@article{14,
  keywords = {Plasma Physics},
  author = {Yao Zhou and Yi-Min Huang and Allen Reiman and Amitava Bhattacharjee},
  title = {Magnetohydrodynamical equilibria with current singularities and continuous rotational transform *},
  abstract = { <p>We revisit the Hahm-Kulsrud-Taylor (HKT) problem, a classic prototype problem for studying resonant magnetic perturbations and 3D magnetohydrodynamical equilibria. We employ the boundary-layer techniques developed by Rosenbluth, Dagazian, and Rutherford (RDR) for the internal\&nbsp;m=1\&nbsp;kink instability, while addressing the subtle difference in the matching procedure for the HKT problem. Pedagogically, the essence of RDR{\textquoteright}s approach becomes more transparent in the simplified slab geometry of the HKT problem. We then compare the boundary-layer solution, which yields a "DC" current singularity at the resonant surface, to the numerical solution obtained using a flux-preserving Grad-Shafranov solver. The remarkable agreement between the solutions demonstrates the validity and universality of RDR{\textquoteright}s approach. In addition, we show that RDR{\textquoteright}s approach consistently preserves the rotational transform, which hence stays continuous, contrary to a recent claim that RDR{\textquoteright}s solution contains a discontinuity in the rotational transform.</p>
 },
  year = {2019},
  journal = {Physics of Plasmas},
  volume = {26},
  month = {02/2019},
  issn = {1089-7674},
  url = {http://dx.doi.org/10.1063/1.5068778},
  doi = {10.1063/1.5068778},
  language = {eng},
}