MEASUREMENT OF THE RADIAL ELECTRIC-FIELD IN THE ASDEX TOKAMAK
MEASUREMENT OF THE RADIAL ELECTRIC-FIELD IN THE ASDEX TOKAMAK
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DOI：
10.1088/0029-5515/32/7/i09
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发表时间：
1992-07-01
期刊：
影响因子：
3.3
通讯作者：
HOFMANN, JV
中科院分区：
文献类型：
--
作者：
FIELD, AR;FUSSMANN, G;HOFMANN, JV
通过测量低z杂质离子（He II, B IV, C III）的漂移速度，可以估计等离子体外围的径向电场E(r)。漂移速度由沿相反观测方向观测到的可见线发射的差分多普勒频移确定。详细讨论了测量原理，包括抗磁漂移的贡献，以及激励率的径向梯度和沿视线积分的影响。测量到的瞄准线平均漂移速度会受到E(r)剖面的位置和形状的强烈影响，特别是当在其他托卡马克上测量到的E(r)剖面定位在分离矩阵内的一个狭窄区域时。假设径向剖面不变而估计的E(r)值低估了局部最大值。然而，在H*相，biv离子在电子反磁漂移方向上的高视线平均垂直漂移速度至少为15 km/s。由此推断，在等离子体边缘区域存在至少25 kV/m的强负径向电场。用合适的新古典理论计算的硼离子极向漂移速度值与测量值方向一致。但是，计算出的瞄准线平均值比实测值要小得多。这加强了一个强负径向电场存在于h模分离矩阵内的结论。
Estimates of the radial electric field E(r) at the plasma periphery are obtained by measuring the drift velocities of low-Z impurity ions (He II, B IV, C III). The drift velocities are determined from the differential Doppler shift of visible line emission observed along opposite viewing directions. The principle of the measurement, including contributions from the diamagnetic drift, as well as radial gradients in the excitation rate and the effect of integrating along the line of sight are discussed in detail. The measured line of sight averaged drift velocities can be strongly influenced by the location ad shape of the E(r) profile, especially if, as measured on other tokamaks, it is localized to a narrow region just within the separatrix. Values of E(r) estimated by assuming a constant radial profile underestimate maximum local values. During the H*-phase, however, high line of sight averaged perpendicular drift velocities of the B IV ions of a least 15 km/s in the electron diamagnetic drift direction are observed. From this, the presence of a strong negative radial electric field of at least 25 kV/m in the plasma edge region is inferred. Values of the B IV ion poloidal drift velocity calculated from an appropriate neoclassical theory are in the same direction as those measured. However, the calculated line of sight averaged values are much smaller than the measured ones. This reinforces the conclusion that a strong negative radial electric field is present just within the separatrix during the H-mode.