Flux jamming, phase transitions and layering in turbulent magnetized plasma

Abstract

This paper discusses transport barrier formation and layering as consequences of jam formation. Extensive use is made of analogies with the theory of traffic flow in one dimension. The relation of flux jamming to motility-induced phase separation is explained. Two routes to heat flux jamming are identified. The first is due to a rollover in the heat flux-pulse size relation, that is dQT(δT)/dδT<0, and is similar to the condition of flux-gradient bistability. The second occurs when the delay time between pulse and heat flux exceeds a critical value. This does not require bistability and tends to occur near marginality. This analysis yields a quantitative estimate of the answer to the eternal question of ’how near is ”near to marginal”?’ Staircase development is shown to follow jamiton train formation. The relation of jamming of avalanches to phase transitions in drift wave-zonal flow turbulence is elucidated. The formation of outward propagating blob trains and inward propagating void trains is demonstrated. The important role of turbulence spreading is identified.

This article is part of the theme issue ‘Anti-diffusive transport and layering: from sub-cellular to astrophysical scales’.