In this paper, design and construction of a modified cold molybdenum cathode Penning ion source was described. It consists of copper cylindrical anode with two cone ends and two movable cold molybdenum cathodes. The t...In this paper, design and construction of a modified cold molybdenum cathode Penning ion source was described. It consists of copper cylindrical anode with two cone ends and two movable cold molybdenum cathodes. The two cathodes were placed symmetrically at two ends of the anode. The modifications were decrease the length of the cylindrical anode to 4 cm instead of 6 cm, transform the copper emission electrode shape from plate of 40 mm length, 25 mm width and 2 mm thickness to disc of 20 mm diameter and 2 mm thickness and transform the inner uncovered area of the emission electrode from slit of 30 mm length and 10 mm width to disc of 5 mm diameter. The copper emission electrode was placed in the middle of the cylindrical anode and has aperture in the center of different diameters. Faraday cup was placed at different distances from the emission electrode aperture. The electrical discharge and the output ion beam characteristics of the modified ion source were measured at different pressures using argon gas. It was found that the optimum operating conditions of the modified ion source are; anode-cathode distance equal to 6 mm, emission electrode aperture diameter equal to 2.5 mm and emission electrode aperture, Faraday cup distance equals 3 cm. The effect of axial samarium cobalt permanent magnet of intensity equal to 300 Gauss on the discharge characteristics of the ion source was determined.展开更多
Two types of secondary emitter materials, the rare earth oxides(RE_2O_3) doped Mo cermet cathodes and the Y_2O_3-W matrix pressed cathode, are introduced in this paper. According to the calculation results, Y_2O_3 exh...Two types of secondary emitter materials, the rare earth oxides(RE_2O_3) doped Mo cermet cathodes and the Y_2O_3-W matrix pressed cathode, are introduced in this paper. According to the calculation results, Y_2O_3 exhibits the best secondary emission property among Y_2O_3,La_2O_3,CeO_2 and Lu_2O_3. The rare earth oxides co-doped Mo cathodes in which Y_2O_3 is the main active substance exhibit better secondary emission property than single RE_2O_3 doped Mo cathode. The results obtained by the Monte-Carlo calculation method show that the secondary electron emission property is strongly related to the grain size of the cathode. The decreasing of the grain size reduces the positive charge effect of the rare earth oxide due to the electrons supplement from the metal to the rare earth oxide, whereby the secondary electrons are easier to escape into the vacuum. Y_2O_3 is introduced into Ba-W cathode to fabricate a pressed Y_2O_3-W matrix dispenser cathode. The result indicates that the secondary emission yield of the Ba-W cathode increases from 2.13 to 3.51 by adding Y_2O_3, and the thermionic emission current density(J_0) could reach 4.18 A/cm^2 at 1050 ℃b.展开更多
Molybdenum trioxide （MOO3） as a cathode buffer layer is inserted between LiF and A1 to improve the efficiency of white organic light-emitting diodes （OLEDs） in this paper..By changing the MoO3 thickness, a higher ...Molybdenum trioxide （MOO3） as a cathode buffer layer is inserted between LiF and A1 to improve the efficiency of white organic light-emitting diodes （OLEDs） in this paper..By changing the MoO3 thickness, a higher current efficiency of 5.79 cd/A is obtained at a current density of 160 mA/cm2 for the device with a 0.8 nm-thick MoO3 layer as the cathode buffer layer, which is approximately two times greater than that of the device without MoO3. The mechanism for improving the device efficiency is discussed. Moreover, at a voltage of 13 V, the device with a 0.8 nm-thick MoO3 layer achieves a higher luminance of 22370 cd/m2, and the Commission Internationale de I＇Eclairage （CIE） color coordinate of the device with 1 nm-thick MoO3 layer is （0.33, 0：34）, which shows the best color purity. Simple electron-only devices are tested to confirm the impact of the MoO3 layer on the carrier injection.展开更多
文摘In this paper, design and construction of a modified cold molybdenum cathode Penning ion source was described. It consists of copper cylindrical anode with two cone ends and two movable cold molybdenum cathodes. The two cathodes were placed symmetrically at two ends of the anode. The modifications were decrease the length of the cylindrical anode to 4 cm instead of 6 cm, transform the copper emission electrode shape from plate of 40 mm length, 25 mm width and 2 mm thickness to disc of 20 mm diameter and 2 mm thickness and transform the inner uncovered area of the emission electrode from slit of 30 mm length and 10 mm width to disc of 5 mm diameter. The copper emission electrode was placed in the middle of the cylindrical anode and has aperture in the center of different diameters. Faraday cup was placed at different distances from the emission electrode aperture. The electrical discharge and the output ion beam characteristics of the modified ion source were measured at different pressures using argon gas. It was found that the optimum operating conditions of the modified ion source are; anode-cathode distance equal to 6 mm, emission electrode aperture diameter equal to 2.5 mm and emission electrode aperture, Faraday cup distance equals 3 cm. The effect of axial samarium cobalt permanent magnet of intensity equal to 300 Gauss on the discharge characteristics of the ion source was determined.
基金the National Natural Science Foundation of China(GrantNos 51471006,51534009,52621003,51225402)
文摘Two types of secondary emitter materials, the rare earth oxides(RE_2O_3) doped Mo cermet cathodes and the Y_2O_3-W matrix pressed cathode, are introduced in this paper. According to the calculation results, Y_2O_3 exhibits the best secondary emission property among Y_2O_3,La_2O_3,CeO_2 and Lu_2O_3. The rare earth oxides co-doped Mo cathodes in which Y_2O_3 is the main active substance exhibit better secondary emission property than single RE_2O_3 doped Mo cathode. The results obtained by the Monte-Carlo calculation method show that the secondary electron emission property is strongly related to the grain size of the cathode. The decreasing of the grain size reduces the positive charge effect of the rare earth oxide due to the electrons supplement from the metal to the rare earth oxide, whereby the secondary electrons are easier to escape into the vacuum. Y_2O_3 is introduced into Ba-W cathode to fabricate a pressed Y_2O_3-W matrix dispenser cathode. The result indicates that the secondary emission yield of the Ba-W cathode increases from 2.13 to 3.51 by adding Y_2O_3, and the thermionic emission current density(J_0) could reach 4.18 A/cm^2 at 1050 ℃b.
基金supported by the National Natural Science Foundation of China(No.61076066)the Doctor Foundation of Shaanxi University of Scienceand Technology(No.BJ09-07)
文摘Molybdenum trioxide （MOO3） as a cathode buffer layer is inserted between LiF and A1 to improve the efficiency of white organic light-emitting diodes （OLEDs） in this paper..By changing the MoO3 thickness, a higher current efficiency of 5.79 cd/A is obtained at a current density of 160 mA/cm2 for the device with a 0.8 nm-thick MoO3 layer as the cathode buffer layer, which is approximately two times greater than that of the device without MoO3. The mechanism for improving the device efficiency is discussed. Moreover, at a voltage of 13 V, the device with a 0.8 nm-thick MoO3 layer achieves a higher luminance of 22370 cd/m2, and the Commission Internationale de I＇Eclairage （CIE） color coordinate of the device with 1 nm-thick MoO3 layer is （0.33, 0：34）, which shows the best color purity. Simple electron-only devices are tested to confirm the impact of the MoO3 layer on the carrier injection.
