Metalization of CNT Fibres.
Abstract
The fundamental aim is to make a metal-CNT paper laminate, and optimise the individual properties of the composite, to reduce outgassing and secondary electron emission which limit the performance of high power anodes.The primary issue is local hot spots in the anode material resulting from electrons in a RF device, electron gun or linear accelerator bunching together. When the anode is struck heat is generated at a localised point and depth in the material based on energy distribution.A two-pronged approach is initially proposed, bulk material engineering by the addition of CNTs to the material coupled with laser surface engineering to polish and reduce surface grain (surface texturing could also be applied if appropriate).It is necessary to redistribute the heat into a large rapidly outgassing/ desorption being exponentially dependent on temperature. It is envisaged that a dense, pure CNT paper encased within a metal may be able to facilitate thermal transport parallel to the surface due to phonons traveling along the CNTs, and potentially lower transverse thermal transport due to poor phonon coupling with the metal. Multiple layers of CNT paper would also change the depth of where the electron energy is deposited allowing additional spreading of the heat. The CNT paper could act as a collector for the heated hydrogen and oxygen, etc. to stick to so it does not diffuse through the metal creating a diffusion barrier.Surface grain boundary modification has been demonstrated to reduce outgassing by the reduction of grain boundaries in an active AFSOR grant. The act of laser polishing has a secondary benefit by reducing the cracks in the surface that encourage Langmuir-Hinshelwood desorption (atoms migrating on the surface and have a chemical reaction which causes them to leave the surface).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 09, 2018
- Source ID
- FA95501810033
Entities
People
- William O Neill
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Cambridge