Community > Forum > Technology & Science > VASIMIR

VASIMIR

Posted by: Andy Hill - Fri Jul 10, 2009 9:35 am
Post new topic Reply to topic
 [ 64 posts ] 
Go to page 1, 2, 3, 4, 5  Next
VASIMIR 
Author Message
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post VASIMIR   Posted on: Fri Jul 10, 2009 9:35 am
This recent article talks about testing of the new VASIMIR engine.

http://www.aviationweek.com/aw/generic/ ... t%20Levels

It talks about power levels required of upto 200kW, this seems much larger than we can currently produce very easily and I'm not sure how much thrust this would produce. Such an engine is very efficient but I dont see how it is likely to provide enough thrust to propel a structure large enough to service the power requirement necessary for a manned craft.

Anyone got any figures for thrust verses power input.

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Moon Mission Member
Moon Mission Member
User avatar
Joined: Tue Jul 15, 2003 8:46 pm
Posts: 1215
Location: Kapellen, Antwerp, Belgium, Europe, Planet Earth, the Milky Way Galaxy
Post Re: VASIMIR   Posted on: Fri Jul 10, 2009 9:40 am
You can read this http://spacefellowship.com/2009/07/06/v ... ull-power/ and a lot more news on this website's news section: http://spacefellowship.com/

Our article has a lot more information, maybe your answer is in there somewhere.

_________________
Heavier-than-air flying machines are impossible. - Lord Kelvin, 1892


Back to top
Profile WWW
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post Re: VASIMIR   Posted on: Sat Jul 11, 2009 10:05 am
Sorry Sigurd couldn't find what I was looking for in the fellowship article either, I did find out a bit more on wikipedia though.

http://en.wikipedia.org/wiki/Vasimir

here's a interesting piece of information from the above wikipedia entry:

Quote:
The ISS VASIMR engine will operate in burst mode. Since ISS's power generation is not great enough, the system will include a trickle-charged battery system allowing for 10 min pulses of thrust. This however, is expected to be sufficient to maintain ISS altitude, eliminating the need for costly, periodic chemical rocket reboosting operations.


Obviously fuel for the VASIMIR will need to be brought up but that is going to be a lot less than is currently needed. I'm surprised that the 5N of thrust the article talks about is enough to stop the ISS orbit from degrading.

There is also a bit about a space tug operating between LEO and the moon. This all seems very hopeful but these systems are very power hungry so I suspect either much more efficient solar cells of possibly a small nuclear power pack will be eeded to take full advantage of it.

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Space Station Commander
Space Station Commander
User avatar
Joined: Mon Oct 06, 2003 9:22 pm
Posts: 843
Location: New York, NY
Post Re: VASIMIR   Posted on: Sat Jul 11, 2009 8:23 pm
atmospheric drag even at altitudes as low as 200km provides a very very small amount of actual thrust, it's just an issue because it's always there and will de-orbit an object over time. 5N is an actually macroscopic amount of force and will easily be able to counteract the effects of drag. you can calculate the drag force fairly easily, and i promise it'll be on the order of 10^-5N or less (probably under 10^-6) even for something the size of the ISS.

_________________
Cornell 2010- Applied and Engineering Physics

Software Developer

Also, check out my fractals


Back to top
Profile
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post Re: VASIMIR   Posted on: Mon Jul 13, 2009 10:16 am
I wonder whether it might be possible to use Hydrogen as fuel for the VASIMIR, currently the ISS dumps Hydrogen as a waste product of oxygen production.

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Space Station Commander
Space Station Commander
User avatar
Joined: Mon Oct 06, 2003 9:22 pm
Posts: 843
Location: New York, NY
Post Re: VASIMIR   Posted on: Mon Jul 13, 2009 4:29 pm
you can use any element to fuel vasimr as far as i'm aware, but hydrogen would be a very bad choice in all likelihood because it's so light. i could be wrong on that, it is easy to ionize, but something heavier like argon is definitely better. i doubt the mass benefit of not using argon (really not a big concern, they need extra batteries and stuff even to run the damn thing) is worth it.

_________________
Cornell 2010- Applied and Engineering Physics

Software Developer

Also, check out my fractals


Back to top
Profile
Space Station Commander
Space Station Commander
User avatar
Joined: Mon May 31, 2004 9:47 pm
Posts: 812
Location: Yerushalayim (Jerusalem) - capital of Israel!
Post Re: VASIMIR   Posted on: Mon Aug 31, 2009 12:52 pm
If you can use any element, why not uranium? That has like, tons of mass for the volume. It even radiates by itself . . .

_________________
“Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.”
-Anonymous


Back to top
Profile WWW
Spaceflight Trainee
Spaceflight Trainee
User avatar
Joined: Tue Jun 15, 2004 10:26 am
Posts: 44
Location: Switzerland
Post Re: VASIMIR   Posted on: Tue Sep 01, 2009 10:45 pm
Hydrogen is actually quite a good choice for such a plasma thruster. Due to its low mass it leaves the thruster at a high velocity, leading to a high specific impulse (i.e. an efficient use of fuel). Sure, you need a large volume and hence a large tank, but pound-for-pound it gives you the largest delta-v. One way to see this is that in most thrusters, the flow velocity at the exit/throat (hence the specific impulse) will be approx. the sound speed. This scales as ~SQRT(T/M), with T the temperature and M the ion mass. So, the larger the mass, the smaller the specific impulse. (in a magnetic nozzle such as in VASIMR, this might work somewhat differently, but this is the basic idea). One of the challenges of using hydrogen is that it suffers from large volume recombination losses (i.e. ions and electrons find each other fast), due to it being a molecular gas.

The thrust depends largely on the mass flow rate, so that will indeed probably be lower when using hydrogen. However, one of the main advantages of the VASIMR system is that you can - given a total available power - tune it to high thrust or high specific impulse. This probably allows you to run in a mode with still relatively high thrust using hydrogen.

Regarding using different feed gasses: in principle you can indeed ionize and accelerate in this way all gasses (note the word gasses). However, the helicon antenna and the accompanying power supplies that Ad Astra uses are typically tuned to a certain plasma (i.e. gas feed). Take for example the "second stage" ICRH heating in the VASIMR. ICRH stands for Ion Cyclotron Resonance Heating. The name gives away some of the challenges you encounter when trying such things. First of all, you have to hit a certain narrow resonance (by tuning the frequency of the RF power supply). This frequency is the ion cyclotron frequency, which depends on the mass of the ions (and the magnetic field). I don't know the flexibility of Ad Astra's system, but I can image that if you use a very different mass particle, the right frequency can probably not be tuned in with your power supply or effectively coupled into the plasma with the antenna you have. High power RF power supplies that can be tuned over a large frequency range are typically also very expensive. We have a tunable RF power supply in our lab that has an output that is a tiny fraction of the 200 kW that the VX-200 needs and that is already 100k Euro. I think we have another one that is not so tunable with an output power of ~2 kW that is of the same order. So, don't take this lightly. The solid-state power supplies that Ad Astra had ordered turned out to be quite difficult to make (if I read the website correctly) and have delayed the testing schedule by quite a few months. They have been delivered, AFAIK.

To my knowledge (it's been a while since I checked), all their tests of their new VX-200 thruster have been performed with argon.

This, of course, is all very much simplified... ;) Hope I have made this somewhat clearer.

_________________
For every complex problem there is a solution that is clear, simple, and wrong. - Henry Louis Mencken


Back to top
Profile
Space Station Member
Space Station Member
User avatar
Joined: Mon Feb 25, 2008 9:51 am
Posts: 443
Location: Vienna, Austria, Europe, Earth
Post Re: VASIMIR   Posted on: Thu Sep 03, 2009 11:01 am
IF the VX-200 prototype is successful, then the "ISS-VASIMR" will be designed to use the waste-hydrogen from the station.
Quote:
The prototype would draw its electrical power from the Station's solar panels. If the test were successful, the VASIMR prototype could be moved to a different part of the Station and used to help keep it in orbit. While ISS orbits the Earth, atmospheric drag gradually pulls it closer to the Earth. Every so often, the Station has to be boosted back into a higher orbit. This is done by a variety of means, but all of them require fuel launched into orbit from Earth. The VASIMR engine, however, could change that, since it would use hydrogen, which is already generated as a waste product on the Station. By using waste hydrogen and electricity from the Station's solar panels, VASIMR could maintain the ISS's orbit without requiring any additional fuel.

Source: http://www.nasa.gov/vision/space/travel ... lsion.html

_________________
pride comes before a fall


Back to top
Profile
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post Re: VASIMIR   Posted on: Thu Sep 03, 2009 5:02 pm
Marcus Zottl wrote:
IF the VX-200 prototype is successful, then the "ISS-VASIMR" will be designed to use the waste-hydrogen from the station.


Is this the point where I claim that this was my idea all along and that NASA has stolen it from my previous post and I should be given all the credit? :D

Well I'll be gracious as long as they put my name in 1 metre high letters on the side of the ISS I'll keep quite about the whole thing. :D

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Spaceflight Trainee
Spaceflight Trainee
User avatar
Joined: Thu Sep 03, 2009 7:41 pm
Posts: 46
Post Re: VASIMIR   Posted on: Thu Sep 03, 2009 9:38 pm
Hope they get that up soon.


Back to top
Profile
Space Station Commander
Space Station Commander
User avatar
Joined: Mon May 31, 2004 9:47 pm
Posts: 812
Location: Yerushalayim (Jerusalem) - capital of Israel!
Post Re: VASIMIR   Posted on: Fri Sep 04, 2009 9:03 am
There are other byproducts in the station. For example, methane . . . I assume that even astronauts have gas . . . :D

_________________
“Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.”
-Anonymous


Back to top
Profile WWW
Space Station Member
Space Station Member
User avatar
Joined: Mon Feb 25, 2008 9:51 am
Posts: 443
Location: Vienna, Austria, Europe, Earth
Post Re: VASIMIR   Posted on: Fri Sep 04, 2009 9:24 am
Andy Hill wrote:
Marcus Zottl wrote:
IF the VX-200 prototype is successful, then the "ISS-VASIMR" will be designed to use the waste-hydrogen from the station.


Is this the point where I claim that this was my idea all along and that NASA has stolen it from my previous post and I should be given all the credit? :D


Well, not exactly. If you take another look at the link that I provided, you may notice that that particular page is from way back in 2003 ;)

_________________
pride comes before a fall


Back to top
Profile
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post Re: VASIMIR   Posted on: Fri Sep 04, 2009 3:48 pm
Marcus Zottl wrote:
Andy Hill wrote:
Marcus Zottl wrote:
IF the VX-200 prototype is successful, then the "ISS-VASIMR" will be designed to use the waste-hydrogen from the station.


Is this the point where I claim that this was my idea all along and that NASA has stolen it from my previous post and I should be given all the credit? :D


Well, not exactly. If you take another look at the link that I provided, you may notice that that particular page is from way back in 2003 ;)


Damn, foiled again. :)

What do you think, any point in keep harping on about it anyway and claiming credit? :)

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Space Station Member
Space Station Member
User avatar
Joined: Mon Feb 25, 2008 9:51 am
Posts: 443
Location: Vienna, Austria, Europe, Earth
Post Re: VASIMIR   Posted on: Mon Sep 07, 2009 9:30 am
Maybe you could get one of the admins to change the date of your post to something before 2003? ;) :mrgreen:

_________________
pride comes before a fall


Back to top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 64 posts ] 
Go to page 1, 2, 3, 4, 5  Next
 

Who is online 

Users browsing this forum: No registered users and 26 guests


© 2014 The International Space Fellowship, developed by Gabitasoft Interactive. All Rights Reserved.  Privacy Policy | Terms of Use