HL-2A装置反剪切阿尔芬本征模实验观测与模拟验证

Experimental observation and simulation verification of reverse shear Alfvén eigenmodes on HL-2A tokamak

利用AMC程序获取了不同最小安全因子(q_(min))情况下反剪切阿尔芬本征模频率(RSAE)的变化特征:当最小安全因子q_(min)>1时,RSAE频率随着q_(min)增大而增大;当q_(min)<1时,RSAE频率随着q_(min)减小而增大。这与简化RSAE色散关系给出的频率相符。在HL-2A电流爬升期间和锯齿期间分别发现了q_(min)>1和q_(min)<1情况下缓慢向上扫频的模。这些模的频率介于环向阿尔芬本征模和比压阿尔芬本征模之间,与AMC得到的RSAE模频率一致,模的径向结构由单一极向谐波组成,并且高度局域在q_(min)附近,具有典型的RSAE特征。

Using AMC program,the frequency variation characteristics of reverse shear Alfvén eigenmodes(RSAE)under different safety factors are obtained.When the minimum of q-profile q_(min)>1,the frequency of RSAE increases with the increase of q_(min),and the frequency of RSAE increases with the decrease of q_(min)when q_(min)<1,which is consistent with the frequency given by simplified RSAE dispersion relation.In HL-2 A experiment,the up-sweeping mode was found in the case of q_(min)>1 and q_(min)<1 during the current ramp-up and sawtooth phase,respectively.The frequencies of these modes are between the toroidal Alfvén eigenmodes and the beta-induced Alfvén eigenmodes,which are identical with the frequency of the RSAE modes obtained with AMC.The radial mode structure consists of a single poloidal harmonic wave and is highly localized nearby q_(min),which is the typical characteristics of RSAE.