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The FTU tokamak (R = 0.93 m; a = 0.3 m; B(T) = 8 T; I(p) values up to 1.6 MA) has operated essentially in the ohmic regime with both H(2), D(2) and He filling gas. Most of H(2) and D(2) data, if plotted in the traditional Hugill plot, show an almost q-independent density limit, corresponding to nR/B = 2.3 x 1.0 E19/Wb. This reproduces the FT density limit at q = 6.7 while it is a factor of 2 lower at q = 3.3. At the latter q value, the FT limit has been fully recovered in He. Peaked density profile discharges reach a higher nRq/B parameter, thus supporting the idea that the limiting density is that of the edge. The operational limit can be expressed by n is approximately equal to the square root of P(OH) at r = -18 cm, as expected from a balance between ohmic input and edge radiated power.

Additional information

Authors: FRIGIONE D, ENEA, Centro Ricerche Energia Frascati, Roma (IT);PIERONI L, ENEA, Centro Ricerche Energia Frascati, Roma (IT)
Bibliographic Reference: Report: RT/NUCL/92/40 EN (1993) 19 pp.
Availability: Available from Servizio Studi e Documentazione, ENEA, Centro Ricerche Energia Frascati, C.P. 65-00044 Frascati, Roma (IT)
Record Number: 199311115 / Last updated on: 1994-11-29
Original language: en
Available languages: en