VASIMR Plasma Thruster: Questions Answered

[AlkamlBan]

First off, I want to apologize if this thread is in the wrong place but I am new this. Anyway, so I recently checked on the VASIMR plasma engine since I was interested in it. But one thing I didn't understand about it is if it ejects the neutral gas it uses. What I mean is that it obviously needs a neutral gas to work but does it eject it out of the thruster or can it be used "infinitely" (I mean for a long time not literally). In the case where it does eject it out the back is it possible for air to be inserted, have the neutral gases secluded and then use them for continuing the thrust?

 

[NascentOxygen]

Hi AlkamalBan.

The gas is turned into the plasma propellant. Even if you could substitute air, from where would you source that supply of air?

http://www.industrytap.com/nasas-new-vasimr-plasma-engine-reach-mars-39-days/33646

 

[AlkamlBan]

Interesting, I was considering its capabilities for flight on Earth where it could have an air intake but I am not so sure if the heat for the plasma coming out the back would burn things or not.

 

[mfb]

Compared to more conventional propulsion methods it would be horribly inefficient in an atmosphere. It also requires too much power to be of practical use within the timescales of atmospheric flight.

 

[NascentOxygen]

It's basically a very low power electric rocket motor, its energy comes from the battery (chemical or nuclear, or solar cells). The propellant is not a fuel so is not a source of energy. The motor is not for use on Earth.

 

[AlkamlBan]

Compared to more conventional propulsion methods it would be horribly inefficient in an atmosphere. It also requires too much power to be of practical use within the timescales of atmospheric flight.

Ok got that, but one last thing I want to know is if the plasma coming out the back is hot enough to burn something at a distance or is it safe (aka hot but only at a small distance from the thruster?

 

[mfb]

It is very hot, but it has a low density. The effect will depend on what you do and how the environment looks like.