Abstract
We report the neoclassical tearing mode (NTM) stabilization experimental results by injection of the electron cyclotron (EC) beam in KSTAR, along with its analysis using integrated modelling. We utilized a minimum seeking feedback control algorithm combined with real-time estimate of the island width growth rate. In this KSTAR experiment, deleterious instability is intentionally induced and stabilized by 700 kW of EC injection, with the launching angle determined by the minimum seeking controller. Mode analyses identified nature of the instability, with measured amplitude of approximately 15 G, as a 2/1 NTM. As a result, the island width decreased substantially towards the end of the experiment, followed by the recovery of plasma performance. To analyze how the NTM is stabilized, we performed integrated modelling with TRIASSIC using the experimental plasma pressure and computed plasma current contributed from Ohmic, neoclassical, and EC driven effects. By calculating various mechanisms acting on the island width growth with a simplified modified Rutherford equation, we observed that the 2/1 NTM is stabilized by EC injection.
| Original language | English (US) |
|---|---|
| Article number | 114850 |
| Journal | Fusion Engineering and Design |
| Volume | 212 |
| DOIs | |
| State | Published - Mar 2025 |
| Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Nuclear Energy and Engineering
- General Materials Science
- Mechanical Engineering
Keywords
- ECCD
- KSTAR
- Minimum seeking algorithm
- Modified Rutherford equation
- NTM
- Tokamak control