Optimizing the e-beam profile of a single carbon nanotube field emission device for electric propulsion systems

Mologni, Juliano Fujioka; Alves, Marco Antonio Robert; Braumgratz, Filipe; Fonseca, Edson; Siqueira, Cesareo L. R.; Braga, Edmundo Silva

doi:10.5028/jatm.2010.02010915

Abstract:

Preliminary studies on field emission (FE) arrays comprised of carbon nanotubes (CNT) as an electron source for electric propulsion system show remarkably promising results. Design parameters for a carbon nanotube (CNT) field-emission device operating on triode configuration were numerically simulated and optimized in order to enhance the e-beam focusing quality. An additional focus gate (FG) was integrated to the device to control the profile of the emitted e-beam. An axisymmetric finite element model was developed to calculate the electric field distribution on the vacuum region and a modified Fowler-Nordheim (FN) equation was used to evaluate the current density emission and the effective emitter area. Afterward, a FE simulation was employed in order to calculate the trajectory of the emitted electrons and define the electron-optical properties of the e-beam. The integration of the FG was fully investigated via computational intelligence techniques. The best performance device according to our simulations presents a collimated e-beam profile that suits well for field emission displays, magnetic field detection and electron microscopy. The automated computational design tool presented in this study strongly benefits the robust design of integrated electron-optical systems for vacuum field emission applications, including electrodynamic tethering and electric propulsion systems.

Keywords:
Electric propulsion; Carbon nanotube; Finite element analysis

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REFERENCES

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» https://doi.org/10.1088/0957-4484/18/48/485702
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Publication Dates

Publication in this collection
Jan-Apr 2010

History

Received
08 Mar 2010
Accepted
25 Mar 2010

This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

[1] Chen, P.Y., et al, 2007, "Optimal design of integrally gated CNT field-emission devices using a genetic algorithm", Nanotechnology, Vol. 18, 10p. doi: 10.1088/0957-4484/18/39/395203.
» https://doi.org/10.1088/0957-4484/18/39/395203.

[2] Chernozatonskii, L.A., et al, 1995, "Electron field emission from nanofilament carbon films", Chem Phys Lett, Vol. 233, pp. 63-68.

[3] Choi, J.E., et al, 2004, "Carbon nanotube field emitter arrays having an electron beam focusing structure", Appl Phys Lett, Vol. 84, pp. 1022-1025.

[4] De Heer, W.A., Châtelain, A., Ugarte, D., 1995, "A carbon nanotube field-emission electron source", Science, Vol. 270, pp.1179-1180.

[5] Edgcombe, C.J., Valdre, U., 2001, "Microscopy and computational modeling to elucidate the enhancement factor for field electron emitters", J Microsc, Vol. 203, pp. 188-194.

[6] Fransen, M.J., Rooy, T.L., Kruit, P., 1999, "Field emission energy distribution from individual carbon nanotube", Appl Surf Sci, Vol. 146, pp. 312-327.

[7] Itoh, J. Uemara S.K., Kanemaru S., 1998, "Three-dimensional vacuum magnetic sensor with a Si emitter tip", J Vac Sci Technol B, Vol. 16, pp. 1233-1235.

[8] Lei, W., Yang, G., Xie, M., 2004, "Study of the triode structure in a field emission display element", J Vac Sci Technol B, Vol. 24, pp. 962-964.

[9] Liao, K.P., Hu, Y., Lin, T.L., 2007, "Simulation studies of self-focusing carbon nanotube field emitter", J Vac Sci Technol B, Vol. 25, pp. 84-86.

[10] Marreses-Reading, C., et al, 2002, "Field emission array cathode material selection for compatibility with electric propulsion applications", Nasa JPL Technical Report, No. 8523, 17p.

[11] Mologni, J.F., et al, 2006, "Numerical study on performance of pyramidal and conical isotropic etched single emitters", Microelectronics Journal, Vol. 37, pp. 152-157.

[12] Niemman, D.L., et al, 2007, "Effects of cathode structure on the field emission properties of individual multi-walled carbon nanotube emitters", Nanotechnology, Vol. 18. doi: 10.1088/0957-4484/18/48/485702.
» https://doi.org/10.1088/0957-4484/18/48/485702

[13] Okawa, Y., et al, 2007, "An experimental study on carbon nanotube cathodes for electrodynamic tether propulsion", Acta Astronautica, Vol. 61, pp. 989-994.

[14] Rinzler, A.G., et al, 1995, "Unraveling nanotubes: field emission from an atomic wire", Science, Vol. 269, pp.1550-1553.

[15] Seidl, A., et al, 2000, "Geometry effects arising from anodization of field emitters", J Vac Sci Technol B, Vol. 2, pp. 929-932.

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