Nonthermal plasma flow tube reactors are industrially scalable systems for the production of nanocrystal (NC) based materials and coatings. One key advantage of nonthermal plasma synthesis is the ability to both synthesize NCs and deposit films in a single reactor, as at the reactor outlet, NCs can be inertially deposited onto a target substrate. The size and morphology of deposited particles can substantially influence the film structure and function. Though NCs are typically near-spherical and monodispersed as-produced in plasma synthesis reactors, NC charge and growth dynamics can be altered substantially when NCs are sampled out of the plasma and through the spatial afterglow region, affecting deposition. Experiments have demonstrated changes of NC size and charge in the spatial afterglow; however, these dynamics remain unexplored and unexplained via theory and simulation. To address this, we developed a constant number Monte Carlo (CNMC) simulation model to examine the mechanisms of NC decharging and growth in the spatial afterglow of plasma flow tube reactors. Collisions between NC and plasma species, diffusive deposition, and electron desorption from NCs are incorporated in the CNMC simulation. The simulation results are specifically compared with previous experiments on Si NCs synthesized from a low pressure Ar-SiH₄ nonthermal plasma reactor. The experiment-model comparison shows that CNMC models can be implemented which accurately model NC size distribution evolution in a spatial afterglow. Simultaneously, results show that improved collision models, energetic species diffusion models, and electron desorption models will be necessary to accurately depict NC dynamics in spatial afterglows.

非热等离子体流管反应器是工业上可扩展的系统，用于生产基于纳米晶体（NC）的材料和涂层。非热等离子体合成的一个关键优势是能够在单个反应器中合成NC和沉积膜的能力，因为在反应器出口处，NC可以惯性地沉积在目标衬底上。沉积颗粒的大小和形态会大大影响薄膜的结构和功能。尽管NCs通常是在等离子体合成反应器中产生的接近球形的单分散体，但是当从血浆中以及通过空间余辉区域采样NCs时，NC电荷和生长动力学会发生很大变化，从而影响沉积。实验证明了空间余辉中NC尺寸和电荷的变化。然而，这些动力学仍然无法通过理论和模拟来探索和解释。为了解决这个问题，我们开发了一个常数蒙特卡罗（CNMC）模拟模型，以检查等离子流管反应器的空间余辉中NC放电和增长的机理。NC和等离子体物质之间的碰撞，扩散沉积以及NC中的电子脱附都被包含在CNMC模拟中。将模拟结果与以前的由低压Ar-SiH合成的Si NC的实验进行了比较 CNNC中的电子解吸和NCs中的电子解吸被纳入CNMC模拟中。将模拟结果与以前的由低压Ar-SiH合成的Si NC的实验进行了比较 CNNC中的电子解吸和NCs中的电子脱附都包含在CNMC模拟中。将模拟结果与以前的由低压Ar-SiH合成的Si NC的实验进行了比较_4个非热等离子体反应器。实验模型的比较表明，可以实现CNMC模型，该模型可以精确地模拟空间余辉中NC尺寸分布的演变。同时，结果表明，改进的碰撞模型，高能物种扩散模型和电子解吸模型对于准确描述空间余辉中的NC动力学将是必要的。