24th IAEA Fusion Energy Conference - IAEA CN-197

EX/P6-12: Investigation of the Role of Energetic Particle in the Driving of Long-lived Saturated Internal Mode on HL-2A Tokamak

11 Oct 2012, 14:00

4h 45m

Poster Room (Area F-B)

Poster EXW - Magnetic Confinement Experiments: Wave–plasma interactions; current drive; heating; energetic particles Poster: P6

Speaker

Mr Yi Liu (China)

Description

Long-lived saturated internal mode (LLM) in HL-2A tokamak, observed during neutral beam injection (NBI) with weakly reversed or broad low magnetic shear, is considered as a pressure-gradient driven MHD mode triggered by energetic particles. When the LLM occurs, a reduction in the electron density and the plasma stored energy, and fast ion losses are usually observed. The observed LLM appears with the safety factor profile has a weak shear in a broad range with qmin around unity. The ideal interchange can become marginal stable due to the weak magnetic shear if q = 1- qmin reaches a critical value, then it can be excited by the energetic particles during NBI. In HL-2A experiments, it is observed that LLMs can be suppressed by electron cyclotron resonant heating (ECRH), and by applying supersonic molecular beam injection (SMBI) or cluster jet injection (CJI) effectively. The control of LLMs may also be related to the change of q or the pressure profile induced by the local heating or fuelling.

Country or International Organization of Primary Author

China

Collaboration (if applicable, e.g., International Tokamak Physics Activities)

School of Physics and Optoelectronic Technology