7 papers
Geodesic extended modes in low magnetic shear tokamaks and stellarators
Richard Nies, Felix Parra
Theories of ion-scale microinstabilities in tokamaks and stellarators typically assume that the passing electrons respond adiabatically due to their fast propagation speed. However…
Theory of zonal flow growth and propagation in toroidal geometry
Richard Nies, Felix Parra
The toroidal geometry of tokamaks and stellarators is known to play a crucial role in the linear physics of zonal flows, leading to e.g. the Rosenbluth-Hinton residual and geodesic…
Energetic-particle orbits near rational flux surfaces in stellarators: I. Passing particles
Thomas E. Foster, Felix I. Parra, Roscoe B. White +3
Recent simulations have shown that, even when the magnetic field of a stellarator possesses nested toroidal flux surfaces, the orbits of passing energetic particles can exhibit isl…
Modification of ion-temperature-gradient turbulence by impurities in stellarator plasmas
Ivan Calvo, Felix I. Parra, Hanne Thienpondt +1
Recent nonlinear gyrokinetic simulations have shown that impurities can strongly modify the turbulent heat flux in stellarator plasmas. Here, the ion-temperature-gradient (ITG) dis…
Strong gradient effects on neoclassical electron transport and the bootstrap current
Silvia Trinczek, Felix I. Parra, Peter J. Catto
Standard approaches to neoclassical theory do not extend into regions of strong gradients in tokamaks such as the pedestal and internal transport barriers. Here, we calculate the m…
Characteristics of monotonic sheaths near a wall with grazing magnetic incidence
Alessandro Geraldini, Robert J. Ewart, Stephan Brunner +1
We consider a magnetised plasma in contact with an absorbing planar wall, where the angle between the magnetic field and the wall is small, (in radians) and the syst…