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In this paper, a vacuum system is employed to compare the emission stabilities of the same ZnO cathode in a sealed field emission (FE) device and under ultrahigh vacuum (UHV) conditions. It is observed that the emission current is more stable under the UHV level than in the device. When all conditions except the ambient gases are kept unchanged, the emission current degradation is mainly caused by the residual gases in the sealed device. The quadrupole mass spectrometer (QMS) equipped on the vacuum system is used to investigate the residual gas components. Based on the obtained QMS data, the following conclusions can be drawn: the residual gases in ZnO-FE devices are H2, CH4, CO, Ar, and CO2. These residual gases can change the work function at the surface through adsorption or ion bombardment, thereby degrading the emission current of the cathode. 相似文献
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分数傅立叶变换的进展与展望 总被引:3,自引:1,他引:2
在综合国内外有关文献的基础上,评述分数傅立叶变换在信息光学中的新进展。概述分数傅立叶变换的发展过程,并对其研究现状进行了简略总结,同时对其未来的发展作出展望。 相似文献
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