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Anomalous transport: Difference between revisions
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The difference between actual transport and the Neoclassical expectation is called "[[:Wiktionary:anomaly|anomalous]]" transport. | The difference between actual transport and the Neoclassical expectation is called "[[:Wiktionary:anomaly|anomalous]]" transport. | ||
It is generally assumed that the anomalous component of transport is generated by turbulence driven by micro-instabilities. | It is generally assumed that the anomalous component of transport is generated by turbulence driven by micro-instabilities. | ||
<ref>J.P. Freidberg, ''Plasma physics and fusion energy'', Cambridge University Press (2007) ISBN 0521851076</ref> | <ref name="Freidberg">J.P. Freidberg, ''Plasma physics and fusion energy'', Cambridge University Press (2007) ISBN 0521851076</ref> | ||
== How important is turbulence? == | == How important is turbulence? == | ||
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An important argument suggesting that anomalous transport is important to the degree that it often dominates the total transport is the [[Scaling law|scaling]] of transport with heating power and machine size. The phenomenon of [[Scaling law|power degradation]], universally observed in all devices, is an indication that standard transport theories are inadequate to explain all transport, since these would not predict power degradation. | An important argument suggesting that anomalous transport is important to the degree that it often dominates the total transport is the [[Scaling law|scaling]] of transport with heating power and machine size. The phenomenon of [[Scaling law|power degradation]], universally observed in all devices, is an indication that standard transport theories are inadequate to explain all transport, since these would not predict power degradation. | ||
Following Freidberg, | Following Freidberg, | ||
<ref | <ref name="Freidberg" /> | ||
the cited [[Scaling law|scaling laws]] can be rewritten in terms of the temperature dependence (eliminating the heating power dependence). | the cited [[Scaling law|scaling laws]] can be rewritten in terms of the temperature dependence (eliminating the heating power dependence). | ||
Then, classical and neoclassical estimates would predict that the confinement increases with ''T'' (namely: ''τ<sub>E</sub>'' ∝ ''T<sup>0.5</sup>'', associated with collisionality). | Then, classical and neoclassical estimates would predict that the confinement increases with ''T'' (namely: ''τ<sub>E</sub>'' ∝ ''T<sup>0.5</sup>'', associated with collisionality). | ||