Numerical Simulations of JET Discharges with the ITER-Like Wall for Different Nitrogen Seeding Scenarios

Two classes of nitrogen seeded pulses are here considered: pulses at high triangularity, high confinement with moderate gas puffing and N seeding rates and pulses at low triangularity, lower confinement with higher gas puffing and N seeding. For the high-delta pulses the power radiation fraction, frad, is normally about 0.5 while at low delta frad as high as 0.7 is achieved. For the simulations we have used COREDIV code, which self-consistently couples the plasma core with the plasma edge and the main plasma with impurities. To reproduce numerically the main experimental parameters both for the core and for the SOL plasmas different settings had to be applied to COREDIV, as the perpendicular transport and recycling in the SOL and the power deposition profile in the core. Simulations suggest that higher values for frad might be achieved with N seeding only at low density and/or higher heating power.
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