Author Topic: VASIMR Engine  (Read 155205 times)

Offline Stormbringer

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Re: VASIMR Engine
« Reply #100 on: 12/25/2014 07:26 AM »
i got what he said a few posts ago but your illustration is simple and clear. That said...

I think that NASA would tell even an ex astronaut to get bent if they thought he had no plasma separation. they just cannot afford to waste time and space on the ISS for something that they believe will not work. remember in addition to the world's most expensive hourly wages (figuratively) they are paying the astronauts, and consumables for the astronauts and station and premium equipment berthing real estate  the test engine will tap a significant portion of the electrical supply while charging up.

I also do not think Chang Diaz would overlook the plasma separation part of an engine or be unaware of it. Nor do i think he as CEO of his company which has other lucrative irons in  the fire and a rep to maintain if he wants to stay in business; would waste financial support on it if he did not think it would work.

« Last Edit: 12/25/2014 07:32 AM by Stormbringer »
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Offline QuantumG

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Re: VASIMR Engine
« Reply #101 on: 12/25/2014 07:59 AM »
I think that NASA would tell even an ex astronaut to get bent if they thought he had no plasma separation. they just cannot afford to waste time and space on the ISS for something that they believe will not work.

NASA doesn't have an opinion one way or another. That's why it's called an experiment.
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Offline MP99

Re: VASIMR Engine
« Reply #102 on: 12/25/2014 08:31 AM »
Quote
i got what he said a few posts ago but your illustration is simple and clear. That said...

I think that NASA would tell even an ex astronaut to get bent if they thought he had no plasma separation. they just cannot afford to waste time and space on the ISS for something that they believe will not work. remember in addition to the world's most expensive hourly wages (figuratively) they are paying the astronauts, and consumables for the astronauts and station and premium equipment berthing real estate  the test engine will tap a significant portion of the electrical supply while charging up.

I also do not think Chang Diaz would overlook the plasma separation part of an engine or be unaware of it. Nor do i think he as CEO of his company which has other lucrative irons in  the fire and a rep to maintain if he wants to stay in business; would waste financial support on it if he did not think it would work.
The plasma ejects through a magnetic nozzle, but magnetic fields form a loop away and then back.

They need the plasma to be guided by the nozzle in order to transfer momentum to the spacecraft (just like a chemical nozzle), but then detach from the magnetic field instead of following it back again.

They are absolutely aware of this as an issue, it's mentioned in papers, etc. They are convinced that their plasma will detach from their nozzle, but the ISS experiment is the first time that it can actually be demonstrated.

Cheers, Martin
« Last Edit: 12/25/2014 09:02 PM by MP99 »

Offline MP99

Re: VASIMR Engine
« Reply #103 on: 12/25/2014 08:40 AM »
Quote
You would be thinking wrong then. Plasma "poop" is made up of charged particles. If you just shoot out positive ions then a massive electric field will form that will be strong enough to pull those ions back to the rocket, thereby cancelling all thrust. That's why ion thrusters also have electron guns, to neutralize the ions, allowing them to leave the rocket system as neutral atoms.
Vasimr doesn't use such a neutralizing mechanism. In fact, I've never quite understood how the ions were to be neutralized efficiently. That's what will define how well the ions detach and whether their blue glowy stuff has any kick to it.
In an ion drive, the electrons are pulled away from a gas to leave behind ions, which are then accelerated by an electric field. Thus leaves a net charge on the spacecraft unless those stripped-off electrons are then disposed of via the electron gun.

VASIMR heats a neutral gas until some of the electrons separate from their host atoms (form a plasma), but the electrons are left mixed in with the ions, and the plasma overall is electrically neutral. When it is ejected, it carries away equal amounts of positive and negative charge, so no compensation is required.

Cheers, Martin
« Last Edit: 12/25/2014 09:02 PM by MP99 »

Offline Raj2014

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Re: VASIMR Engine
« Reply #104 on: 12/25/2014 11:20 AM »
You say the VASIMR does not produce thrust, yet in the video I posted, we can see the VASIMR move the Momentum/Impulse response target.

Imagine ping pong balls attached to a board by rubber bands.  You make a fancy mechanism that will shoot them out really fast but unless you cut the rubber band they will come back and no net thrust will be produced.  Such a device could move a 'Momentum/Impulse response target' and still be useless in space.  I'm in no position to argue one way or the other but maybe it will help you understand QuantumG's take on the thing.

Thank you for that explanation, also to point out, VASIMR started out in NASA before it went to a private organisation. Also why would NASA approve of the testing on the ISS, if they it does not work. With the testing of VASIMR on ISS, ad astra rocket company are developing battery pack called Aurora, which will store the power needed, turn on VASIMR at 200 kilowatts for about 15 minutes before needing to be recharged. They could add some extra solar panels to the Aurora. 

Offline Nomadd

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Re: VASIMR Engine
« Reply #105 on: 12/25/2014 01:24 PM »
 What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?

Offline Raj2014

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Re: VASIMR Engine
« Reply #106 on: 12/25/2014 01:52 PM »
What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?

From the videos of VASIMR, we can see it apparently does work, which they have tested in a vacuum chamber. They will use it for station boosting and to see how well it will work in a real space environment.

Offline RonM

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Re: VASIMR Engine
« Reply #107 on: 12/25/2014 03:22 PM »
What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?

From the videos of VASIMR, we can see it apparently does work, which they have tested in a vacuum chamber. They will use it for station boosting and to see how well it will work in a real space environment.

As previously mentioned, there probably isn't a vacuum chamber large enough to prove detachment will occur.

The blue glow proves VASIMR produces a plasma. The question is does the plasma continue on to produce a thrust or loops back along the magnetic field and does not produce a thrust. It is possible that the magnetic field will pull the electrons and ions in opposite directions before they recombine as neutral atoms, resulting in no thrust.

Theory says it will work, but they'll have to put it in space to prove it.

Offline Raj2014

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Re: VASIMR Engine
« Reply #108 on: 12/25/2014 03:41 PM »
What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?

From the videos of VASIMR, we can see it apparently does work, which they have tested in a vacuum chamber. They will use it for station boosting and to see how well it will work in a real space environment.

As previously mentioned, there probably isn't a vacuum chamber large enough to prove detachment will occur.

The blue glow proves VASIMR produces a plasma. The question is does the plasma continue on to produce a thrust or loops back along the magnetic field and does not produce a thrust. It is possible that the magnetic field will pull the electrons and ions in opposite directions before they recombine as neutral atoms, resulting in no thrust.

Theory says it will work, but they'll have to put it in space to prove it.


What about NASA's vacuum chamber? I read it is the largest in the world.

Offline Danderman

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Re: VASIMR Engine
« Reply #109 on: 12/25/2014 04:44 PM »
What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?

The same could be asked for any rocket engine.  Why test it in flight if experimental tests on the ground show that the engine works?



Offline Stormbringer

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Re: VASIMR Engine
« Reply #110 on: 12/25/2014 05:07 PM »
i think there is a difference in a system that must get from the surface of the earth to orbit. a fail there means a payload is destroyed at the very least. possibly human passengers. and a whole system has a whole lot more points of failure that the blue glowy poop trying to climb back aboard.
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Offline RonM

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Re: VASIMR Engine
« Reply #111 on: 12/25/2014 06:12 PM »
i think there is a difference in a system that must get from the surface of the earth to orbit. a fail there means a payload is destroyed at the very least. possibly human passengers. and a whole system has a whole lot more points of failure that the blue glowy poop trying to climb back aboard.

No, VASIMR, like any other rocket engine, will have to be tested in flight. That means in space for VASIMR, preferably on ISS. Until it is tested, they can't be sure if it works as intended.

NASA would not design an entire Mars campaign on an engine that might work. They will want to see the data first.

Offline Raj2014

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Re: VASIMR Engine
« Reply #112 on: 12/26/2014 03:25 PM »
Since apparently funding is what stopping them from continuing development of VASIMR, they could start a kickstarter campaign and a petition. I also read that VASIMR could also be used to shield astronauts and spacecraft from radiations, has this been confirmed?

Offline Stormbringer

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Re: VASIMR Engine
« Reply #113 on: 12/26/2014 06:48 PM »
Since apparently funding is what stopping them from continuing development of VASIMR, they could start a kickstarter campaign and a petition. I also read that VASIMR could also be used to shield astronauts and spacecraft from radiations, has this been confirmed?

I have not heard that about VASIMR. I think you have conflated M2P2's intrinsic shielding with VASIMR. VASIMR does not want plasma looping around the ship structure. As QuantumG and others pointed out that would be bad for VASIMR. VASIMR needs the plasma to go away in order to work.

As to crowd funding; Dr Diaz has already ran one such campaign. so he may do another.
« Last Edit: 12/26/2014 07:02 PM by Stormbringer »
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Offline momerathe

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Re: VASIMR Engine
« Reply #114 on: 12/26/2014 09:20 PM »
iterestingly, vasimir may get some experimental support from kickstarter indirectly - a cubesat-sized plasma thruster called CAT: https://www.kickstarter.com/projects/longmier/cat-launch-a-water-propelled-satellite-into-deep-s

as far as I can tell it's a mini-vasimr - if it demonstrates detachment and/or works in orbit, it could provide evidence in support of it's bigger brother.
thermodynamics will get you in the end

Online MickQ

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Re: VASIMR Engine
« Reply #115 on: 12/28/2014 12:37 AM »
Maybe a VASIMR test unit and an Aurora battery on a demonstrator flown as a secondary payload on a Falcon 9 or Antares ?

Mick.

Offline cordwainer

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Re: VASIMR Engine
« Reply #116 on: 12/28/2014 03:30 AM »
Chemical rockets on the correct trajectory and launch windows or longer flight times with better shielding would work for manned missions to Mars just fine. Zubrin is correct in that the advantage of VASIMR is for unmanned cycler orbits to Mars of probes and supplies for colonists. Hi-PEP along with other technologies would be a better option for ISS and orbital ACS/RCS. The variable thrust that VASIMR technology provides would be much more suited to long and efficient cycler flights than ACS.

Offline savuporo

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Re: VASIMR Engine
« Reply #117 on: 12/28/2014 05:40 AM »
VASIMR or this ? http://arc.aiaa.org/doi/abs/10.2514/1.B35250 ( published 2014 )


We had a thread on this, there is a previous publication and some previous coverage too

http://www.nasa.gov/centers/langley/news/researchernews/rn_ColloquiumWinterberg.html


EDIT: while i was trawling AIAA of 2014 anyway, i came across VASIMR paper ( of course ) too , here
http://arc.aiaa.org/doi/abs/10.2514/6.2014-4173
Full version : http://www.adastrarocket.com/Jared-Space2014.pdf

Quote
Detailed mapping of the plasma plume has been accomplished at a power level of 100 kW in a volume extending more than 2 m  downstream of the exhaust exit, without significant neutral background interaction. This has led to a compelling demonstration of how the plasma effectively flows away from the magnetic nozzle of a VASIMR« type device.(4)

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6823704
Quote
Understanding the physics involved in plasma detachment from magnetic nozzles is well theorized, but lacking in large scale experimental support. We have undertaken an experiment using the 150-m│ variable specific impulse magnetoplasma rocket test facility and VX-200 thruster seeking evidence that detachment occurs and an understanding of the physical processes involved. It was found that the plasma jet in this experiment does indeed detach from the applied magnetic nozzle (peak field ~2 T) in a two part process

I am not a plasma scientist, but IEEE and AIAA have accepted these publications.

My favorite AIAA links this year :
http://arc.aiaa.org/doi/book/10.2514/MSPOPS14 ( all free PDF access )
http://arc.aiaa.org/doi/book/10.2514/MSPACE14
« Last Edit: 12/28/2014 06:08 AM by savuporo »
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Offline QuantumG

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Re: VASIMR Engine
« Reply #118 on: 12/28/2014 05:59 AM »
Cancel the ISS experiment then, clearly it's not necessary. That's what Ad Astra are saying, right?
I hear those things are awfully loud. It glides as softly as a cloud. What's it called? Monowhale!

Offline savuporo

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Re: VASIMR Engine
« Reply #119 on: 12/28/2014 06:20 AM »
Cancel the ISS experiment then, clearly it's not necessary. That's what Ad Astra are saying, right?

Huh ? ISS demo is sort of required to get it out of the TRL valley of death, otherwise it has no hopes of leaving earth orbit ever.
ISS happens to be the only suitable idea with sufficient power generation available for a meaningful TRL 7ish demo.
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