103 citations · 704 across the 25 of their papers we have counts for
24 papers
Second stability region for gyrokinetics and the L-H transition
R. J. J. Mackenbach, A. Zocco, P. Helander
Using a simple circular tokamak geometry, we show the well-known `second stability region' of MHD-ballooning modes exists for linear gyrokinetics too -- whether electrostatic or el…
On the Shafranov shift in stellarators
Per Helander, Nikita Nikulsin
As first shown by Shafranov, toroidal plasmas in magnetohydrodynamic equilibrium tend to expand in major radius when the pressure is increased. Here, an average measure of the resu…
Optical analogy for stellarators: Ridges as caustics and coils as singularities
Wrick Sengupta, Stefan Buller, Rogerio Jorge +7
A common feature of most numerically optimized stellarator geometries is the presence of sharp ridges on outer flux surfaces, irrespective of the rotational transform. Despite thei…
The residual flow in well-optimized stellarators
G. G. Plunk, P. Helander
The gyrokinetic theory of the residual flow, in the electrostatic limit, is revisited, with optimized stellarators in mind. We consider general initial conditions for the problem,…
The available energy of trapped electrons and its relation to turbulent transport
R. J. J. Mackenbach, J. H. E. Proll, P. Helander
A collisionless plasma possesses a certain amount of "available energy", which is that part of the thermal energy that can be converted into field energy. Here, a calculation is pr…
Representing the boundary of stellarator plasmas
Sophia A. Henneberg, Per Helander, Michael Drevlak
In stellarator optimization studies, the boundary of the plasma is usually described by Fourier series that are not unique: several sets of Fourier coefficients describe approximat…