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Scaling law: Difference between revisions
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A scaling law is an engineering tool to predict the value of a system variable as a function of some other significant variables. | A scaling law is an engineering tool to predict the value of a system variable as a function of some other significant variables. | ||
<ref>O.J.W.F. Kardaun, ''Classical methods of statistics: with applications in fusion-oriented plasma physics'', Springer Science & Business (2005) ISBN 3540211152</ref> | <ref>O.J.W.F. Kardaun, ''Classical methods of statistics: with applications in fusion-oriented plasma physics'', Springer Science & Business (2005) {{ISBN|3540211152}}</ref> | ||
Their extended use in magnetic confinement physics reflects the fact that detailed transport calculations or predictions on the basis of first principles are difficult in this field. In the latter context, they are mainly used to | Their extended use in magnetic confinement physics reflects the fact that detailed transport calculations or predictions on the basis of first principles are difficult in this field. In the latter context, they are mainly used to | ||
* predict the performance of new (larger) devices, such as [[ITER]] | * predict the performance of new (larger) devices, such as [[ITER]] | ||
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By contrast, the L-mode scaling is of the Bohm type (α = 0), which suggests that transport may [[Non-diffusive transport|not be diffusive]] and not characterized by a typical scale length, i.e., it is dominated by the scale length corresponding to the machine size (non-locality). | By contrast, the L-mode scaling is of the Bohm type (α = 0), which suggests that transport may [[Non-diffusive transport|not be diffusive]] and not characterized by a typical scale length, i.e., it is dominated by the scale length corresponding to the machine size (non-locality). | ||
<ref>A. Dinklage, ''Plasma physics: confinement, transport and collective effects'', Vol. 670 of Lecture notes in physics, Springer (2005) ISBN 3540252746</ref> | <ref>A. Dinklage, ''Plasma physics: confinement, transport and collective effects'', Vol. 670 of Lecture notes in physics, Springer (2005) {{ISBN|3540252746}}</ref> | ||
One possible explanation of this behaviour is [[Self-Organised Criticality]], i.e., the self-regulation of transport by turbulence, triggered when a critical value of the gradient is exceeded. As a corollary, this mechanism might also explain the phenomenon of [[Profile consistency|profile consistency]]. | One possible explanation of this behaviour is [[Self-Organised Criticality]], i.e., the self-regulation of transport by turbulence, triggered when a critical value of the gradient is exceeded. As a corollary, this mechanism might also explain the phenomenon of [[Profile consistency|profile consistency]]. | ||