A series of neon seeded JET ELMy H-mode pulses is considered from the modeling as well as from the experimental point of view. For two different Ne seeding rates and two different D puffing gas levels the heating power, P-heat, is in the range 22-29.5 MW. The main focus is on the numerical reconstruction of the total radiated power (which mostly depends on the W concentration) and its distribution between core and divertor and of Z(eff) (which mostly depends on the Ne concentration). To model with the self-consistent code COREDIV the core and the SOL two input parameters had to be adjusted case by case: the SOL diffusivity, D-SOL, and the core impurity inward pinch, v(pinch). D-SOL had to be increased with increasing Gamma(Ne) and the level of v(pinch) had to be increased with decreasing the ELM frequency, f(ELM). Since for any given gas puffing level f(ELM) decreases with the Ne seeding rate, this might lead to a limitation in the viability of reducing the target heat load by Ne seeding at moderate Gamma(D), while keeping acceptably low Z(eff). In the considered range of temperatures and densities of the SOL, the numerical results suggest the balance between friction and thermal forces to be in favor of the frictional drag for tungsten, thus providing a W screening effect.

Simulation of JET ITER-Like Wall pulses at high neon seeding rate / Telesca, G.; Ivanova-Stanik, I.; Brezinsek, S.; Czarnecka, A.; Drewelow, P.; Giroud, C.; Huber, A.; Wiesen, S.; Wischmeier, M.; Zagórski, R.; Subba, F.. - In: NUCLEAR FUSION. - ISSN 0029-5515. - 57:12(2017). [10.1088/1741-4326/aa8381]

Simulation of JET ITER-Like Wall pulses at high neon seeding rate

Subba, F.
2017

Abstract

A series of neon seeded JET ELMy H-mode pulses is considered from the modeling as well as from the experimental point of view. For two different Ne seeding rates and two different D puffing gas levels the heating power, P-heat, is in the range 22-29.5 MW. The main focus is on the numerical reconstruction of the total radiated power (which mostly depends on the W concentration) and its distribution between core and divertor and of Z(eff) (which mostly depends on the Ne concentration). To model with the self-consistent code COREDIV the core and the SOL two input parameters had to be adjusted case by case: the SOL diffusivity, D-SOL, and the core impurity inward pinch, v(pinch). D-SOL had to be increased with increasing Gamma(Ne) and the level of v(pinch) had to be increased with decreasing the ELM frequency, f(ELM). Since for any given gas puffing level f(ELM) decreases with the Ne seeding rate, this might lead to a limitation in the viability of reducing the target heat load by Ne seeding at moderate Gamma(D), while keeping acceptably low Z(eff). In the considered range of temperatures and densities of the SOL, the numerical results suggest the balance between friction and thermal forces to be in favor of the frictional drag for tungsten, thus providing a W screening effect.
2017
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2986876