Unlike most naturally-occurring plasmas (e.g., the Solar wind), tokamak plasmas are extremely

Tokamak plasmas are sometimes terminated by violent events known as

The overwhelming majority of disruptions that are not caused by crossing ideal stability boundaries are associated with

Tearing modes in tokamak plasma are very poorly described by conventional single-fluid resistive-MHD, because of the relatively low collisionality of such plasmas, combined with the significantly different drift velocities of the various plasma species. Tearing modes are also very poorly described by linear analysis, which becomes invalid as soon as the radial widths of the magnetic island chains at the various resonant surfaces exceed the (very narrow) linear layer widths.

Unless something goes seriously wrong, the widths of magnetic island chains in tokamak plasmas evolve

Tearing modes in tokamak plasmas usually

Error-fields are small (typically a few Gauss) non-axisymmetric perturbations in the equilibrium magnetic field generated by field-coil misalignements. Error-fields are sometimes deliberately applied to tokamak plasmas (by running currents in external field coils) in order to control an annoying instability known as an

Modeling the dynamics of tearing modes in tokamak plasmas, in the presence of a resistive wall, error-fields, and RMPs, is very challenging, because it inevitably involves modeling the discharge for tens, or even hundereds, of

- This presentation outlines the basic philosophy of the EPEC code.
- The EPEC code has been implemented as a module in the OMFIT integrated modeling framework.
- The EPEC source code can be found here. (The
*development*branch is currently the relevant branch.) - The OMFIT source code can be found here. (The
*EPEC_refactored*branch is currently the relevant branch.)

- Complete description of the physics model implemented in the EPEC code [PDF].
- Details of the algorithms employed in the FLUX submodule [PDF].
- Details of the cylindrical tearing mode analysis used in the FLUX submodule to determine the parameters Delta', Sigma', Delta_w, and Sigma_w. [PDF].
- Details of the algorithms employed in the NEOCLASSICAL submodule [PDF].
- Details of the algorithms employed in the PHASE submodule [PDF].
- Details of the algorithms employed in the RESCALE submodule [PDF].

- R. Fitzpatrick, R. Maingi, J.-K. Park, and S. Sabbagh
*Theoretical investigation of the triggering of neoclassical tearing modes by transient magnetic perturbations in NSTX*

Phys. Plasmas**30**, 072505 (2023). [PDF] - R. Fitzpatrick, SangKyeun Kim, and Jaehyun Lee,
*Modeling of q95 windows for the suppression of edge localized modes by resonant magnetic perturbations in the KSTAR tokamak*, Phys. Plasmas**28**, 082511 (2021) [PDF]. - R. Fitzpatrick,
*Further modeling of q95 windows for the suppression of edge localized modes by resonant magnetic perturbations in the DIII-D tokamak*, Phys. Plasmas**28**, 022503 (2021) [PDF]. - R. Fitzpatrick,
*Modeling q95 windows for the suppression of edge localized modes by resonant magnetic perturbations in the DIII-D tokamak*. Phys. Plasmas**27**, 102511 (2020) [PDF]. - R. Fitzpatrick, and A.O. Nelson,
*An improved theory of the response of DIII-D H-mode discharges to static resonant magnetic perturbations and its implications for the suppression of edge localized modes*, Phys. Plasmas**27**, 072501 (2020) [PDF].

Richard Fitzpatrick