Flat-panel X-ray sources(FPXSs)have many advantages in terms of compactness and low-dose imaging,enhancing their capability for novel X-ray applications.Experimental analysis of the X-ray characteristics and optimizin...Flat-panel X-ray sources(FPXSs)have many advantages in terms of compactness and low-dose imaging,enhancing their capability for novel X-ray applications.Experimental analysis of the X-ray characteristics and optimizing the anode panel of an FPXS are time-consuming,expensive,and sometimes impractical.In this study,a FPXS was prepared using a ZnO nanowire cold cathode and a molybdenum film anode target.Monte Carlo(MC)simulations were utilized to optimize the anode panel and obtain the average fluence,average energy,and spatial distribution of the X-rays for the ZnO nanowire FPXS.The accuracy of the MC simulations was verified by comparing the measured and simulated energy spectra.Optimization of the anode target considers the material,thickness,and morphology,whereas optimization of the substrate focuses on the material and thickness.The results show that the difference between the positions of the K-shell peaks in the measured and simulated energy spectra is within 0.26 keV.At the acceleration voltages of 30 kV,60 kV,and 90 kV,the optimal thicknesses of the tungsten array anode were 0.65μm,2.45μm,and 5μm,respectively,while the molybdenum array anode has the optimal thicknesses of 1.45μm,5.25μm,and 24μm,respectively.The microsemi-ellipsoidal anode with a recessed design showed a 5%increase in the transmitted X-ray fluence compared with the film target.The sapphire substrate with a thickness of 0.78 mm exhibits a mechanical strength comparable to that of a glass substrate with a thickness of 3 mm,implying that the former can increase the average X-ray fluence by reducing the filtration of X-rays.The findings of this study provide valuable guidance for the fabrication and optimization of the ZnO nanowire FPXS.展开更多
In order to develop miniaturized and integrated electron vacuum devices, the electron beam modulation in a field- emission （FE） electron gun based on carbon nanotubes is researched. By feeding a high-frequency field...In order to develop miniaturized and integrated electron vacuum devices, the electron beam modulation in a field- emission （FE） electron gun based on carbon nanotubes is researched. By feeding a high-frequency field between the cathode and the anode, the steady FE electron beam can be modulated in the electron gun. The optimal structure of the electron gun is discovered using 3D electromagnetism simulation software, and the FE electron gun is simulated by PIC simulation software. The results show that a broadband （74-114 GHz） modulation can be achieved by the electron gun with a rhombus channel, and the modulation amplitude of the beam current increases with the increases in the input power and the electrostatic field.展开更多
With high effective screen-printing technique, a new triode field emission display (FED)with enhanced petaling cold cathode was fabricated. For enhancing the field emission performance,a series of improved measures wa...With high effective screen-printing technique, a new triode field emission display (FED)with enhanced petaling cold cathode was fabricated. For enhancing the field emission performance,a series of improved measures was adopted in the fabrication course. Seen from the fabrication structure of enhanced petaling cold cathode,the bar conducting electrode and the petaling bottom electrode were fabricated with the sintered silver slurry on cathode glass faceplate. The luminescence image with green phosphor was displayed for the sealed enhanced petaling cold cathode FED. The measured results showed that the enhanced petaling cold cathode had good field emission performance. The enhanced petaling cold cathode FED possessed low turn-on electric-field of 1. 95 V /μm,large emission current of 1 389. 6 μA,and high luminance brightness of 1 520 cd /m2 .展开更多
The field emission characteristics of the AlN thin films with micro-scaled cold cathode structures are tested in the high vacuum system. The aluminum nitride （A1N） thin films with a thickness of about 100 nm are pre...The field emission characteristics of the AlN thin films with micro-scaled cold cathode structures are tested in the high vacuum system. The aluminum nitride （A1N） thin films with a thickness of about 100 nm are prepared on the n-type 6H-SiC （0001） substrate at 1100℃ by metal organic chemical vapor deposition （MOCVD） under low pressure. The I-V curves and surface micro-images of undoped and Si-doped AlN films are investigated. From the I-V and Fowler-Nordheim plots, it can be seen that the Si-doped AlN shows better field emission characteristics compared with the undoped AlN sample. The obtained turn-on field is 6.7 V/μm and the maximum emission current density is 154 mA/cm2 at 69.3 V for the Si- doped AlN film cathode after proper surface treatment. It is proposed that the relatively low electric resistivity of Si-doped AlN films is significant for electron migration to the surface region, and their rougher surface morphology is beneficial to a higher local electric field enhancement for the field emission.展开更多
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
This paper mainly investigates plasma characterization on carbon fiber cathodes with and without cesium iodide （CsI） coating powered by a - 300 ns, - 200 kV accelerating pulse. It was found that the CsI layers can n...This paper mainly investigates plasma characterization on carbon fiber cathodes with and without cesium iodide （CsI） coating powered by a - 300 ns, - 200 kV accelerating pulse. It was found that the CsI layers can not only improve the diode voltage, but also maintain a stable perveance. This indicates a slowly changed diode gap or a low cathode plasma expansion velocity. By spectroscopic diagnostics, in the vicinity of the cathode surface the average plasma density and temperature were found to be -3×10^14 cm^-3 and - 5 eV, respectively, for an electron current density of - 40 A/cm^2. Furthermore, there exists a multicomponent plasma expansion toward the anode. The plasma expansion velocity, corresponding to the carbon and hydrogen ions, is estimated to be - 1.5 cm/μs. Most notably, Cs spectroscopic line was obtained only at the distance - 0.5 mm from the cathode surface. Carbon and hydrogen ions are obtained up to the distance of 2.5 mm from the cathode surface. Cs ions almost remain at the vicinity of the cathode surface. These results show that the addition of CsI enables a slow cathode plasma expansion toward the anode, providing a positive prospect for developing long-pulse electron beam sources.展开更多
The remaining challenges, confronting high-power microwave （HPM） sources and pulsed power generators, stim- ulate the developments of robust relativistic electron beam sources. This paper presents a carbon fibre cat...The remaining challenges, confronting high-power microwave （HPM） sources and pulsed power generators, stim- ulate the developments of robust relativistic electron beam sources. This paper presents a carbon fibre cathode which is tested in a single pulsed power generator. The distribution and the development of cathode plasma are observed by time-and-space resolved diagnostics, and the uniformity of electron beam density is checked by taking x-ray images. A quasistationary behaviour of cathode plasma expansion is observed. It is found that the uniformity of the extracted electron beam is satisfactory in spite of individual plasma jets on the cathode surface. These results show that carbon fibre cathodes can provide a positive prospect for developing a high-quality electron beam.展开更多
The Ba x-0.05MgAl 10O 16+x∶Eu 2+ 0.05 (0.88≤x ≤1.02) phosphors with different Ba 2+ content and the Ba 0.85MgAl 10O 16.94∶Eu 2+ 0.09 phosphors with different fluxes (BaF 2, MgF 2, AlF ...The Ba x-0.05MgAl 10O 16+x∶Eu 2+ 0.05 (0.88≤x ≤1.02) phosphors with different Ba 2+ content and the Ba 0.85MgAl 10O 16.94∶Eu 2+ 0.09 phosphors with different fluxes (BaF 2, MgF 2, AlF 3, BaCl 2, MgCl 2, AlCl 3, H 3BO 3) were prepared by high temperature solid-state reaction method and their luminescence characteristics were studied under 254 nm excitation and vacuum ultraviolet (VUV) excitation. With the increase of the Ba 2+ content, there is an increase in the emission intensity, and when x=0.94, it reaches a maximum. Then, as the Ba 2+ content increases, the emission intensity slowly falls. The fluorides have better flux-effects than chlorides and H 3BO 3. The possible mechanism in the process of particle growth was discussed when fluorides were used as fluxes. The effect of the activator concentration on this system was also investigated. The quenching concentration is 0.13 mol in per mole host.展开更多
Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adeq...Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance（ECR） system for the ‘whistler/chorus＇ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén＇ wave study. The parameters of ‘whistler/chorus＇ waves and ‘Alfvén＇ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt＇ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.展开更多
High calcination temperature is an important factor in the preparation process of CeMgAl 11O 19∶Tb 3+. To decrease the temperature, different fluxes (H 3BO 3, MgF 2 and AlF 3) were tested in order to compa...High calcination temperature is an important factor in the preparation process of CeMgAl 11O 19∶Tb 3+. To decrease the temperature, different fluxes (H 3BO 3, MgF 2 and AlF 3) were tested in order to compare their influence on the luminescence property and particle size distribution of CeMgAl 11O 19∶Tb 3+. The result shows that when the content of MgF 2 is 0.1 mol/mol, the intensity of luminescence can attain a maximum. Furthermore, MgF 2 can improve the particle size quality of the phosphor. So MgF 2 can take the place of the conventional flux H 3BO 3 to prepare high quality CeMgAl 11O 19∶Tb 3+ phosphor. In addition, the relation between phosphor property and content of AlF 3 was also studied. The crystal structure of the phosphor was analyzed by XRD method. The phase composition analysis shows that the reason of decrease of the brightness of CeMgAl 11O 19∶Tb 3+ phosphor is the emergence of TbAlO 3 and α-Al 2O 3 during the preparation process.展开更多
PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circui...PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circuit is used to conduct simulations, leading to a precise modeling. A library is configured through modeling and its accuracy is verified through simulations for widely used and representative lamps such as CCFL, fluorescent lamps, HID lamps, and electrodeless fluorescent lamps. On the basis of experiments, a lamp simulation is also performed using PSPICE, which allows us to take advantage of the lamp library easily. Also, PSPICE model driven by an electric equivalent circuit of a piezoelectric transformer is presented. In order to confirm this model to be effective, an independent model of CCFL driving circuit is used to conduct simulations, leading to a precise modeling. In addition, a new type of electronic ballast is proposed, which allows 35 W-class(T5-class) fluorescent lamp to work. This system is built by a rectifier which has improved power factor and half-bridge series resonant inverter. Also, with size of 27.5 mm high, 27.5 mm wide and 2.5 mm thick, the produced piezoelectric transformer has a high step-up ratio, through which it is possible for the electric ballast circuit to be lighter, smaller and more efficient. After the produced ballast is used to drive the fluorescent lamp for 25 min, it yields 0.95 in power factor correction, 86% in efficiency, 35.07 W in output voltage and 20.5 °C in temperature increase while meeting the characteristics of the 35 W-class fluorescent lamp.展开更多
CVD polycrystalline diamond surfaces were etched using reactive ion etching system with either a conventional stainless steel electrode or MgO sintered ceramic containing electrode. The micro-needle array of high aspe...CVD polycrystalline diamond surfaces were etched using reactive ion etching system with either a conventional stainless steel electrode or MgO sintered ceramic containing electrode. The micro-needle array of high aspect on diamond substrate surfaces obtained with MgO electrode was fabricated by using back-sputtering from MgO electrode. The RMS roughness of diamond substrate surfaces obtained with MgO electrode is higher than those obtained with stainless steel electrode. The secondary electron emission coefficient in Ne gas of the diamond obtained with MgO electrode was twice that obtained with the stainless steel electrode.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2022YFA1204203 and 2022YFA1204201)Opening Fund of the State Key Laboratory of Optoelectronic Materials and Technologies at Sun Yat-sen University(No.OEMT-2023-KF-01)+1 种基金National Natural Science Foundation of China(Nos.61971463,82272131,and 82202960)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515010537).
文摘Flat-panel X-ray sources(FPXSs)have many advantages in terms of compactness and low-dose imaging,enhancing their capability for novel X-ray applications.Experimental analysis of the X-ray characteristics and optimizing the anode panel of an FPXS are time-consuming,expensive,and sometimes impractical.In this study,a FPXS was prepared using a ZnO nanowire cold cathode and a molybdenum film anode target.Monte Carlo(MC)simulations were utilized to optimize the anode panel and obtain the average fluence,average energy,and spatial distribution of the X-rays for the ZnO nanowire FPXS.The accuracy of the MC simulations was verified by comparing the measured and simulated energy spectra.Optimization of the anode target considers the material,thickness,and morphology,whereas optimization of the substrate focuses on the material and thickness.The results show that the difference between the positions of the K-shell peaks in the measured and simulated energy spectra is within 0.26 keV.At the acceleration voltages of 30 kV,60 kV,and 90 kV,the optimal thicknesses of the tungsten array anode were 0.65μm,2.45μm,and 5μm,respectively,while the molybdenum array anode has the optimal thicknesses of 1.45μm,5.25μm,and 24μm,respectively.The microsemi-ellipsoidal anode with a recessed design showed a 5%increase in the transmitted X-ray fluence compared with the film target.The sapphire substrate with a thickness of 0.78 mm exhibits a mechanical strength comparable to that of a glass substrate with a thickness of 3 mm,implying that the former can increase the average X-ray fluence by reducing the filtration of X-rays.The findings of this study provide valuable guidance for the fabrication and optimization of the ZnO nanowire FPXS.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB933603)the National Natural Science Foundation of China(Grant Nos.U1134006 and 61101041)
文摘In order to develop miniaturized and integrated electron vacuum devices, the electron beam modulation in a field- emission （FE） electron gun based on carbon nanotubes is researched. By feeding a high-frequency field between the cathode and the anode, the steady FE electron beam can be modulated in the electron gun. The optimal structure of the electron gun is discovered using 3D electromagnetism simulation software, and the FE electron gun is simulated by PIC simulation software. The results show that a broadband （74-114 GHz） modulation can be achieved by the electron gun with a rhombus channel, and the modulation amplitude of the beam current increases with the increases in the input power and the electrostatic field.
基金National Natural Science Foundations of China(No.60976058,No.61274078)Natural Science Research Project of Henan Province Education Department,China(No.2009B510019)
文摘With high effective screen-printing technique, a new triode field emission display (FED)with enhanced petaling cold cathode was fabricated. For enhancing the field emission performance,a series of improved measures was adopted in the fabrication course. Seen from the fabrication structure of enhanced petaling cold cathode,the bar conducting electrode and the petaling bottom electrode were fabricated with the sintered silver slurry on cathode glass faceplate. The luminescence image with green phosphor was displayed for the sealed enhanced petaling cold cathode FED. The measured results showed that the enhanced petaling cold cathode had good field emission performance. The enhanced petaling cold cathode FED possessed low turn-on electric-field of 1. 95 V /μm,large emission current of 1 389. 6 μA,and high luminance brightness of 1 520 cd /m2 .
基金supported by the National Natural Science Foundation of China(Grant Nos.61474110,61377020,61376089,61223005,and 61176126)the Open Project of the Key Laboratory of Nano-devices and Applications,China(Grant No.13ZS04)the National Science Fund for Distinguished Young Scholars,China(Grant No.60925017)
文摘The field emission characteristics of the AlN thin films with micro-scaled cold cathode structures are tested in the high vacuum system. The aluminum nitride （A1N） thin films with a thickness of about 100 nm are prepared on the n-type 6H-SiC （0001） substrate at 1100℃ by metal organic chemical vapor deposition （MOCVD） under low pressure. The I-V curves and surface micro-images of undoped and Si-doped AlN films are investigated. From the I-V and Fowler-Nordheim plots, it can be seen that the Si-doped AlN shows better field emission characteristics compared with the undoped AlN sample. The obtained turn-on field is 6.7 V/μm and the maximum emission current density is 154 mA/cm2 at 69.3 V for the Si- doped AlN film cathode after proper surface treatment. It is proposed that the relatively low electric resistivity of Si-doped AlN films is significant for electron migration to the surface region, and their rougher surface morphology is beneficial to a higher local electric field enhancement for the field emission.
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supported by the National High Technology Research and Development Program of China
文摘This paper mainly investigates plasma characterization on carbon fiber cathodes with and without cesium iodide （CsI） coating powered by a - 300 ns, - 200 kV accelerating pulse. It was found that the CsI layers can not only improve the diode voltage, but also maintain a stable perveance. This indicates a slowly changed diode gap or a low cathode plasma expansion velocity. By spectroscopic diagnostics, in the vicinity of the cathode surface the average plasma density and temperature were found to be -3×10^14 cm^-3 and - 5 eV, respectively, for an electron current density of - 40 A/cm^2. Furthermore, there exists a multicomponent plasma expansion toward the anode. The plasma expansion velocity, corresponding to the carbon and hydrogen ions, is estimated to be - 1.5 cm/μs. Most notably, Cs spectroscopic line was obtained only at the distance - 0.5 mm from the cathode surface. Carbon and hydrogen ions are obtained up to the distance of 2.5 mm from the cathode surface. Cs ions almost remain at the vicinity of the cathode surface. These results show that the addition of CsI enables a slow cathode plasma expansion toward the anode, providing a positive prospect for developing long-pulse electron beam sources.
基金Project supported by the National High Technology Research and Development Program of China
文摘The remaining challenges, confronting high-power microwave （HPM） sources and pulsed power generators, stim- ulate the developments of robust relativistic electron beam sources. This paper presents a carbon fibre cathode which is tested in a single pulsed power generator. The distribution and the development of cathode plasma are observed by time-and-space resolved diagnostics, and the uniformity of electron beam density is checked by taking x-ray images. A quasistationary behaviour of cathode plasma expansion is observed. It is found that the uniformity of the extracted electron beam is satisfactory in spite of individual plasma jets on the cathode surface. These results show that carbon fibre cathodes can provide a positive prospect for developing a high-quality electron beam.
文摘The Ba x-0.05MgAl 10O 16+x∶Eu 2+ 0.05 (0.88≤x ≤1.02) phosphors with different Ba 2+ content and the Ba 0.85MgAl 10O 16.94∶Eu 2+ 0.09 phosphors with different fluxes (BaF 2, MgF 2, AlF 3, BaCl 2, MgCl 2, AlCl 3, H 3BO 3) were prepared by high temperature solid-state reaction method and their luminescence characteristics were studied under 254 nm excitation and vacuum ultraviolet (VUV) excitation. With the increase of the Ba 2+ content, there is an increase in the emission intensity, and when x=0.94, it reaches a maximum. Then, as the Ba 2+ content increases, the emission intensity slowly falls. The fluorides have better flux-effects than chlorides and H 3BO 3. The possible mechanism in the process of particle growth was discussed when fluorides were used as fluxes. The effect of the activator concentration on this system was also investigated. The quenching concentration is 0.13 mol in per mole host.
基金supported by National Natural Science Foundation of China(Nos.11505040,11261140326,11405038 and 51577043)China Postdoctoral Science Foundation(Nos.2016M591518,2015M570283)HIT.NSRIF under Grant No.2017008
文摘Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance（ECR） system for the ‘whistler/chorus＇ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén＇ wave study. The parameters of ‘whistler/chorus＇ waves and ‘Alfvén＇ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt＇ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.
文摘High calcination temperature is an important factor in the preparation process of CeMgAl 11O 19∶Tb 3+. To decrease the temperature, different fluxes (H 3BO 3, MgF 2 and AlF 3) were tested in order to compare their influence on the luminescence property and particle size distribution of CeMgAl 11O 19∶Tb 3+. The result shows that when the content of MgF 2 is 0.1 mol/mol, the intensity of luminescence can attain a maximum. Furthermore, MgF 2 can improve the particle size quality of the phosphor. So MgF 2 can take the place of the conventional flux H 3BO 3 to prepare high quality CeMgAl 11O 19∶Tb 3+ phosphor. In addition, the relation between phosphor property and content of AlF 3 was also studied. The crystal structure of the phosphor was analyzed by XRD method. The phase composition analysis shows that the reason of decrease of the brightness of CeMgAl 11O 19∶Tb 3+ phosphor is the emergence of TbAlO 3 and α-Al 2O 3 during the preparation process.
文摘PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circuit is used to conduct simulations, leading to a precise modeling. A library is configured through modeling and its accuracy is verified through simulations for widely used and representative lamps such as CCFL, fluorescent lamps, HID lamps, and electrodeless fluorescent lamps. On the basis of experiments, a lamp simulation is also performed using PSPICE, which allows us to take advantage of the lamp library easily. Also, PSPICE model driven by an electric equivalent circuit of a piezoelectric transformer is presented. In order to confirm this model to be effective, an independent model of CCFL driving circuit is used to conduct simulations, leading to a precise modeling. In addition, a new type of electronic ballast is proposed, which allows 35 W-class(T5-class) fluorescent lamp to work. This system is built by a rectifier which has improved power factor and half-bridge series resonant inverter. Also, with size of 27.5 mm high, 27.5 mm wide and 2.5 mm thick, the produced piezoelectric transformer has a high step-up ratio, through which it is possible for the electric ballast circuit to be lighter, smaller and more efficient. After the produced ballast is used to drive the fluorescent lamp for 25 min, it yields 0.95 in power factor correction, 86% in efficiency, 35.07 W in output voltage and 20.5 °C in temperature increase while meeting the characteristics of the 35 W-class fluorescent lamp.
文摘CVD polycrystalline diamond surfaces were etched using reactive ion etching system with either a conventional stainless steel electrode or MgO sintered ceramic containing electrode. The micro-needle array of high aspect on diamond substrate surfaces obtained with MgO electrode was fabricated by using back-sputtering from MgO electrode. The RMS roughness of diamond substrate surfaces obtained with MgO electrode is higher than those obtained with stainless steel electrode. The secondary electron emission coefficient in Ne gas of the diamond obtained with MgO electrode was twice that obtained with the stainless steel electrode.
