Author Topic: VASIMR Engine  (Read 156252 times)

Offline Hop_David

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Re: VASIMR Engine
« Reply #280 on: 05/08/2015 02:59 AM »
OTOH, I believe your 0.7 km/s from EML through TMI is low - you'll use about half that just leaving EML (the perigee lowering burn as you pass the Moon), so you can do an Oberth burn at earth. But the Oberth burn itself can be around 1 km/s (or some of the numbers appropriate for cargo mission do seem to be lower, as per your estimate).

.15 km/s suffices to drop from EML2 to a 111 km altitude perilune. At perilune it's traveling near lunar escape and so enjoys an Oberth benefit. A .18 km/s perilune burn will drop the ship to a deep perigee.

At perigee the ship is traveling 10.8 km/s. Hyperbolic velocity for Trans Mars Insertion is 11.3 km/s. So a .5 km/s perigee burn sends the ship on its way to Mars.

.15 + .18 + .5 = .83. From EML2 to TMI is about .8 km/s.

Offline Impaler

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Re: VASIMR Engine
« Reply #281 on: 05/09/2015 05:34 AM »

You're easily amused.

Yes, I don't need to go through the trouble of resurrecting some point from months ago for my kicks.

It's a flat plateau after you reach C3=0? Um, no. Your Grand Canyon metaphor is way off base. Once you reach reach the edge of earth's Hill Sphere you still need another 3 km/s to raise your aphelion to 1.52 A.U.

It should have been obvious that slope in the canyon analogy referred to the gravity well of Earth and the need for high thrust to make use of the Oberth effect inside that well, not the DeltaV which was expressed as actual accelerating the car.  I made it quite clear that their was more acceleration to be done beyond C3=0, what's off base is your mangling of the analogy.

Your correct that we can just depart from EML1 directly to Earth Escape without doing any swing buys of the moon or Earth.  And the DeltaV is VIRTUALLY THE SAME.  The Chemical high thrust system gets a LITTLE boost of something like 100 m/s from plunging deep into thouse gravity wells and burning with an Oberth effect.

Wrong.

Falling from a high apogee you'd be moving 10.8 km/s at perigee.

At that speed, a .5 km/s burn will give you 3 km/s Vinfinity.



You've simply repeated your figures from several months prior, I didn't directly reply because the discussion rapidly moved into your challenge of how a SEP vehicle could be powered, which I answered forthwith.  While I did badly underestimate the Oberth effect the overall mission architecture of kick-stages for SEP vehicles is still not compelling.

The ratio of burn to Vinfinity is 6 and assuming best case Hydrolox ISP of 450 we could replace all the propellent expended in the .5 km/s burn (or any amount burned at perigee) 1:1 with SEP propellents operating at 2700s ISP.  All the mass of that kick stages engine, along wither all the propellent retained for the kick stage reuse is just a dead-weight loss.  And 3000s is really the low end of what any likely SEP vehicle is going to do, 5000s is more likely to what your competing with.

.4 km/s to drop from EML2 and a .5 km/s perigee burn for TMI. The delta V from EML2 to TMI is only .9 km/s. So the booster stage can be a lot smaller than the MTV. Accordingly I ditched your Hummer for the more appropriate Moped.

After separation it will take the Moped another .9 km/s to get back to EML2 but this will take a lot less propellent since the Moped has much less dry mass. With an .18 km/s delta V budget and no need to endure an 8 km/s atmospheric re-entry, the Moped's reuse becomes a little more plausible.

In the mean time the MTV is on its way to mars without the mass of the moped.

If a one km/s acceleration takes 11 days, that LITTLE boost saves 33 days.

First off you yourself said the drop from EML2 to Earth perigee took 9 days so the saving would be 21 days not 33.  Our trip to Mars using SEP is months (cause fast trips are wasteful even if we had amazing alpha) so were hardly changing the length of the journey, in fact many low thrust Mars transfers cut the engine off during the middle phase of the journey so we may end up with no savings at all.

Kick stages for SEP are like very large carrier aircraft for launch vehicles.  Technically they squeeze a bit of performance out of the thing they are assisting, but it's not remotely worth the cost and complexity.  Like the old Elon quote "just make the rocket 10% bigger" and you have completely replaced the whole system of multiple vehicles, multiple propellents, multiple docking and in-situ propellents collected at tremendous cost.  I know your 'gung-ho' for lunar/asteroid derived propellents but your proposal is just trying to shoe-horn them into places they aren't useful.  If your not showing clear order-of-magnitude reduction in launch masses then forget about in-situ propellents, the production costs and infrastructure will eat up anything less then that.

Once Electric propulsion came on the scene it basically made chemical engines for in-space use obsolete and all the H2O molecules in asteroids and comets got rendered obsolete at the same time.  We can do so much better with the heavy noble gasses as propellents that we would only be interested in standard fuel/oxidizer bi-propellents when we are on a planetary surface such as the classic hydrocarbon production on Mars concept (which DOSE show a clear order of magnitude reduction in launch mass).

The only way things like water are going to be good in-space propellents again is if we get Electric thrusters that can utilize them.  This is a definite possibility, HALL thrusters can operate on a mixture of light elements so long as they have some heavy noble gasses to catalyze the ionization process, but they take an efficiency hit from higher ionization energy needs.  The most promising concept is the Electrode-less Lorentz Force thruster (ELF) which might be able to inject un-ionized gas into it's exhaust and hugely reduce the parasitic loss of ionization which would make the light elements far more attractive.  If such things can be developed then comet and asteroid 'bag and bake' methodologies may prove viable.
« Last Edit: 05/09/2015 06:28 AM by Impaler »

Offline dkovacic

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Re: VASIMR Engine
« Reply #282 on: 05/28/2015 11:57 AM »
Very interesting progress update on ISDC 2015, presented by Dr. Franklin Chang Diaz



Highlights:
1. Ions and electrons in the same plume, no neutralization needed
2. Primarily using argon, 6N thrust level achieved (estimated isp 3000s)
3. More than 10000 firings of VX-200
4. 70% efficiency with argon and ISP of 5000s.
5. With krypton, they could reach 75% efficiency.
6. CDR milestone beginning 2016.
7. ISS flight milestone beginning of 2018.
8. ISS reboost currently requires 7t of fuel and 210 million USD per year
9. Smaller 80kW unit would require 1/10 of this cost
10. various application specific animations shown

Offline Raj2014

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Re: VASIMR Engine
« Reply #283 on: 05/28/2015 12:51 PM »
Very interesting progress update on ISDC 2015, presented by Dr. Franklin Chang Diaz



Highlights:
1. Ions and electrons in the same plume, no neutralization needed
2. Primarily using argon, 6N thrust level achieved (estimated isp 3000s)
3. More than 10000 firings of VX-200
4. 70% efficiency with argon and ISP of 5000s.
5. With krypton, they could reach 75% efficiency.
6. CDR milestone beginning 2016.
7. ISS flight milestone beginning of 2018.
8. ISS reboost currently requires 7t of fuel and 210 million USD per year
9. Smaller 80kW unit would require 1/10 of this cost
10. various application specific animations shown

I was just now going to post the link to that video. Comparing VX-200 to other electric propulsions for example hall effect thruster, VASIMR is looking good. I read that NASA is going to use hall effect thrusters for the ARM mission.  VASIMR will be also a good choice to use.

Offline dkovacic

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Re: VASIMR Engine
« Reply #284 on: 05/29/2015 09:33 AM »

I was just now going to post the link to that video. Comparing VX-200 to other electric propulsions for example hall effect thruster, VASIMR is looking good. I read that NASA is going to use hall effect thrusters for the ARM mission.  VASIMR will be also a good choice to use.

VASIMR is still TRL6, and it will not be TRL9 until 2018, so that is a probable reason why it is not considered. Besides, Hall thrusters have much more actual flight heritage. But the main reason is that for ARM you don't really need variable ISP so much.

In my opinion, 70% efficiency is the real breakthrough, because it simplifies cooling requirements. I would expect that most of the losses are dissipated as heat inside the engine which has to be removed somehow. As far as I know, VASIMR has the highest thrust among electric propulsion devices produced so far.

Offline Nilof

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Re: VASIMR Engine
« Reply #285 on: 05/29/2015 02:52 PM »

I was just now going to post the link to that video. Comparing VX-200 to other electric propulsions for example hall effect thruster, VASIMR is looking good. I read that NASA is going to use hall effect thrusters for the ARM mission.  VASIMR will be also a good choice to use.

VASIMR is still TRL6, and it will not be TRL9 until 2018, so that is a probable reason why it is not considered. Besides, Hall thrusters have much more actual flight heritage. But the main reason is that for ARM you don't really need variable ISP so much.

In my opinion, 70% efficiency is the real breakthrough, because it simplifies cooling requirements. I would expect that most of the losses are dissipated as heat inside the engine which has to be removed somehow. As far as I know, VASIMR has the highest thrust among electric propulsion devices produced so far.

Well, OTOH the X-3 nested hall thruster was tested at about 2 N of thrust in 2013-2014, and was planning to double that "soon" roughly a year ago. I don't know about any SEP engine with a noticeably higher test stand thrust than the VX-200 though.

The possibility of using Krypton on Vasimr for better performance (and denser storage with a higher mass ratio) is also great news, and makes comparing different engines easier.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Impaler

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Re: VASIMR Engine
« Reply #286 on: 05/29/2015 05:57 PM »
VASIMR dose not compare favorably with the X3 HALL thruster, it has a much lower thrust:weight ratio

Offline Nilof

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Re: VASIMR Engine
« Reply #287 on: 05/29/2015 07:41 PM »
Well, since the efficiency numbers have gone up, thrust per weight for a given Isp may have gone up as well. I'd be interested to see some updated numbers on VASIMR's thrust to weight ratio. In previous comparisons it was heavier than some other systems, but it certainly still has the performance needed to be used in something similar to the COMPASS spacecraft. Looking beyond mass, it is certainly bulkier than Halls though.

With that said, in the long run everything will eventually be obsolete. Ad astra currently has the advantage of having the largest single thruster that can fly within a short timeframe. With the latest numbers, it also seems to have a noticeably higher efficiency than Halls which is great in the current situation of power-limited spacecraft.

While it might not keep the advantages it has for long and should already be outmatched in T/W by other systems, it may be rather useful over the next decade, especially for unmanned missions going farther out than Mars.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Raj2014

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Re: VASIMR Engine
« Reply #288 on: 05/30/2015 10:56 PM »
After the VX-200 SS, in the power point is it showing in the video a diagram, will Ad Astra make the VF-200 1 still for the ISS at a later date?
« Last Edit: 05/30/2015 10:57 PM by Raj2014 »

Offline Raj2014

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Re: VASIMR Engine
« Reply #289 on: 07/18/2015 10:35 PM »

I was just now going to post the link to that video. Comparing VX-200 to other electric propulsions for example hall effect thruster, VASIMR is looking good. I read that NASA is going to use hall effect thrusters for the ARM mission.  VASIMR will be also a good choice to use.

VASIMR is still TRL6, and it will not be TRL9 until 2018, so that is a probable reason why it is not considered. Besides, Hall thrusters have much more actual flight heritage. But the main reason is that for ARM you don't really need variable ISP so much.

In my opinion, 70% efficiency is the real breakthrough, because it simplifies cooling requirements. I would expect that most of the losses are dissipated as heat inside the engine which has to be removed somehow. As far as I know, VASIMR has the highest thrust among electric propulsion devices produced so far.

Here is an update on VASIMR. You will need to translate it if you can not read Spanish.
« Last Edit: 07/18/2015 10:35 PM by Raj2014 »

Offline MP99

Re: VASIMR Engine
« Reply #290 on: 07/20/2015 06:53 AM »


OTOH, I believe your 0.7 km/s from EML through TMI is low - you'll use about half that just leaving EML (the perigee lowering burn as you pass the Moon), so you can do an Oberth burn at earth. But the Oberth burn itself can be around 1 km/s (or some of the numbers appropriate for cargo mission do seem to be lower, as per your estimate).

.15 km/s suffices to drop from EML2 to a 111 km altitude perilune. At perilune it's traveling near lunar escape and so enjoys an Oberth benefit. A .18 km/s perilune burn will drop the ship to a deep perigee.

At perigee the ship is traveling 10.8 km/s. Hyperbolic velocity for Trans Mars Insertion is 11.3 km/s. So a .5 km/s perigee burn sends the ship on its way to Mars.

.15 + .18 + .5 = .83. From EML2 to TMI is about .8 km/s.

I'm late to the party here, but thanks for the corrections. (Looks like I'd mis-remembered the ~1 km/s as the Earth perigee burn, instead of the total dV budget.)

Cheers, Martin

Offline manboy

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Re: VASIMR Engine
« Reply #291 on: 07/20/2015 07:32 AM »
Here is an update on VASIMR. You will need to translate it if you can not read Spanish.
In March they got $10 mill from NASA. They plan to test the engine for a continuous 100 hours. May be ready to fly in late 2017. The International Space Station is mentioned by I'm unsure if VASIMR is still planned to be tested there.
« Last Edit: 07/20/2015 07:32 AM by manboy »
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Online A_M_Swallow

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Re: VASIMR Engine
« Reply #292 on: 07/20/2015 01:39 PM »
Is there an existing bus and guidance system that the VASIMR can use as a payload?

Solar panels will also be needed. 200 kW for a continuous burn or by trickle charging the battery pack in 15 minute bursts.

Offline Raj2014

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Re: VASIMR Engine
« Reply #293 on: 07/20/2015 04:09 PM »
Here is an update on VASIMR. You will need to translate it if you can not read Spanish.
In March they got $10 mill from NASA. They plan to test the engine for a continuous 100 hours. May be ready to fly in late 2017. The International Space Station is mentioned by I'm unsure if VASIMR is still planned to be tested there.

Yes I know. Thank you for telling me the information I already know. The link I posted was written on the 7th July and the test started on the 1st July. As for the ISS VASIMR, apparently it has been cancelled. 

Online docmordrid

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Re: VASIMR Engine
« Reply #294 on: 08/12/2015 09:42 AM »
Quote
Ad Astra Rocket Company and NASA move to execution phase of NextSTEP VASIMR partnership

Press Release From: Ad Astra Rocket Company

Posted: Monday, August 10, 2015

Ad Astra Rocket Company and NASA have successfully completed contract negotiations on the company's Next Space Technology Exploration Partnerships (NextSTEP) award, announced on March 31, 2015, and now enter the execution phase of the project.

The parties executed the contract, a three-year, fixed price agreement, on August 7, 2015 for a total value of just over $9 million. The agreement is structured as a one-year contract with two additional one-year extensions based on the accomplishment of mutually agreed upon progress milestones.

NASA's Advanced Exploration Systems Program sponsors NextSTEP awards in a 50/50 cost partnership with industry. Under this award, Ad Astra will conduct a long duration, high power test of an upgraded version of the VX-200TM VASIMR prototype, the VX-200SSTM (for steady state), for a minimum of 100 hours continuously at a power level of 100 kW. These experiments aim to demonstrate the engine's new proprietary core design and thermal control subsystem and to better estimate component lifetime. The tests will be conducted in Ad Astra's large, state-of-the-art vacuum chamber in the company's Texas facility.

Since its inception in 2005, Ad Astra has continued to advance the technology readiness level (TRL) of the VASIMR engine almost exclusively with private funding. This funding enabled the company to complete more than 10,000 successful high power firings, demonstrating the engine's excellent reliability and performance (6 N thrust, 5000 sec Isp at greater than 70% efficiency) with no measurable signs of engine wear.
To optimize company resources, these tests were of short duration (less than 1 minute), but sufficiently long to reliably establish the rocket's performance and measure thermal loads. Now, a longer duration test is needed to validate the new rocket core design for extended operation in space. Going forward in partnership with NASA under the NextSTEP award, Ad Astra continues the technology maturation of the VASIMR to a TRL level greater than 5, a step closer to flight.

"We are proud of our accomplishments and thrilled by this announcement, which gives us a big boost toward space," said Dr. Mark D. Carter, Ad Astra's Sr. VP, Technology Development. "I am proud to be a be part of this project, an example of a progressive commercial-NASA partnership, seeking to advance the United States' electric propulsion capability for the future of spaceflight," said Dr. Jared P. Squire, Ad Astra's Sr. VP, Research. Drs. Carter and Squire are leading the project at Ad Astra as Principal and Co-Principal Investigators respectively.

ABOUT THE TECHNOLOGY

Short for Variable Specific Impulse Magnetoplasma Rocket, VASIMR works with plasma, an electrically charged gas that can be heated to extreme temperatures by radio waves and controlled and guided by strong magnetic fields. The magnetic field also insulates nearby structures so exhaust temperatures well beyond the melting point of materials can be achieved. In rocket propulsion, the higher the temperature of the exhaust gases, the higher their velocity and the higher the fuel efficiency. Plasma rockets feature exhaust velocities far above those achievable by their chemical cousins, so their fuel consumption is extremely low.
DM

Online A_M_Swallow

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Re: VASIMR Engine
« Reply #295 on: 08/12/2015 01:48 PM »
Does NASA have a use for the VASIMR in mind?
Or is this a general research project?

Offline Raj2014

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Re: VASIMR Engine
« Reply #296 on: 08/12/2015 03:32 PM »
Does NASA have a use for the VASIMR in mind?
Or is this a general research project?

Either way it is good news for VASIMR. I hope they do have a use for VASIMR if not I am sure many people could find uses for it. I can think of some right now.

Offline kdhilliard

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Re: VASIMR Engine
« Reply #297 on: 08/14/2015 10:30 PM »
It's no secret that Robert Zubrin has a beef with Chang Díaz and VASIMR, but I was amused that he would take the opportunity to get another jab in while introducing the MIT students vs. Mars One debate last night at the Mars Society Convention.

Quote from: Robert Zubrin
This is a very controversial proposition and we're going to debate it.  And, I must say, that both sides here are to be congratulated for having the integrity and courage to come out and defend their point of view in clear and open debate face to face.  [Applause]  Because we've had too much in the space business of people going around saying stuff behind other people's back and not coming out in the open to say it openly and confront it.  Or other people saying things openly to the press but not being willing to come and defend their point of view.  We of course had the incident of Franklin Chang Díaz saying very detrimental things, that radiation is a show stopper on the way to Mars so we must go to Mars much quicker than is currently possible and only the VASIMR drive can enable this and thus you can't go to Mars until the Warp VASIMR is developed and you can't do your program until we do his program.  And he's been challenged to come and defend these statements repeatedly and not done it, which should tell you something that not only are his statements not defensible, but he doesn't consider them defensible.

In this case one of these two parties are wrong.  [Laughter]  But they're honest and they're willing to come out and say it.

~Kirk

Edit: Here is a link to the of the debate.  The quoted remarks above start at 2:00.
« Last Edit: 08/18/2015 10:07 PM by kdhilliard »

Offline Stormbringer

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Re: VASIMR Engine
« Reply #298 on: 08/25/2015 01:16 PM »
an article reiterating docmordrid's post's information:

http://www.space.com/30221-plasma-rocket-technology-nasa-funding.html
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Re: VASIMR Engine
« Reply #299 on: 12/03/2015 03:04 AM »
So, I am a comic book artist working on a science fiction comic book and I need help. I want to kind of base my space ships design on the VASIMR system but need help in understand how it actually works. I am a physicist and studying engineering so I have kind of an idea. But what I really want to know if the VASIMR propulsion system design can be changed for different space craft designing or if the system has to be built the way it is designed for it to actually work.

L. Monroy
MonroyART
monroyart.net

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