The size and size distribution of nanomaterials are important factors for understanding their characteristics. A scanning electron microscopy (SEM) provides an easily accessible method to characterize nanostructures. We have developed a standard operating protocol (SOP) for the calibration of SEM by using CRMs (certified reference materials) of 1 dimensional (1D) gratings with 80 and 180 nm spacing, respectively, which have been certified by using a metrological AFM. To get consistent analysis results using a fast Fourier transform (FFT) method, the numbers of lateral and longitudinal pixels in the SEM images were determined for line profiling. We could also observed that the pitch values of 1D grating CRM could be obtained as the reference ones within the uncertainty under the following imaging conditions; the exposure time of the sample to the electron beam for an image scanning should be shorter than 120 s and the working distance from 5 to 8.9 mm can be used.
From the geometric parameter study, an optimal ejector design procedure of pressure recovery system for chemical lasers was acquired. For given primary flow reservoir conditions, an up-scaled ejector was designed and manufactured. In the performance test, secondary mass flow rate of 200g/s air was entrained satisfying the design secondary pressure, 40 ~ 50torr. Performance validation of a supersonic ejector system along with an investigation of effects of supersonic diffuser was conducted. Placement of the diffuser at the secondary inlet further reduced diffuser upstream pressure to 7torr. Lastly, the duplicate of apparatus (air 100 g/s secondary mass flow rate each) was built and connected in parallel to assess proportionality behavior on a system to handle larger mass flow rate. Test and comparison of the parallel unit demonstrated the secondary mass flow rate was proportional to the number of individual units that were brought together maintaining the lasing pressure.
Axi-symmetric annular type ejector has been developed as a pressure recovery system for HF/DF chemical laser. Ejector was tested using air as operating gases and low-pressure entrained flow was obtained. In this paper, we changed motive gas since operating gases for chemical laser system are products of chemical reaction. By selection of motive gas, physical properties of operating gas changes, therefore the performance of ejector is different for each motive gas, i.e., specific heat at constant pressure (CP) and average molecular weight (MW) on the effectiveness of ejection. The research was carried out by both numerical analysis using commercial CFD code, FLUENT and experiments.