Numerical Scaling with the COREDIV Code of JET Discharges with the ITER-Like Wall.

After the code parameters have been fixed by the numerical modeling of a well diagnosed JET pulse, the electron density and the input power have been changed, resulting in 4 density scans ( 〈n_e〉 in the range 3.8 - 8.2 x 10¹⁹m^-3) at P _in = 17, 22, 27, 32 MW. At any given power level, W flux decreases with increasing 〈n_e〉 as a consequence of the decrease in T_e at the target plates. Also the W concentration in the core ( cW) decreases, but this not necessarily leads to reduced core radiation. Indeed, while at high P _in the core radiation decreases with density, at low P _in it increases. At high 〈n_e〉 the increase in the input power leads to enhanced P _radPrad, leaving, however, nearly unchanged the power radiated fraction f _rad Indeed, the increase in f _rad ^with P _in is observed only at low 〈n_e〉, up to a level of about f _rad = 0.4. These numerical results, linked to the non-linear self-consistent physics of W production and transport, suggest the best conditions are achieved when the level of the electron density is adapted to the level of the available P _in. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]