# The Impact of Collisionality, FLR and Parallel Closure Effects on Instabilities in the Tomakak Pedestal: Numerical Studies with the NIMROD code

## TL;DR

This study uses the NIMROD extended-MHD code to analyze how collisionality, FLR, and parallel closure effects influence plasma instabilities in the tokamak pedestal, comparing results with ideal-MHD models and analytic calculations.

## Contribution

It provides a detailed numerical verification of NIMROD against the ELITE code and explores the effects of various physical factors on plasma stability in the tokamak pedestal.

## Key findings

- Resistive effects are destabilizing.
- Finite-Larmor-radius effects are stabilizing.
- Analytic models overpredict destabilization and stabilization.

## Abstract

The extended-MHD NIMROD code [C.R. Sovinec and J.R. King, J. Comput. Phys. 229, 5803 (2010)] is verified against the ideal-MHD ELITE code [H.R. Wilson et al. Phys. Plasmas 9, 1277 (2002)] on a diverted tokamak discharge. When the NIMROD model complexity is increased incrementally, resistive and first-order finite-Larmour radius effects are destabilizing and stabilizing, respectively. The full result is compared to local analytic calculations which are found to overpredict both the resistive destabilization and drift stabilization in comparison to the NIMROD computations.