Author Topic: Nasa supports fusion based pulsed rocket.  (Read 3709 times)

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Offline Mel Vixen (OP)

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Nasa supports fusion based pulsed rocket.
« on: April 11, 2013, 08:12:05 AM »
As the tittle says. A nice write up can be found at the "Washington university. (Also you might want to look at the list of papers by MSNW there is a nice poster)

Some more source material can be found at nasas own page.

The stuff looks promising though some numbers sound unbelievable. For example the estimated Fuel-economics. 1 "grain"/"drop" of fuel in this rocket will supplement 3.7 liters (~1 galons) of bog-standard Rocketfuel. Travel times to Mars shrink towards 30-90 days (depending on relative positions).
The drive itself needs only 200 KW/h power (around 5 of Nasas new A-SRG developed for a moonbase or about the same amount the solar the ISS has)

According to the nasa-page the exhaust velocity is >30Km/s 
« Last Edit: April 11, 2013, 11:07:42 AM by Heph »
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Offline Charlie Beeler

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Re: Nasa supports fusion based pulsed rocket.
« Reply #1 on: April 11, 2013, 10:35:18 AM »
Your links need some editting.  drop the leading http://%22 and the trailing %22 should be all that is needed.
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Offline sublight

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Re: Nasa supports fusion based pulsed rocket.
« Reply #2 on: April 11, 2013, 10:51:12 AM »
Your links didn't work for me, so reposting link to research poster.

The poster claims 5000 isp (49 Km/s) with 20,000% power efficacy. (180 kW electric in, 36 MW of thrust out). The resulting 1470 N of thrust would provide a starting acceleration of 0.01 m/s. That's enough to go from LEO to martian orbit within the claimed 90 days, but I don't think a round-trip flight in less than 60 days is physically possible at that acceleration for any planetary positioning.


I hope the guys build a prototype for a space-flight demo soon. The numbers are so good I'm going to have trouble believing the system works until they do.
« Last Edit: April 11, 2013, 10:58:35 AM by sublight »
 

Offline niflheimr

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Re: Nasa supports fusion based pulsed rocket.
« Reply #3 on: April 11, 2013, 11:00:43 AM »
Very interesting - 5000s isp is more than enough , and the thrust is decent - at least twice as good as an ion drive.

If they can get the funding for a full-scale rocket we might have actual space industry sooner than I thought.
 

Offline Mel Vixen (OP)

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Re: Nasa supports fusion based pulsed rocket.
« Reply #4 on: April 11, 2013, 11:03:59 AM »
Links cleaned up :) Different versions of the BB-code using forums just handle them differently and i wasnt sure how it was here.

The 30 days thing came from the article by the Washington university, Quote:

Quote
Slough and his team have published papers calculating the potential for 30- and 90-day expeditions to Mars using a rocket powered by fusion, which would make the trip more practical and less costly.

edit: i guess you could get 30 days by scaling up and increasing the power of that engine.

And for my personal Techchart:

Humans of Earth

Railguns: Velocity 1, 20 CM
lasers: Infrared 15 cm
Power&Propulsion: "Nuclear"/"Fusion" pulse engines

Damn impressive without TN tech XD
« Last Edit: April 11, 2013, 11:13:50 AM by Heph »
"Share and enjoy, journey to life with a plastic boy, or girl by your side, let your pal be your guide.  And when it brakes down or starts to annoy or grinds as it moves and gives you no joy cause its has eaten your hat and or had . . . "

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Offline oldark

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Re: Nasa supports fusion based pulsed rocket.
« Reply #5 on: April 11, 2013, 03:11:51 PM »
Aww don't post things like that. I just got my major changed from Aeronautics/Propulsion Engineer to Computer science earlier this year and now I want to go back.  :)
 

Offline sloanjh

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Re: Nasa supports fusion based pulsed rocket.
« Reply #6 on: April 12, 2013, 08:22:46 AM »
My "cold fusion" detectors went off on this one.  Why do they think they can get the apparatus for doing this into anything remotely resembling a launchable package when IIRC the plans for the next generation fusion reactor make it the size of a medium-sized building (and probably don't exceed break-even by very much).

John

PS - By "cold fusion" I mean "highly exaggerated claims about a technically impractical process".  I actually wasn't paying attention to the "fusion" part when i typed it :)
 

Offline sublight

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Re: Nasa supports fusion based pulsed rocket.
« Reply #7 on: April 12, 2013, 09:09:20 AM »
*Nod* My own "cold fusion" detector was why I ignored the news for the first few days, but it eventually occurred to me that one of the biggest problems with existing protype fusion reactors is containment. If a fusion rocket worked by deliberately venting containment in one direction for action-reaction thrust then it would probably be technologically simpler in design than a fusion power plant.

I still want to see a prototype demoed in space, but I'm cautiously optimistic.
 

Offline Charlie Beeler

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Re: Nasa supports fusion based pulsed rocket.
« Reply #8 on: April 12, 2013, 09:13:17 AM »
John, If I'm reading the NASA writeup correctly the intent is a space only system and not a planetary interface system.  

Personally I've got a couple of problems with what I interpret from NASA's site.  If I'm reading correctly, this drive functionally uses the inner lining of the rocket motor as the reaction mass (and that is probably very much the wrong term).  And the second is no mention of just how massive the external power source will need to be to run this rocket motor.
Amateurs study tactics, Professionals study logistics - paraphrase attributed to Gen Omar Bradley
 

Offline Mel Vixen (OP)

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Re: Nasa supports fusion based pulsed rocket.
« Reply #9 on: April 12, 2013, 10:15:50 AM »
Another Article metioned "200 KW" for the entire compression - my guess is that they need 200KW of continuous power which is stored in capacitors. Iirc the "Liners" (i guess a couple of hundred in the final version) are stored on the rocket and get reloaded. The animation does seem to support that.

As for the skepticism: I included the article here because there were 2 reliable sources Nasa and Washington U. Still, as i said, the numbers sound off but stranger things happened. Another thing is that many of the pre-requisite techs like the compression of the liners are tested according to those article. Quote:

Quote
Slough and his colleagues at MSNW think so. They have demonstrated successful lab tests of all portions of the process

If i understood the function of this thing right, one could see the Rocketmotor as giant spark-plug. The magnets are strong enough to initiate compression and fusion. They are not strong enough to contain and stabilize the reaction for a longer time which is done in an actual reactor like a tocamac or stellerator. Those (Multi GW) generator types also keep a much bigger amount of plasma contained and heated via some serious Microwaves for a continuous fusion.

Other types of Fusion reactors are much smaller and do work pulsed. Take for example the Fansworth-Hirsch Fusor - this type is used as pulsed neutron source and these Fusors are the size of my washing machine ;). So a pulsed fusion motor doesnt sound to outlandish to me.

Well we can keep an Eye on it and maybe we see a Demonstration of this thing at soon as the W.U. article indicates:

Quote
Now, the team is working to bring it all together by using the technology to compress the plasma and create nuclear fusion. Slough hopes to have everything ready for a first test at the end of the summer.
« Last Edit: April 12, 2013, 10:21:42 AM by Heph »
"Share and enjoy, journey to life with a plastic boy, or girl by your side, let your pal be your guide.  And when it brakes down or starts to annoy or grinds as it moves and gives you no joy cause its has eaten your hat and or had . . . "

- Damaged robot found on Sirius singing a flat 5th out of t
 

Offline Paul M

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Re: Nasa supports fusion based pulsed rocket.
« Reply #10 on: July 10, 2013, 04:15:38 AM »
As optimistic as the article by NASA sounds it is a few order of magnitudes behind reality.

Please look at Sandia Laboratories web page for details on the Z pinch manchine.  This machine has not achieved fusion.  The problem is the requirement to achieve a uniform implosion to produce a uniform heating of the fusion fuel and get fusion to occur.  The NASA proposal is only worth even considering if they show they achieve fusion, and I am not holding my breath.

Those "fusors" mentioned have nothing to do with fusion reactions, they are simply D-D reactions that produce neutrons. 

It is also worth pointing out that the Z machine produces intense X-ray bursts when it fires, so I am a bit mystified by the whole "the ship will be isolated from the energy emissions by the thick compression material" statements.   Without more concrete results it is basically in the "works well theoretically, but like spit in practice" catagory.  Demonstrating that all individual parts work but not showing a working prototype on general principles raises my concern as well.  As a drive system for a science fiction game/book/movie it has the advantage of that it would work (baring technical realities) but as something I expect to see deployed any time soon...again I would not hold my breath.

Sorry for raining on the parade.
 

Offline Charlie Beeler

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Re: Nasa supports fusion based pulsed rocket.
« Reply #11 on: July 10, 2013, 07:28:05 AM »
Paul not to worry.  I ran this one by a propulsion (works at Dryden) engineer I know and he also calls it so much hype and bs.
Amateurs study tactics, Professionals study logistics - paraphrase attributed to Gen Omar Bradley
 

Offline Paul M

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Re: Nasa supports fusion based pulsed rocket.
« Reply #12 on: July 10, 2013, 09:15:46 AM »
It has all the hallmarks of what my supervisor called "accentuating the positive and downplaying the negative" at the end of the day.

At the coffee discussion I brought it up and generally speaking most of the comments were of the doubtful nature.  It was questioned even if it would work theoretically due to the fact getting sufficient compression to bring a plasma to ignition conditions seems doubtful.  Mind you this is what that part of NASA is mandated to explore so principally there is nothing wrong with them supporting the research.  You never know if something viable will come out of some off the wall study.