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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Stability of carbon nanotube cold cathode electron beam (C-beam) with vacuum brazing process
摘要： A modularization of electronic parts in electrical devices is a key feature for system integration. Especially, x-ray tube fabrication process has been stayed in an obsolete manner due to the utilizing of classical thermionic x-ray sources. But cold cathode emitters such as carbon based materials with nanoscale dimension are expected to replace the conventional wired tungsten filaments due to their outstanding electrical and mechanical properties. To facilitate cold cathode emitter as an x-ray source, state of the arts bonding techniques are required. In this study, carbon nanotube grown Si wafers were successfully bonded to the metal carrier via vacuum brazing process and no electrical degradation of CNT (carbon nanotubes) emitters were observed after the process. Finally, we evaluated the stability of electron beam current density for device reliability. We expect that the cost-effective and facile technique could be applied for cold cathode based x-ray tube manufacturing process.
关键词： carbon nanotubes (CNTs),brazing,x-ray tube,junction,cold cathode
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Development of ultrafast electronic oscillator by exploiting advantage of cold cathodes
摘要： Origin of the upper frequency limit in vacuum devices was investigated. New analytical theory was developed for a simple vacuum diode in which electrons are launched on a cathode surface and are accelerated or decelerated toward an anode by a DC-biased AC electric field. We found electrons or charge carriers collectively arrives on the anode surface regardless of the frequency of the AC electric field if a diode configuration and the electric field are manipulated with some parameter values given by our theoretical calculations. The extraordinary collective behavior of electrons exceeds the transit-time limit which has given the upper frequency barrier in transitional electronic devices. For the novel electron devices, cold cathodes which emit electrons by the field emission is preferable to conventional thermionic cathodes because of the high nonlinearity between the current and the applied voltage. We are expanding the principle to develop a novel electronic oscillator that can operate in the terahertz frequency regime which demands ultrafast physical phenomenon.
关键词： ultrafast,vacuum device,cold cathode,electronic oscillator,transit-time limit
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - CNT field emitter based high performance x-ray source
摘要： We fabricated the cold cathode x-ray source composed of point-type CNT field emitter, mesh gate electrode, e-beam focusing lens and W anode. The point-type CNT field emitter was made by CNT film with a triangular tip shape. Field emission properties measured in triode configuration showed the low turn-on and threshold electric fields, the high emission current and focused electron beam spot. The CNT field emitter based cold cathode x-ray source reveals high resolution x-ray images. We demonstrated that the point-type CNT emitter is suitable candidate for the high performance cold cathode x-ray sources.
关键词： cold cathode x-ray source,triode structure,field emission,carbon nanotube filed emitter
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Properties of one-free standing CNT cold cathode for high resolution devices
摘要： A high resolution imaging technology has been developed with cold cathode electron source. Just grown carbon nanotube (CNT) field emitter was prepared for electron microscope. The angular current density, virtual source and lifetime of the emitted electrons were evaluated with three different categorized. An estimated beam brightness was extracted from the experimental value. With the geometric field enhancement factor, reduced brightness (Br) is depend on and enhanced brightness with higher geometric factors. The reduced brightness of 1.42 × 1011 A · m-2sr-1V-1 at 1,100V of applied voltage obtained.
关键词： CNT cold cathode,High brightness,Electron microscopy
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field Emission Performance of Boron Nitride Nanotube Emitters According to Vacuum Pressure
摘要： Field emission performance of boron nitride nanotube filtration-transfer fabricated by simple method, were evaluated according to vacuum pressure to estimate its potential use for robust electron sources. Even though there is little change in the current density-electric field characteristics, the stability test for a relatively long time shows somewhat large degradation at a vacuum pressure of over 10-6 Torr. To investigate a key factor of the degradation, we changed the vacuum ambient from air to argon. Under argon ambient condition, the current degradation and fluctuation rates were almost the same as those measured under air ambient at a vacuum pressure of 10-5 Torr. Consequently, ion bombardment dominantly induced the current degradation of the BNNT field emitters rather than oxidation effect.
关键词： Boron nitride nanotube,field emitter,film emitter,cold cathode
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - High performance x-ray source using point-typed CNT field emitter
摘要： The high performance cold cathode x-ray source was fabricated by using the point-typed CNT field emitter. The cold cathode x-ray source consists of the CNT point emitter, the metal mesh gate electrode, the metal hole focusing lens and the tungsten target anode electrode. To fabricate x-ray source, such components were mounted in a SUS vacuum chamber. The fabricated CNT x-ray source showed a good resolution of x-ray images at a low anode current and at a low anode voltage, and also indicated stable operation. We evaluated x-ray images according to the tube voltage and the tube current, respectively.
关键词： point-typed field emitter,carbon nanotube field emitter,metal mesh gate electrode,x-ray image,cold cathode x-ray source,tungsten anode electrode
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Cold Cathode Based Microwave Devices for Current and Future Systems
摘要： We report ongoing efforts to achieve reliable field emitter (FE) cathode operation for high current electron beam generation in RF microwave devices. These efforts include testing of cold cathode traveling wave tubes, high average power cathode-only testing, and evaluating cathode emission variation over long operating periods in a microwave device vacuum environment. Finally, looking toward future needs, emittance reduction is being addressed to allow cold cathode operation in the mm-wave frequency regime.
关键词： field emitter array,TWT,traveling wave tube,microwave amplifier,cold cathode,vacuum electronics
更新于2025-09-23 15:21:21