richard Dell interview -claims space propulsion breakthrough

[chrismb]

--I suggest it's probably a good time for him to give up

Well, OK, that was at the harsh end of the scale when discussing someone who has struggled so hard with his idea without bearing much fruit, and wasn't meant as a personal attack, but the other comments were meant as a general critique of the 'academic way', which is a river along which a lot of 'dead wood' floats. OK, so that is also a harsh generalisation, I'm sure there are few academics who are not 'hard-workers', but let's just look at all the fundamental breakthroughs achieved in academia in the last few decades...??...and then if no-one [especially no ex-academics] dares to posit their opinions on the underlying reasons for the rather lack-lustre performance of institutionalised science of late, for fear of hurting the feelings of a few grown-ups, then I'd say my conclusion is well-founded; that academic science is in its death-throws.

There seems to be an ever-increasing attempt to 'work-hard' in academia, but a decreasing amount of 'working-clever'. Too many 'productivity' targets, I guess.

[chrismb]

I can't imagine how I continually fall for the trap

No trap was set. You are free to blunder into whatever your inept stumbling takes you.

[chrismb]

I've mentioned particular uses for it in other threads, I was the one that originally proposed that if polywell works, larger reactors should have the ability to burn other fuel combinations--it was originally a sci-fi scene point: imagine exploring the ruins of a dead alien civilization and finding football stadium sized reactors to burn a variety of fuel.

I have gone through these calculations for my own purposes. For beam-type reactors, for which you are feeding in power to supplement coulomb collision losses, p+15N is about the last of the reactions for which that is sustainable where fusion power out is sufficiently in excess of collision-loss-makeup power in for which there would be a net benefit. p+19F* is so close to power in=power out that I don't think that could be done, and the equation is simply negative for any higher atomic mass combinations.

As for burning higher masses in a thermal plasma, Rider deals with that and there is a table somewhere of his which paints an even worse picture, due to the brems off of the larger nucleii.

So, according to my calculations at least, p+15N is about your lot.

*{edited}

[Helius]

P+19Cl isn 't a multiple of alphas. C12, P+B11, P+N15 are; so each has high binding energy per nucleon.

Where can I briefly see/read more about P+N15? I'm surprised that the reaction would sputter carbon 12; You'd think there'd be too much energy for the carbon to hold together, and instead come apart into Be and an He, then the Be would come apart into 2He as it does in a P+B11 reaction. does it spill its energy in a Gamma, or in the energy of the first alpha to prevent it?

What's the scoop? Has there been anyone whacking N12 with protons in a collider or IEC device somewhere?

[chrismb]

P+19Cl isn 't a multiple of alphas.

So sorry. My error. Got my halogens mixed up. I meant 19F.

Where can I briefly see/read more about P+N15?

see viewtopic.php?t=2808 for more...

[Brian H]

... that academic science is in its death-throws.

There seems to be an ever-increasing attempt to 'work-hard' in academia, but a decreasing amount of 'working-clever'. Too many 'productivity' targets, I guess.

Idjit! That would be "death-throes"!

Otherwise, fair comment. A condition of getting Vitamin M seems to be lack of excess ambition, scientific or departmental.

[IntLibber]

Uh, if they can get controlled fusion working, building even a modest power station --Or replacing / supplementing the fossil-fuel stages-- would pay for their space project...

Getting just one 2 GW fusion power station operating would earn so much profit at todays electic prices that you could fund a whole interplanetary space program with it.

Ideally what you do is build a 2GW power station, then an electromagnetic rail to put a launcher in the air at mach 0.9, then build your fusion launcher to use that rail, and fund the whole thing with power sales.

2 GW at $0.12/kwh means hourly revenues of $240,000.00. Annual revenues of $2,102,400,000 operating at 100%. Given lack of fuel costs and the relative simplicity and safety of a fusion system versus a fission plant, if you can't earn a 50% profit on that annually, you have to be doing something wrong.

[cgray45]

Uh, if they can get controlled fusion working, building even a modest power station --Or replacing / supplementing the fossil-fuel stages-- would pay for their space project...

Getting just one 2 GW fusion power station operating would earn so much profit at todays electic prices that you could fund a whole interplanetary space program with it.

Ideally what you do is build a 2GW power station, then an electromagnetic rail to put a launcher in the air at mach 0.9, then build your fusion launcher to use that rail, and fund the whole thing with power sales.

2 GW at $0.12/kwh means hourly revenues of $240,000.00. Annual revenues of $2,102,400,000 operating at 100%. Given lack of fuel costs and the relative simplicity and safety of a fusion system versus a fission plant, if you can't earn a 50% profit on that annually, you have to be doing something wrong.

Yep=- all these fusion space craft proposals are putting the cart before the horse in a very big way. Even from the view point of investors-- you want me to invest in something where you don't even have the engine yet? That'd be like building a model T in 1880 and telling investors "well we don't quite have the whole internal combustion design worked out yet, but once we do..."
Eyes on the prize-- and the prize here is the development of confirmed, beyond break even fusion-- once you have that, everything else will follow. Until you have that, everything else is a waste of time.

[D Tibbets]

Uh, if they can get controlled fusion working, building even a modest power station --Or replacing / supplementing the fossil-fuel stages-- would pay for their space project...

Getting just one 2 GW fusion power station operating would earn so much profit at todays electic prices that you could fund a whole interplanetary space program with it.

Ideally what you do is build a 2GW power station, then an electromagnetic rail to put a launcher in the air at mach 0.9, then build your fusion launcher to use that rail, and fund the whole thing with power sales.

2 GW at $0.12/kwh means hourly revenues of $240,000.00. Annual revenues of $2,102,400,000 operating at 100%. Given lack of fuel costs and the relative simplicity and safety of a fusion system versus a fission plant, if you can't earn a 50% profit on that annually, you have to be doing something wrong.

Fuel cost may be low, but transport costs will be high, unless you have a highly efficient booster. Then you have to consider the cost of building, operating, decommissioning, and deorbiting the station. Then you need to consider the cost of getting the energy back to the surface- look at some of the criticisms of beaming microwave energy to the Earth. You need huge antennas. Even if there is a workaround, the costs would still be considerable.
Finally, if you have a safe fusion reactor, why spend huge efforts and money for an orbital station when you could much more easily and cheaply build and operate a plant almost anywhere on the surface.
Remember, one of the claimed advantages of Polywell type reactors is that they can be scaled to more convenient sizes and be placed close to the markets. Currently, transmission costs and maintaining the infrastructure accounts for ~ 1/2 of the end cost of electricity.

Unless there are game changing technologies in multiple areas, space generated power may be useful, but only for space based use.

There is one glaring and very bright exception. That is, of course, the Sun. There the power is completely free. All you have to worry about is the capture, conversion, storage and transmission of this energy on the Earth's surface. Some might also worry about the environment effects. Some of the schemes to do this includes solar cells, solar thermal, wind mills, hydroelectric power, and of course fossil fuels. The exceptions include tidal (more Moon, than Solar gravitational energy), and geothermal energy. Fission nuclear plants could be considered an exception, except the heavy elements come from stars also. For that matter, a large part of geothermal energy is provided by radioactive decay of isotopes created in stars. Fusion power (at least D-D fusion) would be an exception to Solar (or stellar) derived power, as the deuterium came from the Big Bang, no stellar intermediaries needed.

Dan Tibbets

[kunkmiester]

dan, he was referring to a ground based fusion power station. That comes first, THEN you can build the accelerator and all that other stuff. No space based power stuff here.

[Ivy Matt]

Yep=- all these fusion space craft proposals are putting the cart before the horse in a very big way.

....

Eyes on the prize-- and the prize here is the development of confirmed, beyond break even fusion-- once you have that, everything else will follow. Until you have that, everything else is a waste of time.

I believe that depends on whether you intend to use the fusion to generate electricity to power the spacecraft, or whether you intend to use it simply for thrust. I don't know much about the efficiency or economics of using a fusor as a satellite thruster, but I don't see any conceptual problems with running one in jet (or "trumpet") mode to generate thrust. And, if fusion can be profitable before break even, you have less cause to worry about the research money drying up before you are able to reach break even.

[ltgbrown]

dan, he was referring to a ground based fusion power station. That comes first, THEN you can build the accelerator and all that other stuff. No space based power stuff here.

To err is human, he is very human, apparently.

[Nik]

Uh, if liquid hydrogen and oxygen are cheap enough, provided by your fusion plant running off-peak (making money by peak lopping) then you can accept the inefficiencies of multiple sub-optimal rocket engines arranged as a plug-nozzle and just build a VERY BIG SSTO with a production line for its ring of engines...

Ithacus, Rombus etc etc...

Over-engineering it just makes it yet another project that out-weighs its hardware by an order of magnitude...

[Tech]

So basically this project does not only need a working fusion plant but its choice is narrowed to those concepts, which are physically small, so this excludes such monstrous devices like tokamaks. At least the whole ITER will be big like an aircraft carrier, but who knows how much place could you save by not needing so much auxiliary equipment as you need for a working land based power plant (of course this applies not only to tokamaks).

[D Tibbets]

George Miley has proposed a fusor as a replacement for typical ionengines

In space you may not need a vacuum chamber and associated pumps. You still might need some shielding, and cooling will require large radiators.
My current impression is that the fusion fuel burn up is good, so you don't need to worry about losing fuel ions directly, but electron losses need to be matched by ion dumping to keep the spacecraft from becoming charged. Granted a thin shell without pumps could be rigged to capture the electrons. Of course then you have to consider how to balance the fusion ions emitted. Perhaps most (?) of the lost electrons should be let go after all.

Dan Tibbets