As the cathode with the highest electron emission capability in the thermionic cathode,the scandate cathode has attracted more and more attention in recent years,especially the scandia doped tungsten matrix scandate c...As the cathode with the highest electron emission capability in the thermionic cathode,the scandate cathode has attracted more and more attention in recent years,especially the scandia doped tungsten matrix scandate cathode.Experimental studies show that scandia doped tungsten matrix scandate cathodes with submicron microstructures exhibit excellent emission capacity,and the pulse emission current density in the space-charge region can be over 35 A cm^(−2) at 850°Cb.In the direct current(DC)condition with temperature compensation,the emission current density could reach 25 A cm^(−2) at 850°Cb.The device lifetime is over 3700 h after operating at 950°C_(b) with the DC loading of 40 A cm^(−2).The emission mechanism of the scandate cathode including the effect of the surface structure and composition on the work function of the cathode are systematically reviewed.展开更多
By using correlation-detection technique and improving structure of the test tube,the background noise of thermionic-electrons and space charge effect are restrained.The sec-ondary emission coefficient δ of thermioni...By using correlation-detection technique and improving structure of the test tube,the background noise of thermionic-electrons and space charge effect are restrained.The sec-ondary emission coefficient δ of thermionic cathode at high temperature has been studied.Theδ of impregnated scandate cathodes increases exponentially with increasing temperature at lowenergy and current of the bombardment electrons;at high energy or current of the bombardmentelectrons the temperature has little effect on δ.The research shows that an enhanced thermionicemission occurred when the cathode works at high temperature and under electron bombardment.These phenomena are discussed in terms of “internal field model”.展开更多
基金the National Key Research and Development Program of China(Grant 2017YFB0305600)National Science Foundation of China(Grant 51534009,51621003)Beijing Municipal High Level Innovative Team Building Program(Grant IDHT 20170502).
文摘As the cathode with the highest electron emission capability in the thermionic cathode,the scandate cathode has attracted more and more attention in recent years,especially the scandia doped tungsten matrix scandate cathode.Experimental studies show that scandia doped tungsten matrix scandate cathodes with submicron microstructures exhibit excellent emission capacity,and the pulse emission current density in the space-charge region can be over 35 A cm^(−2) at 850°Cb.In the direct current(DC)condition with temperature compensation,the emission current density could reach 25 A cm^(−2) at 850°Cb.The device lifetime is over 3700 h after operating at 950°C_(b) with the DC loading of 40 A cm^(−2).The emission mechanism of the scandate cathode including the effect of the surface structure and composition on the work function of the cathode are systematically reviewed.
文摘By using correlation-detection technique and improving structure of the test tube,the background noise of thermionic-electrons and space charge effect are restrained.The sec-ondary emission coefficient δ of thermionic cathode at high temperature has been studied.Theδ of impregnated scandate cathodes increases exponentially with increasing temperature at lowenergy and current of the bombardment electrons;at high energy or current of the bombardmentelectrons the temperature has little effect on δ.The research shows that an enhanced thermionicemission occurred when the cathode works at high temperature and under electron bombardment.These phenomena are discussed in terms of “internal field model”.
