Reply To: EmDrive + Focus Fusion = Space Access for all?

[Tulse]

belbear wrote: A FF powered scramjet does not do chemical combustion at all, so this problem does not pose itself, because it would work by simple heating of incoming air (using either electricity, X-rays or ion beam) And that always work.
Instead of fuel injection it could be using a tungsten heat exchanger, operating at very high temperature (2000°C) to transfer heat from the source to the airflow.

Thanks for clarifying that. I wonder if instead of a heat exchanger if something like a plasma torch would be more efficient, as it would use the FF electricity directly.

I’m also still not clear on the power required, however. What kind of power density does one have to reach to match that of hydrocarbon fuel? Is such density practically achievable?

I also wonder if FF won’t be far more useful in deep space, where low thrust electric propulsion systems are more practical, and where one might not need a lot of the support gear on needs in an atmosphere. For example, I presume it wouldn’t be necessary to have a vacuum pump to keep the reaction chamber evacuated in space, or to have the reaction chamber heavily reinforced to fight against implosion from atmospheric pressure. I would think a space-based FF reactor could be much lighter and smaller in space. (The one issue that might be more of a problem is dealing with the waste heat, as it it more difficult to radiate it away in a vacuum.) I would also think that the inherent simplicity of the system would be attractive, relative to fission reactors that require complex systems to turn their heat into electricity.