Magbeam Propulsion

If polywell fusion is developed, in what ways will the world change for better or worse? Discuss.

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djolds1
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Magbeam Propulsion

Postby djolds1 » Wed Jul 23, 2008 8:48 pm

Another option - Magbeam

Uses focused plasmas, perfect topic for a Polywell board. 8)

http://www.nasa.gov/vision/universe/sol ... gbeam.html

Open the PDF at the bottom and go to slide 43.

Suborb rocket boosts itself to 3000m/s or so. Cheap. Then the High Power Platform takes over, and boosts the suborb to orbit or beyond. Thus the rockets don't need huge quantities of high thrust low performance fuels on board to burn.

Virgin Galactic could actually open up space with these. I'd been writing off the new private companies as fads and toys of tech geek billionaires. Perhaps not so much. Even without QED, this has potential. Fuel needed for the magbeam is still noteworthy, but not terrible. Would like to dump the rare gases like argon tho...

Me want. :lol:

Duane
Vae Victis

Keegan
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Postby Keegan » Mon Jul 28, 2008 3:31 am

To make this system a reality, the primary challenge that must be overcome is keeping the plasma beam focused over long distances.


Challenging to put it mildly.

It apears the beam system would reside in Orbit. So the Main problem would appear to be - How are you going to power it ? Solar panels seem anemic at best. Beaming Power from earth has been proven again to have critical losses from the atmosphere. So the only way you could get this happening would be power from a Orbiting Polywell.

So if you do manage to get a Polywell in Orbit, it seems there would be better ways to utilise it.

A roundtrip Mars mission could be completed in about 90 days using the Magnetized Beam Plasma Propulsion (Magbeam) system


I remember reading that a BFR based QED or BFR powered Ion Drive could get you to Mars in 3 weeks. Quicker trips reduce the wieght needed for Life support and minimise the chance of anything bad happening. Also bringing a reactor with you can let you do other usefull things. Alpha particles and Carbon can produce Oxygen.
Purity is Power

djolds1
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Postby djolds1 » Mon Jul 28, 2008 5:06 pm

Keegan wrote:
To make this system a reality, the primary challenge that must be overcome is keeping the plasma beam focused over long distances.


Challenging to put it mildly.

It appears the beam system would reside in Orbit. So the Main problem would appear to be - How are you going to power it ? Solar panels seem anemic at best. Beaming Power from earth has been proven again to have critical losses from the atmosphere. So the only way you could get this happening would be power from a Orbiting Polywell.

So if you do manage to get a Polywell in Orbit, it seems there would be better ways to utilise it.


There are other options for power - space based fission reactors, or regenerative solar thermal plants which would require a large reflector but no photovoltaic cells. I'm sure there are others as well.

I was thinking that the main problem would be getting the fuel to orbit, but if the mass ratio is 7:10 as advertised (7 units of fuel per 10 units of cargo), a slow exponential progression to fill the tanks can be used. Albeit extremely wasteful of remass.

Keegan wrote:
A roundtrip Mars mission could be completed in about 90 days using the Magnetized Beam Plasma Propulsion (Magbeam) system


I remember reading that a BFR based QED or BFR powered Ion Drive could get you to Mars in 3 weeks. Quicker trips reduce the wieght needed for Life support and minimise the chance of anything bad happening. Also bringing a reactor with you can let you do other usefull things. Alpha particles and Carbon can produce Oxygen.


Certainly. This is an option if Polywell fails or does not pay out in the near term. A potential method to allow relatively rapid mass population access to space without the technical uncertainty and long time lag of a space elevator. Might be able to get it up to initial operation with one Nova-class launch (400-500 tonnes to LEO). Using this the Virgin Galactic suborbital Spaceship Two could achieve orbit. And as the wag goes, once in LEO you're halfway to anywhere.

Duane
Vae Victis

djolds1
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Postby djolds1 » Fri Aug 01, 2008 7:37 am

Vae Victis

tombo
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Postby tombo » Sat Aug 02, 2008 5:06 am

I would expect such a system to be extremely vulnerable to solar flares etc.
Even without them I see quite a complicated ion path through the earth & sun magnetic fields to hit a distant spacecraft.
However, it may be possible for the power satellite to use a similar system to harvest fuel from the solar wind, ala the Bussard ram scoop.
Or, to send fuel up from a high altitude balloon or aircraft on earth.
(Earth's moon has no volatiles to speak of so a power source there would still have to be fueled, but some of the outer moons do for local and return trips.)

The MagBeam makes me think of Dr. Bussard's magnetic ram scoop with a supercharger added.

(There were so many typo's in that NASA article that it made me lose a bit of confidence in it.)
-Tom Boydston-
"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein

MSimon
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Postby MSimon » Sat Aug 02, 2008 6:40 am

Tom,

I liked the idea of the separation of moving charges creating a net fields.
Engineering is the art of making what you want from what you can get at a profit.

tombo
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Postby tombo » Sat Aug 02, 2008 7:55 am

Yes, that is interesting and seems to be the core of their effect.
I can't wrap my mind around that part and I'm not sure I buy it yet.
I seems backwards re Lenz's law.

But, an effect like that would have a huge impact on the Polywell solutions.
Self focusing plasma beams look like either an aid to convergence or a short to the wall.
It might lead to a method of controlling the escaping plasma plumes and recovering their energy.
-Tom Boydston-

"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein

MSimon
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Postby MSimon » Sat Aug 02, 2008 1:41 pm

tombo wrote:Yes, that is interesting and seems to be the core of their effect.
I can't wrap my mind around that part and I'm not sure I buy it yet.
I seems backwards re Lenz's law.

But, an effect like that would have a huge impact on the Polywell solutions.
Self focusing plasma beams look like either an aid to convergence or a short to the wall.
It might lead to a method of controlling the escaping plasma plumes and recovering their energy.


Actually you see this sort of thing in electronics all the time. If you want the fields to cancel (no radiation) the current carrying conductors must be in close proximity.

Think of the difference between an antenna and a twisted pair.
Engineering is the art of making what you want from what you can get at a profit.

Roger
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Postby Roger » Sun Aug 03, 2008 1:09 am

Keegan wrote:QED could get you to Mars in 3 weeks.


IIRC Mars in 35 days, Saturn in 76 days
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

Jeff Peachman
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Postby Jeff Peachman » Mon Aug 04, 2008 3:49 pm

Roger wrote:
Keegan wrote:QED could get you to Mars in 3 weeks.


IIRC Mars in 35 days, Saturn in 76 days


That's more a design issue. If you want to make it in 3 weeks rather than 35 days, you simply have to increase the mass fraction of your spacecraft.

IIRC, when bussard wrote about his concepts, the mass fractions of the spacecraft were lower than a lot of modern spacecraft to show how much extra mass you could carry on a fast mission with ample margins...

-Jeff
- Jeff Peachman

Jeff Peachman
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Postby Jeff Peachman » Mon Aug 04, 2008 3:51 pm

I should probably add, even though I said "simply increase the mass fraction" it isn't always so simple...
- Jeff Peachman

choff
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fusion rocket propulsion/interstellar flight

Postby choff » Mon Aug 11, 2008 4:49 am

I've always thought one way to improve on the time required to accelerate/decelerate fusion engine spacecraft to light speed would be to send crewless AI computer run ships ahead with the fuel, let them make the long trip. Then send the humans much later to the final destination on ships with just the human habitat and the engines, no fuel to weigh them down. Have tanks of fuel positioned along the beginning of the flight path. When the crew ship gets close they beam the fuel directly into the engine intakes, accelerate the crew ship to light speed fast. At the other end of the flight the crewless ship is waiting to dump fuel into the crew ships path to power a rapid deceleration. The computer run ship could even be used on the other end to manufacture more fuel while its waiting.
CHoff

Jboily
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Postby Jboily » Wed Sep 03, 2008 4:07 pm

tombo wrote:I would expect such a system to be extremely vulnerable to solar flares etc.
......
(There were so many typo's in that NASA article that it made me lose a bit of confidence in it.)

Tom,

Take a look at;

5.2. Deflection by the Ambient Magnetic Field. The presence of an ambient magnetic can potentially modify the beam propagation. If the beam propagation is parallel to the beam then the ambient field will actually minimize beam dispersion while if perpendicular it will impede the beam propagation. In the latter case, beam deflection will occur if the beam density becomes low relative to the ambient magnetic field (i.e. low β). As noted above the prototype produces magnetic field perturbations of the order of 20 G downstream from the beam, which is much greater than the terrestrial field at about 0.3-0.4 G at the ionosphere and the 10’s nT in the magnetosphere. Thus, the worse conditions are in the ionosphere. If one assumes that self-focusing of the beam occurs at an energy density much higher than the ambient magnetic field energy density then the beam will be able to push the ambient field out of its way once the region is mass loaded by the beam plasma

The beam does appear to be quite robust against disturbances.

It also seem to be attracted to the target coil (I do not quite get this one, but it seems that they have done some testing to verify this)

As for the spelling, I do many of them :oops: , English is my second language. I usually hire a secretary to check over my writing, but it is hard to find one qualified in physic and engineering.

tombo
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Postby tombo » Wed Sep 03, 2008 8:09 pm

Good. I'm glad it looks like the beam could be made to be stable.
Thank you for pointing out that section. That is encouraging

In my opinion a good editor can make all the difference between getting follow-on funding and having a dead end project.
It certainly helps readability for the reviewers. And, you certainly want to please them.
From the looks of the equipment in this experiment, the cost of a couple of hundred dollars for an editor would be a drop in the bucket.
I have a neighbor who is a freelance editor for science articles, dissertations etc.
His specialty medical journals, but that is just where he built his clientele.
His warranty is: “if you don't like it you don't have to pay.”
He also says that he does not need to understand the content very well. He only needs to know just enough to get it to make sense. He does not correct any of the content or substance of the paper.
It's a nice gig, one that I would not mind getting into.
-Tom Boydston-

"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein


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