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Investigation on the Plasma-Induced Emission Properties of Large Area Carbon Nanotube Array Cathodes with Different Morphologies

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ABSTRACT

Large area well-aligned carbon nanotube (CNT) arrays with different morphologies were synthesized by using a chemical vapor deposition. The plasma-induced emission properties of CNT array cathodes with different morphologies were investigated. The ratio of CNT height to CNT-to-CNT distance has considerable effects on their plasma-induced emission properties. As the ratio increases, emission currents of CNT array cathodes decrease due to screening effects. Under the pulse electric field of about 6 V/μm, high-intensity electron beams of 170–180 A/cm2 were emitted from the surface plasma. The production mechanism of the high-intensity electron beams emitted from the CNT arrays was plasma-induced emission. Moreover, the distribution of the electron beams was in situ characterized by the light emission from the surface plasma.

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The CCD images of four kinds of CNT array cathodes that are emitting: a 4 μm, b 7 μm, c 14 μm, d 16 μm.
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Figure 4: The CCD images of four kinds of CNT array cathodes that are emitting: a 4 μm, b 7 μm, c 14 μm, d 16 μm.

Mentions: Figure 4 shows the CCD images of the four kinds of CNT array cathodes that are emitting. Compared with the CCD image of the cathodes that are not emit (shown in Figure 1b), it can be found that the CCD images of Figure 4 have bright light. The bright light captured by the CCD camera was considered as the light emission from plasmas on the cathode surface [8-10]. The luminescent zones on the cathode surface are emission sites. The CCD images show the spatial distribution of the emission sites and the plasmas. The distribution of the emission sites on the CNT arrays is very similar to that of the coated CNT cathode [12,13]. Figure 4a is the CCD image of the 4-μm height cathode. The luminescence on the cathode surface is very intense and uniform. The CCD image shows that the emission current is very intense and almost whole cathode surface can emit electrons. The luminescence of the 7-μm height cathode becomes weak obviously relative to the 4-μm height cathode, as shown in Figure 4b. It can be seen that many separate emission sites distribute on the cathode surface. The brightness and area of the luminescence are less than these of the 4-μm height cathode. It has been known that the 4-μm height CNT arrays have the higher emission current. Therefore, the CCD images can reflect the intensity of emission currents. The CCD images of the 14- and 16-μm height cathodes are shown in Figure 4c and Figure 4d, respectively. The brightness and area of luminescence reduce in contrast with that of the previous short CNT array cathodes. The emission area of the 14-μm height cathode is larger than that of the 16-μm height cathode. The emission current is in direct proportion with the brightness and area of light emission from the plasma. The CCD images reconfirmed that the emission currents of the CNT array cathodes decrease with the increase in the ratios of CNT height to CNT-to-CNT distance.


Investigation on the Plasma-Induced Emission Properties of Large Area Carbon Nanotube Array Cathodes with Different Morphologies
The CCD images of four kinds of CNT array cathodes that are emitting: a 4 μm, b 7 μm, c 14 μm, d 16 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211494&req=5

Figure 4: The CCD images of four kinds of CNT array cathodes that are emitting: a 4 μm, b 7 μm, c 14 μm, d 16 μm.
Mentions: Figure 4 shows the CCD images of the four kinds of CNT array cathodes that are emitting. Compared with the CCD image of the cathodes that are not emit (shown in Figure 1b), it can be found that the CCD images of Figure 4 have bright light. The bright light captured by the CCD camera was considered as the light emission from plasmas on the cathode surface [8-10]. The luminescent zones on the cathode surface are emission sites. The CCD images show the spatial distribution of the emission sites and the plasmas. The distribution of the emission sites on the CNT arrays is very similar to that of the coated CNT cathode [12,13]. Figure 4a is the CCD image of the 4-μm height cathode. The luminescence on the cathode surface is very intense and uniform. The CCD image shows that the emission current is very intense and almost whole cathode surface can emit electrons. The luminescence of the 7-μm height cathode becomes weak obviously relative to the 4-μm height cathode, as shown in Figure 4b. It can be seen that many separate emission sites distribute on the cathode surface. The brightness and area of the luminescence are less than these of the 4-μm height cathode. It has been known that the 4-μm height CNT arrays have the higher emission current. Therefore, the CCD images can reflect the intensity of emission currents. The CCD images of the 14- and 16-μm height cathodes are shown in Figure 4c and Figure 4d, respectively. The brightness and area of luminescence reduce in contrast with that of the previous short CNT array cathodes. The emission area of the 14-μm height cathode is larger than that of the 16-μm height cathode. The emission current is in direct proportion with the brightness and area of light emission from the plasma. The CCD images reconfirmed that the emission currents of the CNT array cathodes decrease with the increase in the ratios of CNT height to CNT-to-CNT distance.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Large area well-aligned carbon nanotube (CNT) arrays with different morphologies were synthesized by using a chemical vapor deposition. The plasma-induced emission properties of CNT array cathodes with different morphologies were investigated. The ratio of CNT height to CNT-to-CNT distance has considerable effects on their plasma-induced emission properties. As the ratio increases, emission currents of CNT array cathodes decrease due to screening effects. Under the pulse electric field of about 6 V/μm, high-intensity electron beams of 170–180 A/cm2 were emitted from the surface plasma. The production mechanism of the high-intensity electron beams emitted from the CNT arrays was plasma-induced emission. Moreover, the distribution of the electron beams was in situ characterized by the light emission from the surface plasma.

No MeSH data available.