Multi-machine comparison of drift fluid dimensionless parameters

Multi-machine comparison of drift fluid dimensionless parameters

Multi-machine comparison of drift fluid dimensionless parameters 150 150 UKAEA Opendata

Multi-machine comparison of drift fluid dimensionless parameters

The behaviour of the turbulence in magnetic fusion plasmas is discussed in the framework of dimensional analysis. Three main dimensionless parameters are identified, which directly affect the adiabatic response of the plasma and hence control the electron response. They were originally introduced by Scott [B. Scott, Plasma Phys Control. Fusion, 39, 1635 (1997)] and Rogers and Drake [B.N. Rogers and J.F. Drake, Phys. Rev. Lett., 79, 229 (1997)], and represent the effect of the electromagnetic induction, collisions and electron inertia. The dimensionless parameters are then evaluated at different radial positions in four existing divertor machines (ALCATOR CMOD, ASDEX-U, JET and MAST) and in three future experiments (MAST-U, ITER and DEMO). Clear multi-machine trends, suggesting a quasi-universal behaviour of the plasma, are identified and discussed. Exploiting this quasi-universality, useful insight in the physics of the machines is obtained without complex calculations or expensive numerical simulations. In particular, the trends show a clear separation of the plasma in four distinct regions: core, edge, Scrape-Off Layer and divertor, each of them characterized by a different set of parameters which, in turn, lead to significant variation of the dominant physical mechanisms across the machine.

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09/09/2011