In optimized stellarators of the Wendelstein line prompt losses of fast ions in superbanana orbits are reduced through a modification of the magnetic configuration by high β (ratio of the plasma pressure to the magnetic field pressure), so that most contours of the longitudinal adiabatic invariant of locally trapped particles are closed inside the plasma volume. However, magnetic drift leads to the transformation of some of these particles into the locally passing ones and vice versa. Orbit transformation upon crossing the separatrix between locally trapped and locally passing states is accompanied by jumps in that lead to collisionless stochastic diffusion (SD), which was shown to be an important mechanism of the loss of energetic ions in the optimized Wendelstein-line stellarators (C D Beidler et al 2001 Phys. Plasmas 8 2731). The theory of SD that took into account the phase space asymmetry between locally passing particles with opposite signs of was developed in (A V Tykhyy 2018 Ukr. J. Phys. 63(6) 495). This work extends that theory to consider the effect of radial electric field E _r on SD. It is found that negative E _r of such magnitudes as those observed in W7-X and predicted in Helias reactor can mitigate SD losses from the plasma core of NBI ions in W7-X and α-particles in Helias. This loss mitigation occurs because added drift increases the range of pitch angles for which separatrices are closed inside the plasma volume, even while it increases the SD coefficient. This means that E _r can be used in addition to magnetic configuration changes for both loss mitigation and energy deposition profile optimization.

在 Wendelstein 线的优化仿星器中，通过高β（等离子体压力与磁场压力的比值）修改磁构型，可以减少超级香蕉轨道中快离子的快速损失，因此纵向绝热不变量的大多数轮廓局部捕获的粒子在等离子体体积内封闭。然而，磁漂移会导致这些粒子中的一些转化为局部通过的粒子，反之亦然。穿过局部被困状态和局部通过状态之间的分界线时的轨道变换伴随着跳跃导致无碰撞随机扩散 (SD)，这被证明是优化的 Wendelstein 线仿星器中高能离子损失的重要机制（CD Beidler等人2001 Phys. Plasmas 8 2731）。考虑到具有相反符号的局部通过粒子之间的相空间不对称性的 SD 理论在 (AV Tykhyy 2018 Ukr. J. Phys. 63 (6) 495) 中得到了发展。这项工作扩展了该理论以考虑径向电场E _r对 SD 的影响。发现负E _r 像在 W7-X 中观察到的和在 Helias 反应堆中预测的那样的数量级，可以减轻 W7-X 中 NBI 离子和Helias 中α粒子的等离子体核心的 SD 损失。这种损失减轻的发生是因为增加的漂移增加了在等离子体体积内封闭的间距角的范围，即使它增加了 SD 系数。这意味着E _r可用于减少损耗和能量沉积分布优化的磁性配置变化。