maybe so. i don't know about attritable for the first applications though. may long range or duration oversight. a large % of the cost is these specialty cells which have not been scaled up to mass production. in the denominator is the intensity of light we can produce, which is based on how high a temperature we can drive, there's a very nonlinear brightness vs temperature. but at 100 suns or so we can get near to $1/W on the cells at startup scale

Or turn it around a bit. If the entire device could operate at high pressure, then one could imagine putting it inside a jet or rocket engine. Feed it compressed fuel/air mix, burn, extract some energy via thermophotovoltaics, and blast the exhaust out a nozzle or use it to spin a turbine to drive a bypass fan.

An obvious down side is that most jets have very, very high fuel flow and power output, and the area required to extract enough electricity to make this whole exercise worthwhile may be excessive. Also, a lot of military applications are not going to like that sodium illuminant lighting up the exhaust gasses, scattering radar, or otherwise making the plane more visible.

edit: I see that there’s an effort to recirculate the sodium. Maybe that’s enough.

The end goal isn't to preheat the fuel, it's to keep the heat from escaping, because you want all the heat to go into the sodium.

The heat is being used to generate electricity.

Fuel is burned to head sodium, if you are getting too much heat for your taste you can burn less fuel. It is kinda the goal of the exercise.

But in any case, I believe that the more you heat sodium, the more light it emits, probably there is a practical limit on an incoming heat power after which the thing will go boom, but before that it will follow some roughly linear law: the more heat energy in, the more light comes out. Though I'm not a physicist, so I make be wrong, even if I do not see how I can be wrong.