# Effects of resonant magnetic perturbation on locked mode of neo-classical tearing modes

## TL;DR

This study numerically investigates how externally applied resonant magnetic perturbations influence the behavior of locked neo-classical tearing modes, revealing different regimes and critical thresholds depending on plasma parameters.

## Contribution

It introduces a detailed numerical analysis of RMP effects on NTM locked modes, identifying new regimes and dependencies on plasma parameters.

## Key findings

- Identification of three regimes: suppression, SLI, and BLI.
- Discovery of a new oscillation regime at high bootstrap current fractions.
- Determination of critical RMP values and their parameter dependencies.

## Abstract

Effects of externally applied resonant magnetic perturbation (RMP) on the locked mode of neo-classical tearing mode (NTM) are numerically investigated by means of a set of reduced magnetohydrodynamic equations. It is found that for a small bootstrap current fraction, three regimes, namely slight suppression regime, small locked island (SLI) regime and big locked island (BLI) regime, are discovered with the increase of RMP strength. For a much higher bootstrap current fraction, however, a new oscillation regime appears instead of the SLI regime, although the other regimes still remain. The physical process in each regime is analyzed in detail based on the phase difference between NTM and RMP. Moreover, the critical values of RMP in both SLI and BLI regimes are obtained, and their dependence on key plasma parameters is discussed as well.