The magnetic mirror field caused by a pair of mild steel circular in 15mm diameter, 2 mm thickness placed outside the discharge chamber can increase the atom ion ratio of nitrogen from 66% to 81 %, and the heating fil...The magnetic mirror field caused by a pair of mild steel circular in 15mm diameter, 2 mm thickness placed outside the discharge chamber can increase the atom ion ratio of nitrogen from 66% to 81 %, and the heating filament current can be decreased from 130 A down to 100 A for a new filament of 2 mm in diameter. The Mo shield cylinders in 14mm diameter put behind the reflect cathode surrounding the BN insulator prevent the metallization of BN insulators, and result in increasing the stability of arc discharge till to the end of filament working life. Because it restricts the deposition of the sputtered W and Mo atoms on the BN insulator, and maintains a high resistance of 70 Mad between the anode and cathode. The combination of cathode shield cylinder and forming magnetic mirror field improves the running property, life of the Freeman source being about 40 h.展开更多
To acquire a rational minimum cut-off time and the precision of lifetime prediction with respect to cut-off time for the accelerated aging test of LED lamps, fifth-order moving average error estimation is adopted in t...To acquire a rational minimum cut-off time and the precision of lifetime prediction with respect to cut-off time for the accelerated aging test of LED lamps, fifth-order moving average error estimation is adopted in this paper. Eighteen LED lamps from the same batch are selected for two accelerated aging tests, with 10 samples at 80 ℃ and eight samples at 85 ℃. First, the accelerated lifetime of each lamp is acquired by exponential fitting of the lumen maintenances of the lamp for a certain cut-offtime With the acquired lifetimes of all lamps, the two-parameter Weibull distribution of the failure probability is obtained, and the medium lifetime is calculated. Then, the precision of the medium lifetime prediction for different cut-off times is obtained by moving average error estimation. It is shown that there exists a minimum cut-off time for the accelerated aging test, which can be determined by the variation of the moving average error versus the cut-offtime. When the cut-off time is less than this value, the lifetime estimation is irrational. For a given cut-off time, the precision of lifetime prediction can be computed by average error evaluation, and the error of lifetime estimation decreases gradually as the cut-off time- increases. The minimum cut-off time and medium lifetime of LED lamps are both sensitive to thermal stress. The minimum cut-off time is 1104 h with the lifetime esti- mation error of 1.15% for the test at 80 ~C, and 936 h with the lifetime estimation error of 1.24% for the test at 85 ℃. With the lifetime estimation error of about 0.46%, the median lifetimes are 7310 h and 4598 h for the tests at 80 ℃ and 85℃, respectively.展开更多
文摘The magnetic mirror field caused by a pair of mild steel circular in 15mm diameter, 2 mm thickness placed outside the discharge chamber can increase the atom ion ratio of nitrogen from 66% to 81 %, and the heating filament current can be decreased from 130 A down to 100 A for a new filament of 2 mm in diameter. The Mo shield cylinders in 14mm diameter put behind the reflect cathode surrounding the BN insulator prevent the metallization of BN insulators, and result in increasing the stability of arc discharge till to the end of filament working life. Because it restricts the deposition of the sputtered W and Mo atoms on the BN insulator, and maintains a high resistance of 70 Mad between the anode and cathode. The combination of cathode shield cylinder and forming magnetic mirror field improves the running property, life of the Freeman source being about 40 h.
基金supported by the National High-Tech R&D Program(863)of China(Nos.2015AA03A101 and 2013AA03A116)the Cui Can Project of Chinese Academy of Sciences(No.KZCC-EW-102)
文摘To acquire a rational minimum cut-off time and the precision of lifetime prediction with respect to cut-off time for the accelerated aging test of LED lamps, fifth-order moving average error estimation is adopted in this paper. Eighteen LED lamps from the same batch are selected for two accelerated aging tests, with 10 samples at 80 ℃ and eight samples at 85 ℃. First, the accelerated lifetime of each lamp is acquired by exponential fitting of the lumen maintenances of the lamp for a certain cut-offtime With the acquired lifetimes of all lamps, the two-parameter Weibull distribution of the failure probability is obtained, and the medium lifetime is calculated. Then, the precision of the medium lifetime prediction for different cut-off times is obtained by moving average error estimation. It is shown that there exists a minimum cut-off time for the accelerated aging test, which can be determined by the variation of the moving average error versus the cut-offtime. When the cut-off time is less than this value, the lifetime estimation is irrational. For a given cut-off time, the precision of lifetime prediction can be computed by average error evaluation, and the error of lifetime estimation decreases gradually as the cut-off time- increases. The minimum cut-off time and medium lifetime of LED lamps are both sensitive to thermal stress. The minimum cut-off time is 1104 h with the lifetime esti- mation error of 1.15% for the test at 80 ~C, and 936 h with the lifetime estimation error of 1.24% for the test at 85 ℃. With the lifetime estimation error of about 0.46%, the median lifetimes are 7310 h and 4598 h for the tests at 80 ℃ and 85℃, respectively.
