In negative hydrogen ion sources, the kinetic energy of the atoms is directly related to the negative ion yield at the caesiated converter, with a larger contribution from hot atoms. The energy distribution of hydrogen atoms is related to the formation process: either the kinetic energy release, resulting from dissociation of the hydrogen molecules or molecular ions, or the proton neutralization either in the volume or during reflection at walls. The interpretation of recent experimental measurements related to the translational energy distribution of atoms or positive ions could profit from accurate inclusion of the initial energy distribution in numerical models. In this work, we focus on the calculation of the kinetic energy release for the various dissociation channels due to electron impact on H₂ and H₂ ⁺, in the Franck-Condon and delta approximation. Since in negative ion sources non-equilibrium vibrational distributions of H₂ are found, the energy distribution of fragments is calculated for all vibrational levels. The inverse cumulative distribution functions related to the main dissociation processes are given, as well as the cumulative distributions for all dissociation channels by electron impact, for simple implementation in Monte Carlo numerical simulations. Finally, the application of the method to few cases of interest for negative ion sources is discussed.

中文翻译：

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通过电子撞击产生的 H2 和 H2 + 解离碎片的能量分布，用于应用于负离子源的数值模型

在负氢离子源中，原子的动能与铯化转换器处的负离子产量直接相关，其中热原子的贡献更大。氢原子的能量分布与形成过程有关：氢分子或分子离子解离产生的动能释放，或者在体积中或在壁反射期间的质子中和。对最近与原子或正离子的平移能量分布相关的实验测量的解释可以受益于在数值模型中准确包含初始能量分布。在这项工作中，我们重点计算在 Franck-Condon 和 delta 近似中由于电子撞击 H ₂和 H ₂ ⁺而导致的各种解离通道的动能释放。由于在负离子源中发现H ₂的非平衡振动分布，因此计算所有振动能级的碎片能量分布。给出了与主要解离过程相关的逆累积分布函数，以及电子撞击所有解离通道的累积分布，以便在蒙特卡罗数值模拟中简单实现。最后，讨论了该方法在负离子源的一些感兴趣的案例中的应用。