Abstract
Given a set of current-carrying filaments that create a magnetic field with rotating elliptical flux surfaces, we present verification calculations using the VMEC, DESC, and SPEC free-boundary magnetohydrostatic equilibrium codes for both the “vacuum” equilibrium, for which there is no plasma pressure and no plasma currents, and for a non-zero pressure, zero toroidal current equilibrium. For the vacuum case, these codes are quantitatively compared to the magnetic field produced by the coils. For the non-zero pressure case, they are compared to each other. As the stepped pressure profile used in SPEC approaches the continuous profile used in VMEC and DESC, the SPEC magnetic axis approaches the VMEC and DESC axes. To within an error given by the difference between the pressure profiles, the VMEC, DESC, and SPEC calculations give the same pressure-induced geometric shift of the magnetic axis, known as the Shafranov shift.
| Original language | English |
|---|---|
| Article number | 043906 |
| Journal | Physics of Plasmas |
| Volume | 32 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 1 2025 |
Funding
The authors dedicate this manuscript to Bob Dewar, and they thank Jim Hanson, John Schmit, and Jonathan Schilling for helpful discussions. This work was supported by the U.S. Department of Energy (Contract Nos. DE-AC02-09CH1146, DE-AC02-09CH11466, and DESC0022005, and Field Work Proposal No. 1019) and by the Simons Foundation/SFARI (Grant No. 560651, A.B. and D.P.). The United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.