Confinement scaling laws such as IPB98(y, 2) are widely used to extrapolate the performance of present tokamaks to next-step devices such as ITER or DEMO. The thermal energy of the plasma (W _th), which is used to determine the energy confinement time for most scaling laws, is difficult to measure, due to the sizeable uncertainties in the experimental kinetic profiles. The common approach in the tokamak community is to derive W _th as the difference between the measured magnetohydrodynamic (MHD) energy and some simulation-based estimate of the fast ion energy W _fi. In H-mode plasmas W _fi can be as high as W _th, in presence of neutral beam injection (NBI) or ion cyclotron radio frequency heating (ICRF), therefore an accurate assessment of W _fi is crucial to have a somewhat reliable H-factor, regardless of the power-scaling of a given scaling law. In this paper we aim at evaluating the current approach to estimate W _fi, by comparing its predictions with a wide database of calculations using validated NBI codes. Systematic deviations and trends, as well as statistical scatter are discussed. We use a comprehensive database of AUG H-mode deuterium plasmas, with significant variations of plasma current, NBI power and plasma density. We neglect thereby the fast-ion losses caused by MHD modes and the synergy effect between NBI and ICRF. A new approach is proposed based on the newly developed fast NBI code RABBIT.

诸如IPB98（y，2）之类的限制缩放定律被广泛用于将当前托卡马克的性能外推至诸如ITER或DEMO之类的下一步设备。由于实验动力学过程中存在很大的不确定性，因此很难测量用于确定大多数比例定律的能量限制时间的等离子体热能（W _th）。在托卡马克社区的常见方法是派生W¯¯ _个作为测量磁流体（MHD）能量和快离子能量的一些基于模拟的估计之间的差W¯¯ _音响。在H模式等离子体中，W _fi可以高达W _th因此，在存在中性束注入（NBI）或离子回旋加速器射频加热（IC​​RF）的情况下，无论给定定标定律的功率定标如何，准确评估W _fi都是至关重要的，因为它具有一定程度的可靠H因子。在本文中，我们旨在评估当前的估计W _{fi的方法。}，通过使用经过验证的NBI代码将其预测结果与广泛的计算数据库进行比较。讨论了系统偏差和趋势以及统计分散。我们使用AUG H型氘等离子体的综合数据库，其中等离子体电流，NBI功率和等离子体密度有很大的变化。因此，我们忽略了由MHD模式引起的快速离子损失以及NBI和ICRF之间的协同效应。在新近开发的快速NBI码RABBIT的基础上，提出了一种新的方法。