Ion Drive Question - Ionization process

[Halzman]

I'm fairly familiar with the design and operation of an ion engine, although I do have a two questions in regard to its operation.

1) Normally, an ion engine would be used in space (which is naturally a vacuum) and would output its given thrust. Prior to space flight, is there a need to maintain the vacuum within the chamber where the ionization occurs?

2) When looking at the ion optics, we see that there is 2 perferated sheets, with holes .1 mm range (if i remember correctly) on each sheet. I'm assuming that this would be enough to cause a 'leak' in the chamber, if it was a vacuum to begin with. Does the chamber need to be a vacuum in order for the ionization to occur? If yes, what is the highest pressure density that the chamber can be in order for ionization to occur? I guess more specifically my question is, can an ion engine function in a non vacuum environment? (obviously there would be a problem with weight to thrust, but I'm not concerened with that)

I'm aware that NASA (it could of been the ESA) uses a vacuum chamber to test the ion engine. I'm just curious if it would function in a normal atmospheric pressure environment, and if not, could you balance it out by maintaining a certain vacuum within the chamber.

Just thought of a 3rd question: Would an ion drive work under water?

 

[Astronuc]

The greater the density of gas in the ion engine, the higher the current/energy necessary to produce ions, and just ions. The density needs to be reduced to optimize the number of ions as opposed to neutral atoms. Otherwise, one simply ends up with a discharge in a gas.

The aspect is that the thrust is so low that it simply would not work in an atmosphere.

An ion engine like the gas engine described would not work underwater.

One might wish to use an MHD engine instead.

 

[Halzman]

The greater the density of gas in the ion engine, the higher the current/energy necessary to produce ions, and just ions. The density needs to be reduced to optimize the number of ions as opposed to neutral atoms. Otherwise, one simply ends up with a discharge in a gas.

The aspect is that the thrust is so low that it simply would not work in an atmosphere.

An ion engine like the gas engine described would not work underwater.

One might wish to use an MHD engine instead.

Pretty much expected it not to work in a regular atmosphere/underwater. Just had to ask. However, couldn't the thrust be improved by pumping more power? I know currently were not capable of supply effecient amounts of power to an ion drive (one that's space bound atleast) but is that 1 of the most limiting factors when it comes to thrust?

 

[Astronuc]

Pretty much expected it not to work in a regular atmosphere/underwater. Just had to ask. However, couldn't the thrust be improved by pumping more power? I know currently were not capable of supply effecient amounts of power to an ion drive (one that's space bound atleast) but is that 1 of the most limiting factors when it comes to thrust?

The accelerating potential is the limiting aspect.


You may wish to investigate the DS4G thruster technology

http://prl.anu.edu.au/SP3/research/SAFEandDS4G

http://www.esa.int/gsp/ACT/propulsion/safe_thruster.htm

http://www.esa.int/esaCP/SEMOSTG23IE_Expanding_0.html

http://www.abc.net.au/ra/innovations/stories/s1579297.htm

 

[Halzman]

The accelerating potential is the limiting aspect.

You may wish to investigate the DS4G thruster technology

http://prl.anu.edu.au/SP3/research/SAFEandDS4G

http://www.esa.int/gsp/ACT/propulsion/safe_thruster.htm

http://www.esa.int/esaCP/SEMOSTG23IE_Expanding_0.html

http://www.abc.net.au/ra/innovations/stories/s1579297.htm

Thanks, I actually became aware of the new type of ion drive a few days ago. Looks very promising and interesting. I've been interested in building and testing my own ion drive. I have a solid design for the drive itself, as well as all the components. Whether the chamber needs to be a vacuum was the only main question I had. I was aware of the grid errosion problem, so to here about ESA's DS4G was almost a 'breakthrough' on my end. I had always intended to use xenon, as NASA did on DSP.

 

[koondaddy]

thinking outside the box

keep in mind the new ion engine advances, and the DARPA WALRUS program which may use atmospheric ion propulsion. I want to spin a 56' rotor to a tip speed of 210 MPH using 5 small ion thrusters. Is this possible?