中文摘要：

In this paper,a mechanism about the variability of the L-H transition power threshold PL-His proposed which is based on the ion orbit losses.Only in the edge where there are enough ion orbit losses and the negative radial electric field Eris high enough can the H-mode be triggered.The ion orbit losses are determined by the ion in the loss region under certain edge conditions.For different mass A and different charge Z,the critical loss energy E∝Z2/A in the loss region.In H and D charges,because the D+loss region is larger than H+,it can be deduced that the PL-Hof H is larger than that of D.In a4He discharge,experiment finds there exist a considerable number of4He1+in the plasma edge.The actual ion orbit losses are determined by the mixing ratio of4He1+and4He2+.The4He1+loss region is larger than that of4He2+,and the loss region of D+interposes between4He1+and4He2+.Different4He1+content can cause the edge ion losses in a4He discharge to be greater than,less than or equal to that in a D discharge.So a4He discharge can exhibit multiple experimental phenomena in the PL-H.

英文摘要：

In this paper, a mechanism about the variability of the L-H transition power thresh- old PL-H is proposed which is based on the ion orbit losses. Only in the edge where there are enough ion orbit losses and the negative radial electric field Er is high enough can the H-mode be triggered. The ion orbit losses are determined by the ion in the loss region under certain edge conditions. For different mass A and different charge Z, the critical loss energy E Z2/A in the loss region. In H and D charges, because the D＋ loss region is larger than H＋, it can be deduced that the PL-H of H is larger than that of D. In a 4He discharge, experiment finds there exist a considerable number of 4He1＋ in the plasma edge. The actual ion orbit losses are determined by the mixing ratio of a He1＋ and 4He2＋. The 4He1＋ loss region is larger than that of 4He2＋, and the loss region of D＋ interposes between 4He1＋ and 4He2＋. Different 4He1＋ content can cause the edge ion losses in a 4He discharge to be greater than, less than or equal to that in a D discharge. So a 4He discharge can exhibit multiple experimental phenomena in the PL-H.