研究目的
To address the current decay issue in carbon nanotube forests through in-situ pre-heating to remove oxidizing agents such as water, which is known to be a strong CNT etchant at high temperatures.
研究成果
Pre-heating a CNT forest to 300 °C before inducing Heat Trap conditions from laser spot heating demonstrates stable emission current over a few hours, with evidence that adsorbed reactant gases within the CNT forest may be the primary cause of decay in the emission current. This is a promising step towards producing CNT-based thermionic emitters with a long lifetime for various applications.
研究不足
The study suggests that full outgassing of the CNT forest is necessary to investigate other possible contributors to current instability and causes of variation in thermionic current behavior at different regions of the CNT forest sidewall.
1：Experimental Design and Method Selection:
The study involved pre-heating CNT forests to remove adsorbed gases and observing the effect on thermionic emission current stability.
2：Sample Selection and Data Sources:
Vertically aligned multi-walled CNT forests grown using atmospheric-pressure chemical vapor deposition.
3：List of Experimental Equipment and Materials:
Custom sample holder made of Invar 36, CVD monolayer graphene on quartz for resistive heating, K-type thermocouple, diode thermometer, quadrupole residual gas analyzer, 532 nm continuous-wave laser beam, ITO coated on quartz glass as collector.
4：Experimental Procedures and Operational Workflow:
Pre-heating CNT forests to 300 °C for 4 hours in high vacuum, then inducing thermionic emission by laser illumination and measuring the emission current.
5：Data Analysis Methods:
Observation of changes in gas composition within the vacuum chamber and correlation with emission current stability.
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