To answer my own question: this is basically the concept behind nuclear ramjets (e.g. https://en.wikipedia.org/wiki/Project_Pluto https://en.wikipedia.org/wiki/

To answer my own question: this is basically the concept behind nuclear ramjets (e.g. https://en.wikipedia.org/wiki/Project_Pluto https://en.wikipedia.org/wiki/Project_Pluto). "Going nuclear" solves the energy density problem here ... the same thing with LiIon batteries would just not work (equally well). Apparently, electric ramjets for spacecraft propulsion is an active field of research: https://www.sciencedirect.com/science/article/pii/S1877705817314534 https://www.sciencedirect.com/science/article/pii/S187770581...