Magnetic reconnection is usually observed in fusion plasmas, being related to the presence of resonating tearing modes and to impulsive events deeply involved in plasma selforganization. Rapid rearrangements of magneDc fluxes parDcularly characterize the plasma dynamics of thereversed-field pinch (RFP) magneDc configuraDon, which involve large plasma currents and therefore a large amount of available magneDc energy. RFPs also contain multiple reconnecDon sites associated to a variety of resonant tearing modes that eventually give rise to a stochasticmagnetic field background. Energy conversion and topological change are highly linked in the definition of reconnecDon properties. In this contribution, the phenomenology of the impulsive and periodic reconnections, associated to relaxations in high-current (~1.5 MA) plasmas of the RFX-mod device, is analyzed in detail, through an ensemble average of the data from many reconnecti on events. Spatial andtemporal scales are invoked as fundamental observables. Each relaxation event is described as a series of stages, where the locking in phase of many resonant modes initiates the reconnection process that changes the global magnetic topology [1]. We discuss other fingerprints of magnetic reconnection in RFX-mod, such as the ion heating [2] and the excitation of Alfvèn waves [3,4], as well as analogous aspects found in nonlinear visco-resistive MHD modelling [5].
Phenomenology of magnetic reconnection in the RFX-mod reversed-field pinch
Predebon I;Gobbin M;Zuin M
2023
Abstract
Magnetic reconnection is usually observed in fusion plasmas, being related to the presence of resonating tearing modes and to impulsive events deeply involved in plasma selforganization. Rapid rearrangements of magneDc fluxes parDcularly characterize the plasma dynamics of thereversed-field pinch (RFP) magneDc configuraDon, which involve large plasma currents and therefore a large amount of available magneDc energy. RFPs also contain multiple reconnecDon sites associated to a variety of resonant tearing modes that eventually give rise to a stochasticmagnetic field background. Energy conversion and topological change are highly linked in the definition of reconnecDon properties. In this contribution, the phenomenology of the impulsive and periodic reconnections, associated to relaxations in high-current (~1.5 MA) plasmas of the RFX-mod device, is analyzed in detail, through an ensemble average of the data from many reconnecti on events. Spatial andtemporal scales are invoked as fundamental observables. Each relaxation event is described as a series of stages, where the locking in phase of many resonant modes initiates the reconnection process that changes the global magnetic topology [1]. We discuss other fingerprints of magnetic reconnection in RFX-mod, such as the ion heating [2] and the excitation of Alfvèn waves [3,4], as well as analogous aspects found in nonlinear visco-resistive MHD modelling [5].I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
