Plasma self-organization in a magnetic confinement system: Plasmas in fusion research for energy production offer intriguing challenges for physicists, involving the difficulties often summarized under the subject of "complex systems". In this presentation we provide a survey of the advancements and open issues developed in the Reversed Field Pinch activity in Padova, at Consorzio RFX. The RFP configuration relies basically on currents flowing in the plasma itself in order to produce both the confining magnetic field and plasma heating. This character can be used to describe the difference with respect to the leading toroidal magnetic configurations in present fusion research, the Tokamak and the Stellarator. This character is also at the basis of a phase transition which sees the system living either in a magnetically disordered phase or developing a helical (kinked) pattern, which can favor the formation of confining ordered structures. The transition to similar ordered helical regimes provides a possible path to the development of confinement system based on plasma self organization. The helical self-organization process was firstly anticipated in magneto-fluid modeling since the 90ties (3D nonlinear numerical simulations), and then observed in larger experiments, in particular in RFX-mod, when pushing plasma currents to higher values: experimentally, such a helical state corresponds to improved plasma confinement. Present research focuses on how to best exploit the "natural" tendency toward helical regimes. On the one hand, feedback techniques applied to a net of magnetic coils at the plasma boundary are considered in order to comply with or to stimulate the process. On the other hand, techniques to treat the plasma facing materials in order to avoid too dense and cold plasmas at the edge are under development. The integration of different disciplines (physics of complex systems, engineering, material science) and activities (theory and numerical modeling, experimental phenomenology and diagnostics) is part of the challenge in our research activity.
Plasma self-organization in a magnetic confinement system
Susanna Cappello;D Bonfiglio;
2013
Abstract
Plasma self-organization in a magnetic confinement system: Plasmas in fusion research for energy production offer intriguing challenges for physicists, involving the difficulties often summarized under the subject of "complex systems". In this presentation we provide a survey of the advancements and open issues developed in the Reversed Field Pinch activity in Padova, at Consorzio RFX. The RFP configuration relies basically on currents flowing in the plasma itself in order to produce both the confining magnetic field and plasma heating. This character can be used to describe the difference with respect to the leading toroidal magnetic configurations in present fusion research, the Tokamak and the Stellarator. This character is also at the basis of a phase transition which sees the system living either in a magnetically disordered phase or developing a helical (kinked) pattern, which can favor the formation of confining ordered structures. The transition to similar ordered helical regimes provides a possible path to the development of confinement system based on plasma self organization. The helical self-organization process was firstly anticipated in magneto-fluid modeling since the 90ties (3D nonlinear numerical simulations), and then observed in larger experiments, in particular in RFX-mod, when pushing plasma currents to higher values: experimentally, such a helical state corresponds to improved plasma confinement. Present research focuses on how to best exploit the "natural" tendency toward helical regimes. On the one hand, feedback techniques applied to a net of magnetic coils at the plasma boundary are considered in order to comply with or to stimulate the process. On the other hand, techniques to treat the plasma facing materials in order to avoid too dense and cold plasmas at the edge are under development. The integration of different disciplines (physics of complex systems, engineering, material science) and activities (theory and numerical modeling, experimental phenomenology and diagnostics) is part of the challenge in our research activity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
