The Study Of Neutral Beam Injection Experiments On EAST

Neutral beam injection (NBI) is an effective heating method to produce and sustain the long pulse and high performance plasma.The first4MW neutral beam injector is applied during the EAST2014summer campaign,the fruitly experimental results are impressive.The plasma temperature,density,stored energy,energy confinement time and H98Y2factor remarkably increased during Neutral Beam Injection period.The transport analysis for the discharge during the neutral beam injection on EAST is done to simulate the beam power deposition and loss,and the energy confinement performance of the target-plasma is also analyzed.In this thesis,the basic process of interaction between the neutral beam and the target-plasma is briefly introduced,the typical neutral beam injection experiments around the world are overviewed.The technical parameters and the operating condition of the first beam line for EAST are introduced.The main physical diagnostics relevant to the neutral beam injection experiment are listed.By using the NUBEAM module of the TRANSP code, the classical MW-scale neutral beam injection experiments on EAST are analyzed. The numerical simulation results show that70%-80%of the beam power is absorbed by the target-plasma,and20%-30%of the beam power is lost mainly due to the shinethrough.The non-inductive current driven by NBI is relatively inefficient because the tangential injection radius is short for the EAST-NBI.The neutral beam injection heating and current driven effect are affected by some physical discharge parameters according to a simple statistics for this EAST-NBI campaign.The increased plasma stored energy is linear correlation with the neutral beam injection power.The plasma density and energy confinement time during the NBI-heating H-mode discharge period are both higher and broader than those during the NBI-heating L-mode period.Injection of adequately energy and power neutral beam during the plasma current ramping up phase is an important beam injection plan, it can change and optimize the plasma profile,save the Volt-Seconds consumption and pre-heat the target-plasma.It is one of an advanced plasma operating scenarios.The preliminary experiment has been carried out on EAST and the remarkable pre-heating effect is observed.The heat transport analysis focused on the shinethrough loss during the low density ramping up period is appied.Based on the studies, the optimized neutral beam injection experimental plan during the ramping up phase is presented.