• Direct construction of optimized stellarator shapes. I. Theory in cylindrical coordinates

    Matt Landreman; Wrick Sengupta
    Journal Article

    The confinement of guiding center trajectories in a stellarator is determined by the variation of the magnetic field strength B in Boozer coordinates (r,θ,φ), but B(r,θ,φ) depends on the flux surface shape in a complicated way. Here we derive equations relating B(r,θ,φ) in Boozer coordinates and the rotational transform to the shape of flux...

  • Direct construction of optimized stellarator shapes. II. Numerical quasisymmetric solutions

    Matt Landreman; Wrick Sengupta; Gabriel G. Plunk
    Journal Article

    Quasisymmetric stellarators are appealing intellectually and as fusion reactor candidates since the guiding center particle trajectories and neoclassical transport are isomorphic to those in a tokamak, implying good confinement. Previously, quasisymmetric magnetic fields have been identified by applying black-box optimization algorithms to...

  • Optimized quasisymmetric stellarators are consistent with the Garren-Boozer construction

    Matt Landreman
    Journal Article

    Most quasisymmetric stellarators to date have been designed by numerically optimizing the plasma boundary shape to minimize symmetry-breaking Fourier modes of the magnetic field strength B. At high aspect ratio, a faster approach is to directly construct the plasma shape from the equations of quasisymmetry near the magnetic axis derived by...

  • Taylor States in Stellarators: A Fast High-order Boundary Integral Solver

    Dhairya Malhotra; Antoine Cerfon; Lise-Marie Imbert-Gérard; Michael O'Neil
    Journal Article

    We present a boundary integral equation solver for computing Taylor relaxed states in non-axisymmetric solid and shell-like toroidal geometries. The computation of Taylor states in these geometries is a key element for the calculation of stepped pressure stellarator equilibria. The integral representation of the magnetic field in this work is...