Dependence of cluster size on throat diameter of conical nozzle in supersonic gas jet

In the field of intense laser interaction with gas cluster, the cluster size is an important parameter. However, there will exist deviation if the cluster size at a high gas backing pressure is estimated by a usual method (<i>i.e.</i>, Hagena scaling law). This work aims to investigate whether the deviation is relative to the effect of throat diameter of conical nozzle on average cluster size. To re-investigate the effect of throat diameter, three conical nozzles with throat diameters of 0.3 mm, 0.5 mm and 0.7 mm are used to produce the argon gas jet. Rayleigh scattering method is used to measure the average cluster size. The gas backing pressures are changed from 10 up to 80 bar. By exploring the dependence of cluster size on the throat diameter of nozzle, it is found that the effect of the throat diameter on cluster size is in roughly agreement with that expected by Hagena scaling law, even at high gas backing pressures. That is to say, the cluster size deviation in the scaling law could result from other factors. The result is helpful for a further understanding of the scaling law and the intense laser interaction with clusters.