Turbulence in Full-f and Full-k

Turbulence is a common phenomenon in flows of fluids and gases. Accurate and meaningful models and computer simulations of turbulent processes are required, both for the understanding of natural flows such as in weather dynamics, and for development and optimisation of numerous technical applications. In gases at very high temperatures, the electrons can detach from the atoms, and such an ionised gas is called a plasma. Plasma is the matter, of which the sun and all the stars are made, and for many technical applications plasmas are confined by magnetic fields. A promising potential future technological application is the development of fusion energy by employing hundreds of million degrees hot, magnetised plasmas. Large temperature differences in fusion plasmas can cause fierce and unfavourable turbulent flows and transport losses. An improved understanding of turbulence and its physics basis in plasmas by experiments and according theoretical models is thus also an important task in fusion research. Previous models and computer simulations of turbulence in hot magnetised plasmas have mostly used efficient approximations and simplifications, such as a limitation to small amplitudes or to certain length scales of the turbulent vortices. However, especially at the edge of fusion plasmas turbulent structures with large amplitudes are encountered. Further, some essential physical interaction mechanisms between turbulent vortices exist also on such scales, which were previously neglected in models for large amplitudes. Recently a novel nonlinear turbulence model for magnetised plasmas has been developed, which is applicable both for large amplitudes and for all relevant scales. In this project these new generalised models for turbulence in magnetised plasmas, accounting simultaneously for arbitrary amplitudes ("full-f") and arbitrary relevant scales ("full-k"), are going to be extended and for the first time applied on topical problems in fusion research by numerical simulations. The developments and expected results of this project are not only applicable on an improved understanding of turbulence in fusion plasmas, but also on other fundamental nonlinear phenomena in magnetised plasmas, which can be encountered in astro physics or in the laboratory for example in the form of electron-positron plasmas.

Turbulence is a common phenomenon in flows of fluids and gases. Accurate and meaningful models and computer simulations of turbulent processes are required, both for the understanding of natural flows such as in weather dynamics, and for development and optimisation of numerous technical applications. In gases at very high temperatures, the electrons can detach from the atoms, and such an ionised gas is called a plasma. Plasma is the matter, of which the sun and all the stars are made, and for many technical applications plasmas are confined by magnetic fields. A promising potential future technological application is the development of fusion energy by employing hundreds of million degrees hot, magnetised plasmas. Large temperature differences in fusion plasmas can cause fierce and unfavourable turbulent flows and transport losses. An improved understanding of turbulence and its physics basis in plasmas by experiments and according theoretical models is thus also an important task in fusion research. Previous models and computer simulations of turbulence in hot magnetised plasmas have mostly used efficient approximations and simplifications, such as a limitation to small amplitudes or to certain length scales of the turbulent vortices. However, especially at the edge of fusion plasmas turbulent structures with large amplitudes are encountered. Further, some essential physical interaction mechanisms between turbulent vortices exist also on such scales, which were previously neglected in models for large amplitudes. Recently a novel nonlinear turbulence model for magnetised plasmas has been developed, which is applicable both for large amplitudes and for all relevant scales. In this project these new generalised models for turbulence in magnetised plasmas, accounting simultaneously for arbitrary amplitudes ("full-f") and arbitrary relevant scales ("full-k"), have been extended and for the first time applied on topical problems in fusion research by numerical simulations. The developments and results of this project are not only applicable on an improved understanding of turbulence in fusion plasmas, but also on other fundamental nonlinear phenomena in magnetised plasmas, which can be encountered in astro physics or in the laboratory for example in the form of electron-positron plasmas.