Gas-aggregation source (GAS) was used to prepare Cu nanoparticles. By changing the diameter of the exit orifice of the aggregation chamber, we were able to isolate and investigate the effect of the flow rate of the working gas at a constant pressure inside the aggregation chamber. We show that the conventional approach of changing pressure by adjusting the flow rate (at a constant orifice diameter) does not significantly influence the nanoparticle size. However, when the pressure is held constant, changing the flow rate has a notable effect. Based on a theoretical study, we suggest that the determining parameter which needs to be considered is the pressure to flow rate ratio. This ratio determines the residence time of the nanoparticles inside the aggregation chamber (and therefore the time available for them to grow) and is constant for a constant orifice diameter. Decreasing the orifice diameter, however, increases the pressure to flow rate ratio, which gives the nanoparticles longer time inside the aggregation chamber and allows them to grow larger. Apart from their size, the orifice diameter also influences the mass flux and its angular distribution.

气体聚集源（GAS）用于制备Cu纳米粒子。通过更改聚集室出口孔的直径，我们能够隔离和研究聚集室内部恒定压力下工作气体流速的影响。我们表明，通过调节流速（在恒定的孔直径下）来改变压力的常规方法不会显着影响纳米颗粒的尺寸。然而，当压力保持恒定时，改变流量具有显着的效果。根据理论研究，我们建议需要考虑的确定参数是压力与流量之比。该比率决定了纳米颗粒在聚集室内的停留时间（因此决定了它们可用于生长的时间），并且对于恒定的孔直径而言是恒定的。但是，减小孔的直径会增加压力与流速的比率，从而使纳米粒子在聚集室内的时间更长，并使它们变得更大。除其尺寸外，孔口直径还会影响质量通量及其角度分布。