In present work, we report an experimental setup that has been developed to characterize highly under-expanded helium and nitrogen jets confined in a vacuum chamber. The evolution of Zone of Silence (ZOS) is studied and found that experimentally measured ZOS for helium and nitrogen jets are in agreement with empirical relation and mathematical model. The velocity of the jet inside ZOS is measured using a developed time of fight (TOF) probe without using a skimmer. We are able to measures the velocity of the gas jet itself compared to a skimmer based method which measures the velocity of gas that is subjected to further expansion after the skimmer. Moreover, this method is free from skimmer interference and calibration involved with it. We observe that the measured velocity for helium is smaller than the terminal velocity. This can be attributed to losses which can occur due to nozzle geometry. Simulations are carried out using available DS2V code. Experimentally observed velocities of jets inside ZOS are compared with simulated values and are found to be in agreement within experimental uncertainties.

在目前的工作中，我们报告了一种实验装置，该装置已开发用于表征限制在真空室中的高度膨胀不足的氦气和氮气射流。研究了寂静区（ZOS）的演化，发现实验测量的氦气和氮气射流的ZOS与经验关系和数学模型一致。ZOS 内的射流速度是使用开发的战斗时间 (TOF) 探头测量的，而不使用撇油器。与基于撇渣器的方法相比，我们能够测量气体射流本身的速度，后者测量在撇渣器后进一步膨胀的气体速度。此外，该方法不受撇渣器干扰和与之相关的校准。我们观察到氦的测量速度小于终端速度。这可以归因于可能由于喷嘴几何形状而发生的损失。使用可用的 DS2V 代码进行模拟。实验观察到的 ZOS 内射流速度与模拟值进行比较，发现在实验不确定性范围内是一致的。