Transport analysis of high performance JET plasmas with optimized magnetic shear (OMS) has revealed many interesting features which cannot be explained by the existing JET empirical transport model (Erba, M., et al., Plasma Phys. Control. Fusion 39 (1997) 261). TRANSP analysis shows that transport coefficients in OMS plasmas are often reduced in the plasma core (Cottrell, G.A., et al., in Controlled Fusion and Plasma Physics (Proc. 24th Eur. Conf. Berchtesgaden, 1997), Vol. 21A,Part I, European Physical Society, Geneva (1997) 81) to the level of ion neoclassical transport. TRANSP analysis and predictive modelling with JETTO show that this region of improved confinement appears near the plasma centre and then expands outwards in a way which does not follow either the evolution of the region with the negative magnetic shear or the propagation of the region with a large shear in plasma rotation. The best agreement with experiment has been achieved by using a transport model which combines the effect of a long wavelength decoupling due to small magnetic shear with its suppression by strong rotational shear. Predictive modelling of some of the characteristic JET OMS plasmas gives quite good agreement between such a model and the experimental data.
高性能JET等离子体中的优化磁剪切（OMS）输运分析揭示了诸多现有JET经验输运模型（Erba, M., et al., Plasma Phys. Control. Fusion 39 (1997) 261）无法解释的有趣特征。TRANSP分析表明，OMS等离子体中的输运系数在等离子体芯部通常降低（Cottrell, G.A., et al., in Controlled Fusion and Plasma Physics (Proc. 24th Eur. Conf. Berchtesgaden, 1997), Vol. 21A, Part I, European Physical Society, Geneva (1997) 81）至离子新经典输运水平。TRANSP分析与JETTO预测模拟表明，这一改善约束区域出现在等离子体中心附近，随后向外扩展，其方式既不遵循负磁剪切区域的演化，也不遵循等离子体旋转大剪切区域的传播。通过采用一种结合了由于小磁剪切引起的长波长解耦效应及其被强旋转剪切抑制效应的输运模型，实验与模拟结果达到了最佳一致性。对若干特征性JET OMS等离子体的预测模拟表明，该模型与实验数据之间具有相当好的一致性。