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LNF:Plasma Physics: Difference between revisions
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Understanding the physics of the isotope effect in plasma transport and confinement remains as a fundamental open question confronting the fusion community since more than 30 years of intense research with direct impact in the confinement properties of fusion D-T reactors. | Understanding the physics of the isotope effect in plasma transport and confinement remains as a fundamental open question confronting the fusion community since more than 30 years of intense research with direct impact in the confinement properties of fusion D-T reactors. | ||
Furthermore, considering the present ITER power capabilities, a reduction of the L-H power threshold ( | Furthermore, considering the present ITER power capabilities, a reduction of the L-H power threshold (<math>P_{L-H}</math>) with ion mass (D vs. H) would have great impact on ITER plasma operation scenarios. | ||
The | The <math>P_{L-H}</math> power threshold deduced from empirical scaling laws is sufficient to define the minimum power required for ITER operation. | ||
Experimental studies have shown a reduction of the L-H power threshold by about 50% when using Deuterium and He instead of Hydrogen.<ref>F. Ryter et al., 2013 Nuclear Fusion 53 (2012) 113003 </ref> | Experimental studies have shown a reduction of the L-H power threshold by about 50% when using Deuterium and He instead of Hydrogen.<ref>F. Ryter et al., 2013 Nuclear Fusion 53 (2012) 113003 </ref> | ||
Based on present ITPA scaling laws, H-mode operation is expected to be marginally feasible in H but likely in He.<ref>A. Sips et al., 25th IAEA Int. Conf. on Fusion Energy St Petersburg 2014 / EX/9-1. </ref> | Based on present ITPA scaling laws, H-mode operation is expected to be marginally feasible in H but likely in He.<ref>A. Sips et al., 25th IAEA Int. Conf. on Fusion Energy St Petersburg 2014 / EX/9-1. </ref> | ||
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''Challenges and opportunities'' | ''Challenges and opportunities'' | ||
Stellarator inter-machine studies<ref>A. Dinklage et al., Nucl. Fusion 53 (2013) 063022</ref> have shown that ion energy transport significantly affects energy confinement at medium-to-high densities ( | Stellarator inter-machine studies<ref>A. Dinklage et al., Nucl. Fusion 53 (2013) 063022</ref> have shown that ion energy transport significantly affects energy confinement at medium-to-high densities (<math>n_e > 4 x 10^{19} m^{-3}</math>). | ||
Since neoclassical transport in three-dimensional devices shows unfavourable temperature scaling, it becomes more important as the temperature is increased and the validation of local neoclassical theory at reactor-relevant conditions is needed. Extensions of the standard neoclassical theory are necessary for a better assessment of collisional transport in a stellarator reactor concept, such as non-local and non flux-surface based calculations. | Since neoclassical transport in three-dimensional devices shows unfavourable temperature scaling, it becomes more important as the temperature is increased and the validation of local neoclassical theory at reactor-relevant conditions is needed. Extensions of the standard neoclassical theory are necessary for a better assessment of collisional transport in a stellarator reactor concept, such as non-local and non flux-surface based calculations. | ||