National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [11375085, 11405082, 11505092, 11475083, 11375053]; National Magnetic Confinement Fusion Science Program of China [2013GB104004, 2013GB111000, 2014GB107000, 2014GB108002]; Natural Science Foundation of Hunan Province, ChinaNatural Science Foundation of Hunan Province [2015JJ4044]