[belbear]

Henning wrote: I believe you’re thinking of inverters (DC->AC), not of rectifiers (AC->DC). That’s actually the beauty of FF, because you already get a inverter for free. Output capacitors are already required, otherwise you’re getting only impulses of a few milliseconds.
Or are you’re thinking of eliminating those output capacitors? And replacing them with what? Inductors of the same size? Not much gained (but might be cheaper).

Why not eliminating a separate output storage alltogether? Why not let the beam and X-ray pulses recharge the input capacitors directly using a passive high-power transmission line toward an additional set of switches on the input capacitor bank?

This way you only need to siphon off and convert to AC the net power surplus (which hopefully will be there) from the pulse-recharged input capacitor before initiating the next shot, and not having to deal with all the recycled power through your DC converter. You may need to convert the pulse to a higher voltage using some sort of pulse transformer, which can be a passive device.

When running “under-unity”, the recharger (needed for startup anyway, but can be much less powerful) needs to add only the deficit to the input capacitor, not the entire charge. This can be useful when fusion energy (beam or X-ray) is to be used for something else than electricity generation.

It will be a complicated mechanism to design, so probably only possible for a second-generation machine, but it can save a great deal of $ and bulk on power electronics when commercial competition starts to heat up.

In any case, you need a type of inverter that can take a sawtooth-shaped input voltage (>40kV, at FF pulse frequency) and block-shaped input current (constant current, briefly interrupted by the firing sequence), and produce tri-phase sinusoïdal output voltage and current, synchronized with the grid frequency (50 or 60Hz)

[belbear]

Rezwan,
You should definitely try out CamStudio, because it’s open source and noncommercial.

Which means its $-free, ad-free, nag-free, malware free…

It can capture video and audio.

I tried to upload a short snippet from your FF-youtube movie as attachment, but AVI’s (the standard type of Windows movies) are not allowed in this forum, although a great deal of other (Apple) multimedia formats are

[belbear]

Rezwan wrote: Another video capture question – is there some software for windows where you can record a clip of a playing movie? 2. How do I capture said footage. I know for mac there was this “SnapProZ” thing…

Rezwan,
There are a lot of “screen capture” (or “screen grabber”) thingies that work for streaming videos.
Many can be downloaded and at least tried out for free.
I googled for “video screen grabber” and found those for you to try out: (among many others)

http://www.screenvirtuoso.com/
http://camstudio.org/
http://www.hyperionics.com/hc/index.asp
http://all-streaming-media.com/record-video-from-screen/

Dunno about (American) copyright etc.. It all depends on what it’s used for. When used for nonprofit, i’ll doubt you will attract a lot of fire from the copyrightpolice for copying a youtube movie.

Although, as copyright laws are evolving now, the time is not far off that illegally downloading an mp3 will be punished more heavily than simply stealing a CD out of a shop. :coolhmm:

[belbear]

Nice movie, but i was hoping to see some audiovisual footage of DPF operations. (even cellphone or webcam quality is better than nothing)
I’m especially curious to know how FoFu-1 SOUNDS like when firing.

Is it an ear-shattering BANG, a muffled POP, a sharp TICK or no sound at all?

After all, if this trick is really working out, history is being made and it would be a shame that only written text and still pictures of the first experiments are available when FoFu-1 is moving to the Smithsonian in a decade or so…

[belbear]

Admin wrote:

I’m sure that Mr Lerner is garnering what knowlege he can from these other projects.

Yes, and the capacitor bank was designed with all that in mind. Still, the reality is these capacitors are not quite behaving according to design so there’s a fly in the ointment somewhere that is being systematically sleuthed out.

Are all the wires leading from the trigger box to the switches exactly the same length? i.o.w. as long as the longest one needs to be.
Even light speed is not sooo fast when it comes to nanosecond precision….

[belbear]

My favourite quote from the House hearing, from chairman Bard:

“It kinda blows your mind we’re going through all that trouble to heat water”

[belbear]

Sorry, wrong button. Now I can’t remove this….

[belbear]

While “baby” was built, things went very fast and open-sourced. This whole worldwide community was allowed to know how it works and looks like, in itself a remarkable openness in comparison to other small-scale fusion projects. Some call this an overhyped website, but I really like it. Gives me “room for thought”

Now the experiment starts taking data I presume Eric wants to keep the lid on releases because now it’s really getting serious.

The really important data, the one that shows that p-B11 break-even has occured or not, will have to be peer-reviewed before release anyway, to avoid a possible “Pons-Fleishman-disaster”. Important intermediate breakthroughs, such as confirmation of the “Lerner magnetic field effect” on electrons, will also need such a review process.

It would be real trouble if LPP first cried victory on CNN worldwide, only to find out that a fundamental mistake was made and break-even is still a long way to go or outright impossible with the available hardware.

We humans may theorize and tinker, but the physics is there since the big bang (or NOT??) and it won’t comply to our wishes.

After all, we do have some time: ITER isn’t due before 2018… 😉

However, as anyone in here, I do hope to see some intermediate results published, such as first D-D neutrons and first p-B11 fusion.

[belbear]

Tulse wrote:

Radiating waste heat into deep space isn’t so difficult, on condition you shield your radiator from the sun. After all, space shows us a 3 Kelvin black-body and that’s really cold.

Right, but that is purely radiative cooling, which as I understand it isn’t nearly as efficient as conductive or convective cooling — there’s a reason that thermos bottles use vacuum flasks. As “cold” as space may be, you can cool things far more efficiently on earth by, for example, dumping heat into a lower temperature fluid. (I’m sure that some one with way more technical expertise could clarify what sized radiator would be needed to dump 5MW of heat into space.)

Sure, radiative cooling is less efficiënt than convective/conductive, but in space that’s all you’ve got, unless you vent precious matter (such as the flash-evaporative cooling the Space Shuttle uses when its payload doors are closed)

Radiator size is not the only issue here, temperature is one too. Radiative cooling becomes more efficiënt with rising temperature (look at the Sun, that’s a very efficient radiator), so all you need to make your radiator panels smaller is to make ’em hotter.

I don’t imagine a FF spaceship at full trust using the kind of big, shiny radiators like the ISS has, I imagine them being rather small, sturdy and glowing hot. Using high-temp coolants such as molten metal rather than ammonia. Since energy is not such a scarce commodity on board a FF vessel as it is in a solar-powered one, a two-stage cooling process that steps up the temperature using some sort of refrigerator cycle can be used.

Actually both types of radiators would be needed, one high-temperature for the high-grade waste heat from the reactor and one low temperature for low-grade waste heat from electronics and life support.

p.s.: you got your quotes wrong…

[belbear]

texaslabrat wrote:
As I mentioned before, an F-16 (a small, single-engine, lightweight fighter) in full afterburner consumes the rough equivalent of 300 MW. The top speed of an F-16 in full afterburner is about Mach 2.0 at altitude. Believe me, you’re gonna need power in the GW scale to even think about a hypersonic high-altitude first stage or a hypersonic trans-continental aircraft. As a “fun fact” comparison, each of the 5 Saturn V first-stage engines consumed a heat-content equivalent of over 30GW. It’s hard to wrap your head around the shear power requirements needed for high-performance flight..but they are indeed quite steep.

Hmm, indeed quite steep. But that’s why I propose a two-stage approach (see my other post). The second fusion stage releases all its fusion energy as heat for thrust. No coils, layers or conversion losses, just pure punch. Count it out: For each p-B11 fusion 150keV goes in, 8,7MeV comes out.

It will be difficult to squeeze into an F-16, (MAYBE if you accept to expose the pilot’s balls to an unhealthy dose :sick: ) but a 100MW of electricity from stage 1 MAY be sufficient to provide the GW’s of thrust we need.
Of course it remains highly speculative until we can use data from an actual power-positive FF prototype.

[belbear]

Tulse wrote:
Thanks for clarifying that. I wonder if instead of a heat exchanger if something like a plasma torch would be more efficient, as it would use the FF electricity directly.

A plasma torch (some sort of spark inside the airstream) looks possible, but then only electricity can be used as input, not directly fusion energy. And I have no clue how sparks behave in a hypersonic airflow. Could be as problematic to keep the spark firing as combustion is. Electric discharges are doused in high-power high-voltage switches, using a jet of inert gas such as argon to “blow out” the spark like a candle flame. In a plasma welding torch, a relatively slow flow of gas is used.

I was rather dreaming of using fusion energy even more directly than electricity in a two-stage fusion engine.
My idea is to use an “externally powered” thrust-FF reactor in the engine nacelle, whose input capacitors are charged by the first-stage, ordinary electricity-producing FF unit inside the hull.
ALL of the energy output from this thrust-FF (ion beam + X-rays + electrode cooling) would then be converted directly into heat for engine thrust by releasing all them rays into a tungsten heatsink, thus multiplying the input energy directly by the achievable fusion Q-factor and greatly reducing the amount of on-board electric power needed.
Actually this second-stage FF reactor is like an over-unity plasma gun, but since FF needs a pure hydrogen-boron gas fill to work instead of air, heat needs to be exchanged.
Maybe hare-brained but I like the idea.

Tulse wrote:
I’m also still not clear on the power required, however. What kind of power density does one have to reach to match that of hydrocarbon fuel? Is such density practically achievable?

I’m not sure. The power of reaction engines is measured in thrust force (kilograms, pounds..), which is the punch you can expect, and specific impulse (in seconds), a measure for how efficiently your input energy is converted into that thrust. My guess is that specific impulse for fusion jets can be assumed equal to that of conventional jet engines, but I would need to look into how to translate electric or thermal kilowatts into thrust.
As for the power density of the actual borane fuel, so little of it will be needed to reach orbit (a few grams) that its mass is neglectable against tonnes of engine and airframe mass. When dealing with a fusion engine, the mass of fuel needed is totally irrelevant, unless you intend reaching a sizeable portion of light speed.

Tulse wrote:
I also wonder if FF won’t be far more useful in deep space, where low thrust electric propulsion systems are more practical, and where one might not need a lot of the support gear on needs in an atmosphere. For example, I presume it wouldn’t be necessary to have a vacuum pump to keep the reaction chamber evacuated in space, or to have the reaction chamber heavily reinforced to fight against implosion from atmospheric pressure. I would think a space-based FF reactor could be much lighter and smaller in space. (The one issue that might be more of a problem is dealing with the waste heat, as it it more difficult to radiate it away in a vacuum.) I would also think that the inherent simplicity of the system would be attractive, relative to fission reactors that require complex systems to turn their heat into electricity.

Of course it will. But the launcher I propose is not intended to leave the atmosphere, maybe ideally to fly into low orbit. A real deep-space engine is to be carried up as a payload.
As I mentioned in one of my very first posts here, a space-optimized FF engine could take us to the stars by beaming the alpha ion beam directly into space as reaction mass. (charge-neutralized by electron emissions, of course)
X-rays can be recuperated into electricity as usual and the eventual energy deficit of the direct-beam FF engine should be filled with energy from a FF electricity generator (also space-optimized) or by partly tapping into the beam energy. You indeed don’t need a vacuum pump, unless you find the loss of unfused reactants (especially boron) unacceptable. In that case you do need to pump them off and recycle them. Space vacuum can help with that, though.
Radiating waste heat into deep space isn’t so difficult, on condition you shield your radiator from the sun. After all, space shows us a 3 Kelvin black-body and that’s really cold.

[belbear]

There is also this old FF business plan lingering around:

http://www.integrityresearchinstitute.org/FutureEnergy/FocusFusion-Ver6.htm

I did not find a clear issue date inside :grrr: but the content suggest it must have been issued in 2003.
I guess this needs a bit of updating too?

I regret there are so many undated resources available on the web. Since electronic documents do not “age” or become gradually less available as printed media do, the correct date of origin is very important.

This also goes for forums and news articles about “new technology” and things like that, where sometimes the month, day and even time of posting are given, but not the YEAR!

As things go, I google for some info, find something that looks promising, but after some reading, the stuff appeared to be almost a decade old and reading it was a total waste of time.

Just venting some steam here, don’t mind.. :cheese:

[belbear]

Henning wrote: Lawrenceville Plasma Physics had a two-pages fold-up brochure until recently, which would have been quite a good start.

With the help of of Google I reconstructed its former location, but it has been removed: http://lawrencevilleplasmaphysics.com/media/LPP_Brochure.pdf

Maybe LPP removed it deliberately, maybe it just vanished.

I’ve printed it on paper, but I don’t have a digital copy of it anymore.

Take good care of that printout! It may once have great collector’s value. If you look at what’s now being offered for a scribble from Mr Einstein or Mr Edison… 🙂

[belbear]

texaslabrat wrote: In the mean time, I’ll still be putting my money on the space elevator tho 😉

I totally agree it will be a formidable and lenghty engineering challenge to build a fusion powered first stage launcher, but so is a space elevator. Only think of all that orbiting space junk that needs to be cleaned up before you can even start building a space elevator. It may take as well a FF launcher to do just that and pave the way for space elevators.

Just because a FF launcher can take off lightweight, it doesn’t even need those outrageous power levels and brutal acceleration associated with Saturn V rockets or Space Shuttles, so much less than a GW may do. Neutron shielding doesn’t need to be as heavy too. The crew compartment must of course be safe, but leaking some neutrons in the atmosphere is not really a problem. Cosmic radiation does similar all the time.

Once we have FF as a proven technology in the next couple of years, thousands of engineers can bend over all the new applications that are opening up.
Then, around mid-21st century, those advanced FF concepts beyond simple power production can already be realized. (even before the time of currently projected practical DT fusion)

Fusion-powered commercial airliners are one of those must-have’s before the 21st century ends, at least if the airline sector has the ambition to survive the fossil fuel era. Spaceflight can follow that research and military flight may even lead it. (they’ll definitely want unlimited-range bombers and fighters)
It not only eliminates most environmental issues ralated to aviation (CO2, soot, contrails), but also two important causes of aircraft disaster: Fire after an otherwise intact crash landing and out-of-fuel emergencies.

Hydrogen, the only other alternative, just eliminates the CO2 and soot issue and causes even more fire hazard. (remember Hindenburg and Challenger)

Passenger acceptance may be a problem in the beginning (Nuclear planes? No thanks, I don’t wanna light up in the dark), but by that time some inevitable mishaps with focus fusion units (all without dangerous radiation issues) will quickly subside fears. And what that toxic decaborane concerns: In open air, these few grams involved will quickly disperse to harmless levels. Such “minor mishaps” with dangerous chemicals are quite common in the chemical industry.

[belbear]

Tulse wrote: belbear, in the system you describe the only thing that FF would be doing is providing an alternate power source. As I understand it, the problems with scramjets aren’t in that area, but instead in the engineering of the hypersonic air passage. Perhaps I’m wrong, though — someone else here may be more knowledgeable on this topic.

The problems of designing a scramjet are mainly in how to prevent a “flameout”, i.o.w. the need to maintain fuel combustion in a hypersonic airflow.

A FF powered scramjet does not do chemical combustion at all, so this problem does not pose itself, because it would work by simple heating of incoming air (using either electricity, X-rays or ion beam) And that always work.
Instead of fuel injection it could be using a tungsten heat exchanger, operating at very high temperature (2000°C) to transfer heat from the source to the airflow.

And in aviation and space flight the weight of the fuel to carry is of course also an important issue. For a FF aircraft, the landing weight is essentially identical to the takeoff weight. Although some kind of backup fuel could be used: Kerosene or even water injection could provide an extra low-speed boost during take-off. (afterburner)

There were experiments with water injection in turbojets, and it worked, but in the end it proved more efficient to simply carry the same weight in fuel.
In contrary to fuel, water injection also works reliably at hypersonic speeds. So water injection can give the upper rocket stage that extra final boost before separation.

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