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University of Wisconsin Physics Department

Research funding includes support from:

Department of Energy

National Science Foundation

 The RFP presents robust relaxation arising from magnetic fluctuations, a process sometimes referred to as magnetic self-organization. Magnetic fluctuations strongly influence the macroscopic behavior of the RFP. The influence of magnetic fluctuations on particle and energy transport is discussed in the section Discovering the Lower Limit to Magnetic Transport .


Here we discuss other aspects of magnetic self-organization: the transport of angular momentum, the dynamo effect, magnetic reconnection, ion heating by fluctuations, the origin and role of m = 0 modes, and magnetic microturbulence. We aim to determine the mechanism responsible for the transport of angular momentum, a process that determines the plasma rotation. We are continuing our research unraveling the physics of the dynamo effect, a mechanism that determines, in part, the current density profile. Closely related to the dynamo study is our investigation of basic properties of magnetic reconnection, including two-fluid effects. The RFP displays strong self-heating of ions, an intriguing effect which to date lacks explanation. Underlying much of the self-organization in the RFP is the occurrence of m = 0 modes that appear to be a trigger for discrete self-organization events. We are continuing our efforts to understand their role and consequences. Finally, the RFP displays broadband magnetic turbulence at frequencies above those of the large-scale tearing modes. These fluctuations may offer opportunity to enhance understanding of magnetic turbulence, in genesral. The strong effect of magnetic self-organization on the performance of the RFP motivates our research in this area as part of our development of the RFP as a fusion energy source. In addition, these studies have particularly strong impact on plasma physics in general, extending to plasma astrophysics. Thus, these studies will also receive support from the new Center for Magnetic Self-Organization (CMSO) .


The University of Wisconsin is the principal investigator institution for the Center, primarily because of the presence of the MST experiment. The purpose of the Center is to study fundamental plasma physics issues, within the overall theme of magnetic self-organization, that are common to the lab and astrophysical plasmas. A key feature of the Center is that it unites laboratory and astrophysical scientists in a collaborative approach to these plasma problems. This is a remarkable opportunity for MST fusion research and a notable benefit to fusion energy outreach to other sciences. The Center research plan consists of six topics: dynamo effects, magnetic reconnection, angular momentum transport, ion heating, magnetic chaos and transport, and magnetic helicity conservation and transport. All these phenomena are strongly coupled in MST, occurring simultaneously during a sawtooth crash and likely related to magnetic fluctuations. They also occur in key astrophysical situations: dynamo field generation is ubiquitous in the universe; magnetic reconnection drives solar flares and can regulate star formation; angular momentum transport determines black hole accretion rates; and ion heating occurs in the solar wind. Thus, understanding magnetic self-organization in plasmas is crucial to unraveling puzzles in both astrophysical and laboratory plasma behavior.