WHAT DID THE 2010 EARLY CAREER AWARD ALLOW YOU TO DO?
Magnetic plasma turbulence is pervasive in astrophysical systems such as the interstellar medium, the solar wind and solar corona, and magnetospheres of planets. We don’t experience this magnetic turbulence in our everyday life as oceans and atmosphere are not magnetized. Our studies of magnetic plasma turbulence, therefore, rely on observations, numerical simulations, analytic modeling, and where possible, specially designed laboratory experiments. Plasma turbulence is a very complex phenomenon, combining a fluid-like behavior at large scales and a particle-like behavior at small scales. It can sustain strong electric currents that interact with magnetic fields.
The Early Career Award allowed me to establish a research group (consisting of postdoctoral researchers and students) that investigated the distribution of turbulent energy across the energy spectrum and the structures formed by turbulence. In addition to vortices (also common in the Earth atmosphere), magnetic turbulence creates intense sheared structures and magnetic current sheets, where magnetic-field lines break and reconnect and a lot of energy dissipates.
Plasma turbulence can not only diffuse but also amplify magnetic energy through the so-called magnetic dynamo action. This is the mechanism that sustains magnetic fields in planets and stars. We have also studied the dynamo processes in our project.
The program started by this project allowed us to address important questions in space physics (the solar wind, solar corona, earth magnetosheath), and astrophysics (accretion disks, molecular clouds, interstellar medium). Some of the new projects that emerged from this research are currently supported by grants from NASA and the National Science Foundation.
ABOUT:
Stanislav Boldyrev is a professor in the Department of Physics at the University of Wisconsin-Madison.
SUPPORTING THE DOE SC MISSION:
The Early Career Award program provides financial support that is foundational to young scientists, freeing them to focus on executing their research goals. The development of outstanding scientists early in their careers is of paramount importance to the Department of Energy Office of Science. By investing in the next generation of researchers, the Office of Science champions lifelong careers in discovery science.
For more information, please go to the Early Career Research Program.
THE 2010 PROJECT ABSTRACT:
Scaling Laws in Magnetized Plasma Turbulence
The objective of this research is to develop new analytic approaches, conduct numerical simulations with unprecedented resolution, and train students to carry out a comprehensive study of parameterâscalable regimes of magnetizedâplasma turbulence. Plasma is a dynamically rich and technologically potent state of matter, beyond solid, liquid, and gas. A distinguishing property of plasma is its sensitivity throughout its volume to perturbations in density or velocity even in a small region. When embedded in an ambient magnetic field, the plasma can be sensitive also to perturbations in the magnetic field. Depending on the size of the plasma, this collective behavior can take place over lengths as small as a few centimeters, e.g., in laboratories, and as large as thousands of light years, e.g., in astronomy. Through the power of equations that express scaled relationships of parameters, a single mathematical model can predict the properties and dynamics of phenomena associated with almost any size and parameter value of the plasma. The magnetohydrodynamics (MHD) model is often invoked for this purpose because plasma behaves like an electrically conducting fluid embedded in a magnetic field. This model involves details, the appropriateness and microscopic level of which need to be customized for the specific laboratory or astronomical application, which are not always agreed upon by scientists and won't be until experiments can validate such details. In the meantime, the theories that describe these details sometimes lead to contradicting predictions, as the theories are typically empirical or phenomenological. Weak MHD turbulence, strong MHD turbulence, and magnetic dynamo action will be emphasized in the study.
RESOURCES:
S. Boldyrev and J.C. Perez, “Spectrum of kinetic-Alfvén turbulence.” Astrophys. J. 758, L44 (2012). [DOI: 10.1088/2041-8205/758/2/L44]
C.H.K. Chen, S. Boldyrev, Q. Xia, and J.C. Perez, “Nature of subproton scale turbulence in the solar wind,” Phys. Re. Lett. 110, 225002 (2013). [DOI: 10.1103/PhysRevLett.110.225002]
V. Zhdankin, S. Boldyrev, J.C. Perez, and S.M. Tobias, “Energy dissipation in magnetohydrodynamic turbulence: Coherent structures or ‘nanoflares’?” Astrophys. J. 795, 127 (2014). [DOI: 10.1088/0004-637X/795/2/127]
Additional profiles of the 2010 Early Career Award winners can be found at https://www.energy.gov/science/listings/early-career-program.
The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit https://www.energy.gov/science/office-science.
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