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Reversed Field Pinches (RFP TCP)


Identifying common research challenges

The RFP TCP shares instrumentation and carries out joint experiments to develop theories and models of the physics phenomenon of reversed-field pinches (RFP) and related technologies. Collaborative activities and a joint workshop with scientists researching the stellarator-heliotron concept of fusion reactors identified common research grounds such as three-dimensional (3D) computational tools. 

Studying the reversed-field pinch through 3D imaging provides insights for the design of fusion technologies (shown here on the EXTRAP T2-R, Sweden).*

The most highly developed approach to fusion power, the tokamak, confines hot plasmas through the use of large, superconducting magnets that create a powerful magnetic field. However, the magnetic coils are located outside of the chamber, creating physics and engineering challenges that must be overcome. In the RFP approach, the current in the plasma generates almost all of the magnetic field, heating the plasma and reducing the magnetic field that must be applied from the outside. This increases efficiency, yielding a larger fraction of kinetic energy in the plasma relative to the magnetic energy in the magnets. 

As a close relative to the tokamak and stellarator configurations, RFP research advances fusion science and engineering while resolving key challenges specific to fusion reactors based on this concept. Knowledge gained from physics research of the RFP phenomena bridges the gap between tokamaks and stellarators by developing predictive models for achieving and maintaining fusion plasma. 

There are four RFP devices worldwide. Therefore close collaboration enables these fusion research laboratories to leverage scarce resources by sharing experimental results during periodic workshops. In September 2013, a first joint workshop was organised between the RFP TCP and the stellarator heliotron (SH) research communities. This was an important first step towards aligning research goals and mutually benefitting from experimental results in both types of fusion reactors. The workshop underlined that despite differences in the configurations among the devices, the magnetic confinement community shares several 3D are important issues. 

Both SH and RFP research communities gain knowledge from sharing three-dimensional (3D) computational tools. Therefore (3D) geometry was a recurring theme of the workshop. One of the most critical common issues is the role of fast ions and their confinement with many fusion-generated alpha particles (high-speed helium atoms). Another important issue highlighted was the need to remove the helium “ash” from the plasma in order to maintain the fusion reaction. 

Other common issues discussed include power exhaust, stability control, plasma confinement, closer integration of the optimisation of physics performance and engineering design issues, and critical evaluation and testing of models of particle, momentum and energy transport, and development of diagnostics. 

These are some of the topics discussed at the workshop that provided a valuable opportunity to understand more clearly commonalities and differences between the SH and RFP theoretical approaches to technology for nuclear fusion, and demonstrated the value of exploring common research grounds. Presentations and the workshop summary are available upon request. 

* Graphic courtesy of Erik Olofsson, General Atomics


  • Co-ordinated experiments on RFP fusion devices:
    • EXTRAP T2-R (Sweden)
    • Madison Symmetric Torus (MST) (United States)
    • Reversed Field Experiment (RFX) (Italy)
    • Reversed Field Pinch of Low Aspect Ration (Japan)


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For more information: The RFP TCP website is under development

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