Abstract
A two-fold analysis of electromagnetic core tokamak instabilities in the framework of the gyrokinetic theory is presented. First principle theoretical foundations of the gyrokinetic theory are used to explain and justify the numerical results obtained with the global electromagnetic particle-in-cell code Orb5 whose model is derived from the Lagrangian formalism. The energy conservation law corresponding to the Orb5 model is derived from the Noether theorem and implemented in the code as a diagnostics for energy balance and conservation verification. An additional Noether theorem based diagnostics is implemented in order to analyse destabilising mechanisms for the electrostatic and the electromagnetic ion temperature gradient instabilities in the core region of the tokamak. The transition towards the Kinetic Ballooning Modes at high electromagnetic β is also investigated.
Highlights
First principle theoretical foundations of the gyrokinetic theory are used to explain and justify the numerical results obtained with the global electromagnetic particle-in-cell code ORB5 whose model is derived from the Lagrangian formalism
The energy conservation law corresponding to the ORB5 model is derived from the Noether theorem and implemented in the code as a diagnostics for energy balance and conservation verification
An additional Noether theorem based diagnostics is implemented in order to analyse destabilising mechanisms for the electrostatic and the electromagnetic ion temperature gradient instabilities in the core region of the tokamak
Summary
Magnetised fusion plasmas represent a paradigmatic example of out-of-equilibrium systems, in which turbulence is ubiquitous. This omnipresence originates from the concept of magnetic fusion itself: Bringing the mix of hydrogen isotopes into the confinement mode implies by construction the existence of strong spatial gradients. As the plasma pressure increases the inductive electric field from the fluctuating magnetic field δB⊥ begins to cancel part of the electrostatic component of the parallel electric field This cancellation reduces the energy transfer rate á j E ñ and reduces the growth rate of instability. In order to provide a better understanding of the global electromagnetic GK simulations, we present an analysis of the instability mechanisms by performing global linear electromagnetic simulations with the particle-in-cell code ORB5.
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