Does Fully Electric Thrusters Exist?

[Paramecium8]

Every type of electric thrusters used in space that i have seen ejects matter to move, even the ionic thrusters use xenom to move, fully electric thrusters exist?,

[EdEarl]

I saw an article about using an on-board microwave transmitter for propulsion. It did not depend on carrying mass to eject; rather, the author said it accelerated virtual particles, which already exist in space. IDK if it works, or for that matter if anyone knows. It is possible to use a laser to push on a light sail, with the laser in Earth or Solar orbit.

[Enthalpy]

Ejected light or radiowaves do provide thrust, but so little... F=P/c where P is the power.

If the necessary electric power comes from solar panels, then you get more thrust from impinging sunlight than from the electric "engine" lamp.

 

In a different approach: with present electric thrusters, the available power is the limit, more so than the ejected matter. Why should we seek a thruster that saves matter but needs even more power?

 

An even higher ejection speed would be really easy at electric thrusters. Just put a higher voltage, use more charged ions, whatever you want. The difficult part, as opposed, is to consume less power for a given thrust. That's why they use xenon, easy to ionize and heavy, to have more expelled mass per energy spent in ionization. (The other difficult part is for electrodes to work for a long time).

[swansont]

That's why they use xenon, easy to ionize and heavy,

 

 

Heavy, yes. Easy to ionize, not so much.

 

Elements sorted by ionization energy. Scroll down for Xenon. It's near the bottom of the measured elements, 9 from the bottom of ones that have data.

http://www.lenntech.com/periodic-chart-elements/ionization-energy.htm

 

Being a gas is probably part of the reason it's used, too. Decent vapor pressure.

[Enthalpy]

The vapour pressure and the safety together are an obvious advantage of xenon over cesium for instance. Candidate elements are the ones whose gas is monoatomic. N₂ for instance is much more difficult to ionize than N.

 

Ionization is easy with xenon; it results not only from the ionization potential but also from more subtle behaviours. For instance, oxygen can capture lone electrons to quench avalanches efficiently - this reason favours SF₆ as an insulator.