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RE: Graphene --- As A Means Of Fine-Tuned Spacecraft Propulsion --- Interesting Properties of Graphene
Hi, very interesting post. I enjoyed reading and learning.
A couple of questions:
I assume that if you keep on shining a laser at graphene it will become depleted of electrons? So in that sense the amount of propulsion available from a set quantity of graphene is limited, isn't it?
How many photons does it take to eject one electron out of graphene?
I assume it depends on the photon's wavelength?
Assuming a sheet of graphene, where would you have to aim the laser at to get the best propulsion effect?
Hello, I'm glad you enjoyed the article, and thanks for the good questions.
The Graphene will need lose electrons as a result, there would be a limit to the propulsion as a result. An electron capturing device could be utilised, based on a magnetic field. However the purpose of this propulsion is to be used in the final sequence of a manoeuvre. The manoeuvre would be completed before the deplition occurs.
The wavelength of radiation gives each photon it's specific energy, these are absorbed by the Graphene. The ejection process occurs due to "hot electrons", and not like the photoelectric effect.
A sheet would not be used for the propulsion but a carefully constructed bulk-graphene-sponge. You would want to avoid shining the laser on the edges and more towards the central area, but the geometry is not too important.
I'm curious as to how the spacecraft is being neutralized. It seems to me like propulsion via electrons would just build up a huge charge on the spacecraft, requiring higher energy photons to eject new electrons and maybe causing arcing.
It's not possible exactly for this reason to be a continuous source of propulsion, but could operate for short periods of time and provide the fine propulsion. This is something that's being developed with projects due to start this year.