碳纤维阴极的场致发射特性实验研究
Experimental research on field emission of carbon fibe
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摘要: 研究了具有一定导电性能的碳纤维的直流场致发射电子束特性,实验分别在大气环境、低真空(10-1 Pa)及高真空(10-5 Pa)环境下进行。实验结果表明,碳纤维具有一定的场致发射能力,并且发射特性和发射环境的真空度密切相关。在大气环境下,发射电子束流与所施加的电压符合Fowler-Nordheim关系,当电压为7 kV,电流为61.4 μA时,根据Fowler-Nordheim定理推算出碳纤维场致发射场增强因子为3.75×105。在低真空条件下阳极只收集到微弱的电流;在高真空条件下,阴极发射明显,在较低电压下就能观测到阳极电流,放电前阳极最高电流是大气条件下的3~4倍,发射的束流大小和所施加在尖端的电压关系接近Child-Langmiur定律。Abstract: Electric carbon fiber is a promising material to emit cold electron under intensive electric field. Experiment was conducted to test carbon fiber’s emission at the pressures of 0.1 MPa, 10-1 Pa and 10-5 Pa. The diode gap between the fiber tip and the electron collecting anode was about 5 mm. In atmosphere, the applied voltage and the emitted current have a Fowler-Nordheim relation. According to Fowler-Nordheim theorem, the field intensified factor was 3.75×105 when the voltage was 7 kV and the current was 61.4 μA. In low vacuum (about 10-1 Pa) condition, the anode collected current only less than 10 μA under 20 kV. In high vacuum (about 10-5 Pa) condition, the anode collected larger anode current up to 300 μA without flashover, the relation between voltage and current was close to the
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Key words:
- carbon fiber cathode /
- field emission /
- vacuum /
- plasma
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