Effect of Resonant Magnetic Perturbation Field on Energetic Ion Behavior in the Large Helical Device

A study of the resonant magnetic perturbation (RMP) effect on transit beam ion behavior is performed using the total neutron emission rate (Sn) measurement of the deuterium plasma in the Large Helical Device. We conducted no RMP field, one-half RMP field, and full RMP field discharges and compared Sn that reflects the global beam ion confinement information. It is determined that owing to the RMP field, Sn decreased by approximately 15 - 30%. Numerical calculations based on the classical confinement of beam ions were performed to investigate the bulk plasma parameter effect on Sn. The calculated Sn shows that the degradation of Sn by RMP is mainly caused by the degradation of the electron temperature owing to island formation which results in a shorter slowing down time of beam ions.