Laser Processing of Carbon Nanotube (CNT) Fibres and Films – Mr Francisco Orozco
This project aims to develop a customized device capable of producing repeatable, reliable emission cathodes with an emission of more than 10 mA that can be applied as sources of high power microwaves in the Air Force Research Laboratory (AFRL), Directed Energy Directorate. Advancements have been made with the production of FED and ease of handling techniques of CNT material.
Up to date results show the coating process delivers an improvement of emission of 18% compared to unprocessed material. After these results work has commenced on the following points:
Design of process for cathode fabrication
A new process has been developed for the production of these cathodes. The process is: Step 1: Coating to handle the material and improve the emission. Step 2: Laser cutting to desired geometry and dimensions. Step 3: Array alignment and bonding. Step 4: Mounting to copper slabs for field emission testing.
Scalable production route for fibre arrays
Francisco is currently able to reproduce arrays in a repeatable manner using commercially available technology which can be scaled up with relative ease. Arrays have been made using fibres and films. Figure 1. shows an array that was built stacking 3 films using the production process developed. These arrays can be manufactured having repeatable alignment and can have customized geometries. Latest samples made had 8 films stacked giving 48 emission tips. Field emission testing of these will be made in the following 4 months to ensure device reliability.
Francisco is a third year PhD student at the Institute for Manufacturing, University of Cambridge under the supervision of Prof Bill O’Neill and is sponsored by the Air Force of Scientific Research, Air Force Material Command, USAF.
Outputs
Journal Publications
Cahay, M., Murray, P. T., Back, T. C., Fairchild, S., Boeckl, J., Bulmer, J., Koziol, K. K. K. , Gruen, G., Sparkes, M., Orozco, F. and O’Neill, W. (2014). Hysteresis during field emission from chemical vapor deposition synthesized carbon nanotube fibers, Appl. Phys. Lett. 105, 173107.
Fairchild, S. B., Bulmer, J. S., Sparkes, M., Boeckl, J., Cahay, M., Back, T., Murray, P. T., Gruen, G., Lange, M., Lockwood, N. P., Orozco, F., O’Neill, W., Paukner, C. and Koziol, K. K. K. (2014). Field emission from laser cut CNT fibers and films, Journal of Materials Research, 29, 3, 392-402.
Digital Media
Orozco, F. (2015). Laser processing of carbon nanotube fibres and films, PhD project video produced for an informal Centre competition in 2015.
Posters
Orozco, F. (2016). Carbon nanotube based production of field emission cathodes, Poster presentation to the EPSRC Centre for Innovative Manufacturing in Ultra Precision Steering Meeting Committee, 24 February 2016, Cranfield University, UK.
