300px, Nuclear gas core closed cycle rocket engine diagram, nuclear "light bulb" A nuclear lightbulb is a hypothetical type of spacecraft engine using a gaseous fission reactor to achieve

nuclear propulsion Nuclear propulsion includes a wide variety of propulsion methods that use some form of nuclear reaction as their primary power source. The idea of using nuclear material for propulsion dates back to the beginning of the 20th century. In 1903 it was ...

. Specifically it would be a type of gas core reactor rocket that uses a

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

wall to separate nuclear fuel from

coolant A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosi ...

/ propellant. It would be operated at temperatures of up to 22,000°C where the vast majority of the

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions o ...

emissions would be in the hard

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

range. Fused silica is almost completely transparent to this light, so it would be used to contain the

uranium hexafluoride Uranium hexafluoride (), (sometimes called "hex") is an inorganic compound with the formula UF6. Uranium hexafluoride is a volatile white solid that reacts with water, releasing corrosive hydrofluoric acid. The compound reacts mildly with alumin ...

and allow the light to heat

reaction mass Working mass, also referred to as reaction mass, is a mass against which a system operates in order to produce acceleration. In the case of a chemical rocket, for example, the reaction mass is the product of the burned fuel shot backwards to prov ...

in a rocket or to generate electricity using a

heat engine In thermodynamics and engineering, a heat engine is a system that converts heat to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state ...

photovoltaics Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially ...

. This type of reactor shows great promise in both of these roles.

Rocket engine

As a rocket engine it, like all nuclear rocket designs, can greatly exceed the exhaust speed and

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...

of a chemical rocket. However, it also does not involve the release of any radioactive material from the rocket, unlike open cycle designs which would cause

nuclear fallout Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioac ...

if used in a planetary atmosphere (e.g. Project Orion). The theoretical

(''I''_sp) range from 1500 to 3000 seconds.

Electrical power generation

As a method to generate electricity, nuclear lightbulbs are extremely efficient because higher-temperature heat contains more

Gibbs free energy In thermodynamics, the Gibbs free energy (or Gibbs energy; symbol G) is a thermodynamic potential that can be used to calculate the maximum amount of work that may be performed by a thermodynamically closed system at constant temperature and ...

than the low-temperature heat produced in current fossil-fuel plants and water-cooled nuclear reactors.

References

* * * {{spacecraft propulsion Nuclear reactors Nuclear spacecraft propulsion Nuclear technology