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The hot gas is widely distributed in the universe and is closely related to accretion and various feedback processes of galaxies. The study of the hot gas not only is the key to solving the missing baryon problem but also is very important to understand the formation and evolution of the galaxies. To detect the hot gas, the Hot Universe Baryon Surveyor (HUBS) project plans to launch an X-ray science satellite around 2030. The satellite will be equipped with an X-ray telescope with a large field of view, large effective area, and high energy resolution. In preparation, it is necessary to quantify the scientific capabilities of HUBS in studying the hot gas and provide the basis for the design optimization of the instrument and future scientific research work. To this end, we created mock HUBS observations with the state-of-the-art cosmological simulation, IllustrisTNG. From the observations, we made mock X-ray images and spectra, analyzed them to derive the properties of the emitting gas in each case, and compared the results with the input parameters from the simulation. The results show that HUBS is well suited for studying hot CGM at low redshifts. The redshift range is significantly extended for measuring IGrM and ICM. In addition, we have developed a number of primary studies of the star-forming galaxies and the filament structures in the line-of-sight. Related reference papers and ADS links:https://ui.adsabs.harvard.edu/abs/2022ExA....53.1053Z/abstract, This talk is one of the Xtalk+ series.

Because of the excellent field emission performances, the carbon nanotube array has already been used as the cold electron source in the field emission display, the vacuum microwave tube, and the electron microscopy, etc. It is necessary to estimate the emission performance of the carbon nanotube array in the design of these devices. The emission current density of a single carbon nanotube can be estimated with the Fowler–Nordheim formula approximately. Thus, the emission performance of the whole array is obtained by the sum of the current emitted from all carbon nanotubes in the array. However, this calculation is very complex and time consuming due to the large number of carbon nanotubes in the array. This paper proposes a simple model to predict the emission performance of the whole CNT array. The total emission current can be deduced easily with this model if we know the geometrical parameters of the CNT array. A few experiments have been performed to verify this model. With this model, the influences of geometric dimensions of the CNT array on the emission performance are also discussed.

In this paper, some optimum field emission displays (FEDs) elements are proposed using numerical analyses to improve the emission performances, to decrease the driving voltage and to improve other driving performances of these devices with different structures like diode structure, normal-gate structure, and under-gate structure.