Solar wind stream interaction regions (SIRs) are often characterized by energetic ion enhancements. The mechanisms accelerating these particles, as well as the locations where the acceleration occurs, remain debated. Here, we report the findings of a simulation of a SIR event observed by Parker Solar Probe at ∼0.56 au and the Solar Terrestrial Relations Observatory-Ahead at ∼0.95 au in 2019 September when both spacecraft were approximately radially aligned with the Sun. The simulation reproduces the solar wind configuration and the energetic particle enhancements observed by both spacecraft. Our results show that the energetic particles are produced at the compression waves associated with the SIR and that the suprathermal tail of the solar wind is a good candidate to provide the seed population for particle acceleration. The simulation confirms that the acceleration process does not require shock waves and can already commence within Earth’s orbit, with an energy dependence on the precise location where particles are accelerated. The three-dimensional configuration of the solar wind streams strongly modulates the energetic particle distributions, illustrating the necessity of advanced models to understand these particle events.

太阳风相互作用区域（SIR）通常以高能离子增强为特征。加速这些粒子的机制以及加速发生的位置仍在争论中。在这里，我们报告了2019年9月帕克太阳探测器在〜0.56 au处观测到的SIR事件的模拟结果，以及2019年9月在〜0.95 au处前方的太阳陆地关系观测站观测到的SIR事件的模拟结果，当时两艘航天器均大致与太阳径向对准。该模拟再现了两个航天器观测到的太阳风配置和高能粒子增强。我们的结果表明，高能粒子是在与SIR相关的压缩波处产生的，并且太阳风的超热尾部是为粒子加速提供种子种群的良好候选者。该模拟证实，加速过程不需要冲击波，并且已经可以在地球轨道内开始，其能量依赖于粒子被加速的精确位置。太阳风的三维结构强烈地调节了高能粒子的分布，这说明了高级模型了解这些粒子事件的必要性。