https://digital.library.unt.edu/ark:/67531/metadc1098234/m1/7/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.