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#1 2004-10-21 16:27:09

jabe
Member
From: toronto Canada
Registered: 2003-10-02
Posts: 24

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Read about Vasimr a few years ago but haven't heard much of any updates on the technology.  I thought it would have come up in the news since the money seems to be there for more rocket engine development.  Any one know of any updates?  Can't seem to find any through google
cheers
jb[/color:post_uid0]

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#2 2004-10-21 18:09:07

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]NASA has tried to kill the program once or twice, failing only because a seasoned astronaut was on the team... basicly, VASIMR is still a next-generation thing without megawatt scale power supplies, which won't be around any time soon. The JIMO reactor will make about 0.1MW, the ISS makes about 0.18MW, and planned future reactors will make like 0.3MW.

As far as I know, the program is still ongoing, but with so little funding that they can't get much done. It really will require next (or even next-next) generation power sources to make enough energy to run it like the far-out vapor core fission reactor, but at least needing somthing much bigger then what we have or is proposed.[/color:post_uid0]


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#3 2004-10-21 21:02:36

MarsDog
Member
From: vancouver canada
Registered: 2004-03-24
Posts: 852

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Lot of links

VASIMR "a power-rich, fast-propulsion architecture" that could lead to fusion rockets

Beamed power to start a fusion rocket, and hope nothing gets in the way.[/color:post_uid0]

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#4 2004-10-22 08:52:12

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Even if they can work the bugs out of the plasma dynamics part, and make all the nessesarry magnets and EM generators work without being too fragile or heavy, there is still the need for power. Lots of power. More then ten times the power of any proposed near-term space power reactor, forty times the power of the little JIMO reactor, and so on. The VASIMR engine is an engine, you still have to get the energy to feed it from somewhere.[/color:post_uid0]


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#5 2004-10-22 13:55:55

Euler
Member
From: Corvallis, OR
Registered: 2003-02-06
Posts: 922

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Even if VASIMR can be made to work efficiently and reliably, it would still only be a relatively minor improvement over other types of modern electric engines.  At this point electric engines are good enough that far more progress can be made by improving the power plant than by improving the engine itself.[/color:post_uid0]

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#6 2004-10-22 15:19:51

MarsDog
Member
From: vancouver canada
Registered: 2004-03-24
Posts: 852

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]

The lab director is NASA astronaut Franklin Chang-Diaz, a long-time plasma rocket believer who has been hard at work on the idea since 1979. He holds a doctorate in applied plasma physics and fusion technology from the Massachusetts Institute of Technology (MIT)[/quote:post_uid0]

If he can figure out how to fuse the exhaust,
then the engine also becomes the power source.

When efficient fusion reactors ?[/color:post_uid0]

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#7 2004-10-22 15:25:36

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Reading one or two of these articles, you really have to ask... are these VASIMR guys serious? Talking about [i:post_uid0]two hundred[/i:post_uid0] megawatt power supplies as "ideal," and even more reasonable figures in the 4-6MW range, which would require multiple conventional reactors. How much of the ships' weight is going to be power supply?

Since the VASIMR's only real advantage over ion drives is a high-thrust setting, I wonder how much thrust an ion engine could be coaxed into producing if it carried a ~1.0MW power supply. Perhaps carry two sets of ion engines if they aren't too heavy, one for high thrust/low-Isp and one for cruise. Keeping the ship neutrally charged might be a challenge though. And we'll have to use somthing besides Xenon unless new supplies of it are made available.

I'm still a big fan of thermal engines... you don't waste time accelerating, it doesn't have to work for months/years non-stop, and so on.[/color:post_uid0]


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#8 2004-10-22 15:31:36

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]A fusion reactor would definatly make the VASIMR a much more attractive option, but at this rate, a practical and portable space fusion reactor is somthing that I don't think is very likly we'll see in our lifetimes... if it is, it will be at the twilight of mine.[/color:post_uid0]


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#9 2004-10-22 16:19:51

Ad Astra
Member
Registered: 2003-02-02
Posts: 584

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]We should view VASIMR as the next step beyond a JIMO-scale reactor and bi-modal nulear thermal rockets.  NTR's will force the development of more efficient space reactors for both propulsion and electrical power.  A 4-6 MW reactor for VASIMR will follow on its coattails.[/color:post_uid0]


Who needs Michael Griffin when you can have Peter Griffin?  Catch "Family Guy" Sunday nights on FOX.

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#10 2004-10-22 17:11:20

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]I doubt that Ad Astra... the trend in NTR engines is to make them smaller and burn up their fuel quickly, not bigger like VASIMR would need. Bimodal rockets will only produce enough electricity for smaller applications like life support and science, not the massive megawatt requirements for a VASIMR.

The basic principles for an NTR engine are infact inherintly opposed to using the reactor for power generation, to make them run [i:post_uid0]hot hot hot[/i:post_uid0] and to weigh as little as possible by making the core as small as possible, which will be no good for power generation of that magnetude.

To make power, the core can't operate at the superhot temperatures needed for really efficent rocket propulsion... The current schema now is to put the nuclear fuel into a ceramic or graphite grid and just pump LH2 past it since this configuration could run [i:post_uid0]really[/i:post_uid0] hot, increasing Isp by ~200 seconds, but wouldn't be very useful for power. For a power reactor, you need a metal core for efficent heat transfer , and you simply can't make those hot enough to reach 1000sec Isp without melting the metal plumbing of the coolant loop.

The reactor size needed to make ~10MW will also be pretty huge, there just won't be any NTR analouge to such a reactor that big, nor would a bimodal rocket make electricity as well as a purpose-built one and couldn't run as hot to make a good NTR rocket. Jack of all trades, master of none.[/color:post_uid0]


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#11 2004-10-22 17:43:43

Martian Republic
Member
From: Haltom City- Dallas/Fort Worth
Registered: 2004-06-13
Posts: 855

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Basically what I'm hearing is that a VASIMR project will be basically just a science project for the conceviable next twenty to thirty years. Even with a few break throughs in different areas, it will still be basically just a science project. Even if something really big breakthrough where to be accomplished in the VASIMR field, it would still be questionable as to it usefullness for space flight.

Larry,[/color:post_uid0]

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#12 2004-10-22 17:59:39

Euler
Member
From: Corvallis, OR
Registered: 2003-02-06
Posts: 922

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]

Since the VASIMR's only real advantage over ion drives is a high-thrust setting, I wonder how much thrust an ion engine could be coaxed into producing if it carried a ~1.0MW power supply.[/quote:post_uid0]

Assuming it is running at about 3000s isp, the ion engine would produce around 50N of thrust.  The VASIMR studies that I have seen do not have any very high thrust modes.  Usually, the minimum isp (maximum thrust) is 3000-5000s.  However, an advantage of VASIMR it that, in theory, it can vary its isp over a wide range (with the maximum value of 50,000s or higher) without much loss in efficiency.  The other advantages are that (according to it's proponents) it will be very reliable, and it will have a very high specific power level.

Perhaps carry two sets of ion engines if they aren't too heavy, one for high thrust/low-Isp and one for cruise. Keeping the ship neutrally charged might be a challenge though. And we'll have to use somthing besides Xenon unless new supplies of it are made available.
[/quote:post_uid0]

All you have to do is to change the isp of an ion engine is to change the grid voltage.  While that is not quite as easy as it sounds, it can be accomplished and there should be no need for two engines.

Studies of missions using ion engines generally assume that the engine will be about 1/5 to 1/10 of the mass of the reactor that powers it.

Reading one or two of these articles, you really have to ask... are these VASIMR guys serious? Talking about two hundred megawatt power supplies as "ideal," and even more reasonable figures in the 4-6MW range, which would require multiple conventional reactors. How much of the ships' weight is going to be power supply?[/quote:post_uid0]

They just do that in order to get more funding.  They know that proposed mission plans with VASIMR will be compared with plans using conventional electric engines.  In order to look like they have a big advantage over other electric engines, they assume that they will have a more powerful, more advanced reactor powering their engine.  It is all about making their engine look like it has a bigger advantage then it actually does.[/color:post_uid0]

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#13 2004-10-22 18:02:51

Euler
Member
From: Corvallis, OR
Registered: 2003-02-06
Posts: 922

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]

Basically what I'm hearing is that a VASIMR project will be basically just a science project for the conceviable next twenty to thirty years. Even with a few break throughs in different areas, it will still be basically just a science project. Even if something really big breakthrough where to be accomplished in the VASIMR field, it would still be questionable as to it usefullness for space flight.[/quote:post_uid0]

The people working on VASIMR say that they could have a prototype woking on ISS or on an unmanned probe in about 5 years.  However, I don't know how efficient or reliable they could make the engine for such a near term project.[/color:post_uid0]

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#14 2004-10-22 19:06:29

MarsDog
Member
From: vancouver canada
Registered: 2004-03-24
Posts: 852

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Despite all attemps to confine plasma in a fusion reactor, it manages to escape.
Design for an escape hole and call it a rocket engine ?
-
A laser beam can be focused, cancelling atmospheric abberations, by self correcting mirrors. When will this be done for plasma confinement ?[/color:post_uid0]

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#15 2004-10-22 19:47:45

Martian Republic
Member
From: Haltom City- Dallas/Fort Worth
Registered: 2004-06-13
Posts: 855

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]

Basically what I'm hearing is that a VASIMR project will be basically just a science project for the conceviable next twenty to thirty years. Even with a few break throughs in different areas, it will still be basically just a science project. Even if something really big breakthrough where to be accomplished in the VASIMR field, it would still be questionable as to it usefullness for space flight.[/quote:post_uid0]

The people working on VASIMR say that they could have a prototype woking on ISS or on an unmanned probe in about 5 years.  However, I don't know how efficient or reliable they could make the engine for such a near term project.[/color:post_uid0][/quote:post_uid0]
[color=#000000:post_uid0]According to that artical, they wanted a rack on the ISS so they could mount there rocket to do a proof concept test firing of there VASIMR rocket. Now if it boosted ISS up a little bit when it needs to be rebusted, that just an added bonus to testing of there rocket. After all, the ISS is suppose to be a science vehicle, so they would like to do science projects on it. If they do come up with something, that would be the place to test it. So I kind of agree with them on that point.

Larry,[/color:post_uid0]

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#16 2004-10-23 07:39:37

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]Despite all attemps to confine plasma in a fusion reactor, it manages to escape.
Design for an escape hole and call it a rocket engine ?
-
A laser beam can be focused, cancelling atmospheric abberations, by self correcting mirrors. When will this be done for plasma confinement ?[/color:post_uid0][/quote:post_uid0]
[color=#000000:post_uid0]Trouble is, if it escapes too readily, it won't fuse.

A correcting laser beams and plasma beams are an entirely different ballgame, "adaptive optics" doesn't do a thing for you in plasma dynamics.[/color:post_uid0]


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

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#17 2004-10-23 15:25:06

MarsDog
Member
From: vancouver canada
Registered: 2004-03-24
Posts: 852

Re: Vasmir update??? - any new news??

[color=#000000:post_uid0]As a researcher evaluated,
the failure of fusion is due to insufficient modeling before building.

In adaptive optics, a mirror can be distorted, anticipating and counteracting the atmospheric distortions, to focus a laser beam onto a missile.

Similarly, the plasma confining magnets (magnetic mirrors) need to anticipate and  counteract the escape attempts of the plasma. If the plasma has not been accurately modeled, and the magnetic field adjusted to block, the plasma finds an escape.

Fusion Rocket Engine is easier to build than a confined electric power reactor.
The problems get blown out with the exhaust.

"You could get to the inner planets in less than a week," Cassenti said. "This is tourist stuff." Jupiter would take less than a month, allowing "settlement trade."[/quote:post_uid0][/color:post_uid0]

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