Lowering of Ignition Voltage of Gas Discharge by Using Carbon Nanotube Electrodes and Its Application to Fluorescence Tubes

采用碳纳米管（CNT）阴极进行气体放电实验，得到以下结果.当电极之间的差距（d）为0.1mm时，与不锈钢（SUS）阴极相比，CNT阴极在较低的电压下点燃气体放电，而与氩气（Ar）压力（100 Pa？1700Pa）的压力下进行。对于较宽的间隙（即，d=1mm和10mm），但是，点火电压的差异变小，并且CNT阴极在更高的气压下显示出更高的电压.点火电压取决于阴极金属上碳纳米管薄膜的结构和织构。电弧放电法制备的喷射沉积单壁和多壁碳纳米管具有一定的降低点火电压的作用，而等离子体CVD法在阴极金属表面形成的高密度垂直排列的碳纳米管在一定条件下具有提高点火电压的作用，但几乎没有降低点火电压的作用.当碳纳米管薄膜用于阳极时，点火电压提高.关于维持放电的电压，当差距较窄（d=0.1 mm和1 mm）时，CNT阴极可以在较低的Ar气体压力（100 Pa至1200 Pa）下以比SUS阴极低的电压维持放电。相反，对于宽间隙（d=10 mm），CNT阴极需要更高的电压才能在整个气压范围内维持放电.放电电压随杂质气体分压的变化而变化，表明存在潘宁效应.在放电实验后，CNT膜经常从阴极上剥落，总之，通过使用CNT阴极，观察到气体放电电压在某种程度上降低，但电压的降低仅为10%。对于CNT阴极的工业应用，气体放电电压以及CNT膜的防剥离保护是必要的。

Gas discharge experiment was performed using carbon nanotube (CNT) cathodes, and the following results were obtained.1. When the gap between electrodes (d) was 0.1mm, the CNT cathode ignited gas discharge at a lower voltage compared with a stainless steel (SUS) cathode, irrespective of argon (Ar) gas pressures (100Pa ? 1700Pa) employed in the present experiment. For the wider gap (i.e., d=1mm and 10mm), however, the difference in the ignition voltage became small, and the CNT cathode showed higher voltages at higher gas pressure.2. The ignition voltage was dependent on the structure and texture of CNT films on the cathode metal. Spray deposited single-wall and multi-wall CNTs that were produced by arc-discharge method exhibited some effects on lowering the ignition voltage, while vertically-aligned CNTs with high density formed on the cathode metal by plasma-CVD method, rarely showed the lowering effect but raised the ignition voltage in some conditions.3. When CNT films were used on the anode, the ignition voltage was raised.4. Concerning the voltage for sustaining discharge, CNT cathodes could sustain discharge with lower voltage than the SUS cathode at low pressure of Ar gas (100Pa〜1200pa) when the gap was narrow (d=0.1 mm and 1 mm). For the wide gap (d=10 mm), on the contrary, CNT cathodes needed higher voltage to sustain discharge over the whole range of pressure.5. The discharge voltage changed by the partial pressure of impurity gases, suggesting the Penning effect.6. CNT films often peeled off the cathode after the discharge experiment.In summary, lowering of gas discharge voltages was observed to some extent by using CNT cathode, but the reduction in the voltage was only 10%. For the industrial application of CNT cathodes to gas discharge voltage but also protection of CNT films against peeling-off are necessary.