Göttingen 2025 – wissenschaftliches Programm

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EP: Fachverband Extraterrestrische Physik

EP 5: Near-Earth Space I & Planets and Small Bodies II

EP 5.3: Hauptvortrag

Dienstag, 1. April 2025, 16:45–17:15, ZHG005

Heliosphere as a natural laboratory of turbulence and plasma nonlinearities — •Yasuhito Narita — Institut für Theoretische Physik, Technische Universität Braunschweig, Braunschweig, Germany

Heliosphere is a spatially extended domain of the solar plasma expanding radially away from the Sun with a supersonic speed, and has a length scale of about 100 astronomical units. The heliosphere serves as the largest laboratory of turbulence to us, in which various complex and irregular motions of plasma and magnetic field can be studied in detail using in-situ spacecraft. Understanding the nonlinear processes constituting heliospheric plasma turbulence has immediate implications to various research fields in space and astrophysics: turbulent dynamo mechanism generating a large-scale magnetic field, acceleration and scattering of cosmic rays, and mass and angular momentum transfer problem particularly important in the rotating system like accretion disks. Early spacecraft measurements in 1960s hinted that the heliospheric plasma is apparently in the fully-developed turbulent state, for the energy spectrum of the magnetic field fluctuations is reminiscent of the inertial range of fluid turbulence. While a number of spacecraft observations, theoretical modelings, and numerical simulations successfully contributed to build a rough picture of plasma turbulence in the heliosphere, many questions remain still unanswered. I review recent observational studies of heliospheric turbulence focusing on the inner heliosphere such as Parker Solar Probe, Solar Orbiter, and BepiColombo cruise to Mercury, and also review critically theoretical pictures and concepts.

Keywords: turbulence; fluid and plasma nonlinearities; wave-wave interactions; wave-particle interactions; space-time structure