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  • #430
    Avatarrashidas
    Participant

    How much of a problem will the X rays produced from the focus fusion reaction be? Will a significant amount of energy be lost through X ray production? Does the technology exist to convert X rays directly into electricity or will doing this take a long time to perfect?

    #2197
    AvatarTransmute
    Member

    The people here claim they can reduce x-ray lose to acceptable levels because the powerful magnetic field can reduce electron-ion collisions and thus reduce bremsstrahlung losses. Even so they seem to hint that a several megawatt reactor will produce dozens or even hundreds of kilowatts of x-rays.

    Yes it is possible to convert x-rays into energy directly (or indirectly by converting them in to heat) direct conversion of x-rays is not a developed technology though. The x-rays could be used to polymerize light hydrocarbons though but that is a idea for another thread.

    #2213
    AvatarAlex Pollard
    Participant

    My understanding is that X-ray capture is necessary to achieve break-even for focus fusion, in addition to capturing the ion beam.

    Eric Lerner has some IP in the area though.

    See

    http://www.lawrencevilleplasmaphysics.com/business_plan.htm

    #2214
    AvatarTransmute
    Member

    The simulation showed that the ratio of fusion yield/gross input energy rose from 0.067% at 0.75MA to 5% at 1MA to 24% at 1.5MA. The optimum case studied is for a current of 2.0 MA, cathode radius 3.3 cm, and final magnetic field 12 GG. This simulation case produced a beam that carried 97% of input energy and x-rays that carry 57% of input energy. In practical terms this means that if the beam energy recovery efficiency is 90%, which is reasonable, net energy production occurs with x-ray energy recovery rates above 22%, which is easily achievable. Another practical energy-producing combination simulated used an 80% beam recovery and 80% x-ray recovery for an overall efficiency of 43%. In this example, the net electric energy production is 3.1 kJ per pulse or 3.1 MW for a 1 kHz pulse rate.

    This is rather grave, if I

    #2215
    AvatarDuke Leto
    Member

    I always assumed X-Ray recovery was just a modified Photovoltaic cell. It’s just a matter of adjusting the frequency… Kenneth.

    #2216
    AvatarTransmute
    Member

    Yes you could make photovoltaic systems that convert x-rays but there efficiency and lifespan would be very questionable. It seems that Focus fusion relies and not one but two major breakthroughs: Focus fusion and high efficiency x-ray photovoltaic. Either that or you going to need both heat engine cooling and a decelerator just to break even which would make a DPF fusion reactor much more costly. Although even if DPF does end up needing a steam engine and cooling towers it would still be economically competitive with coal and even nuclear power, just not by as much.

    #2218
    AvatarHenning
    Participant

    There is a company called Power Chips which claims being able to convert heat to energy by a so-called Avto Effect (see Avto Metals) – all owned by a cooperation called Borealis.

    That Avto Effect is based on the fact, that an excited electron (heat) that hits a wall with gaps finer of its own wavelength must release its energy to exist (some quantum effects stuff). Please read the details on their web page.

    The same should be possible with photons (they’ve got a Photon Power site, now a little bit defunct). X-ray photons would require much finer gaps, so x-rays would be still a challange.

    #2219
    AvatarTransmute
    Member

    I’ve known of them for years, but have yet to see them make a significant product. Its just electron tunneling that overcomes the problem with normal thermalcouplers of heat conductivity: make a nanometer gap where electron can jump but heat can

    #2220
    AvatarAaronB
    Member

    Bremsstrahlung (x-ray) losses have traditionally been one of the big obstacles of maintaining a fusion reaction. To overcome those losses, we are trying to take advantage of the magentic field effect, which will reduce the amount of x-rays generated, as described above. To do this, we are playing with the shape and size ratios of the anode/cathode. This ratio, as well as the timing and size of the current pulse, should produce the large magnetic fields that are needed in the plasmoid. However, there will still be x-rays produced, which would be lost energy if it couldn’t be captured and converted into useful energy. The third part of the patent application is related to this. https://focusfusion.org/index.php/site/article/lpp_submits_patent_application/ The magnetic field effect will be tested and refined as part of the collaboration with the Chilean Nuclear Commission over the next three years. https://focusfusion.org/index.php/site/article/lpp_cchen_collaboration_announcement/

    #2221
    AvatarElling
    Member

    AaronB,

    please stick to the xrays. Eric has claimed before that xray recycling is not a problem. That’s reassuring and bold at the same time inasmuch as there should robust technology to back up such a claim. I can’t see why you would want to black out the technical details on this since the patent is all about the general application and not the specific implementation, I hope. We have enough of unadressed issues on an openended timeline already. I think you can be more open with the details, that will add cred and patience among potential investors.

    Bussard was very generous with details on his IEC. Nobody’s gonna be able to cannibalise the IEC or the FF reactor anyway.
    There’s a LPP projection but it hasn’t been updated. More sceduled mile stones are needed.

    #2222
    AvatarAaronB
    Member

    Elling,

    It sounds like you are looking for more technical details and a defined timeline. I’ll defer to Eric to decide how much detail to give out at this time, but keep a couple things in mind. The patent application was sent in about a year ago, and it usually takes a year and a half to two years for the patent to be issued. As much as we would like to speed up that process, we can’t. When it is issued sometime in the next year, you’ll be able to read through it online. As far as the testing goes, we are at the mercy of the Chilean Nuclear Commission, their personnel, and equipment. Progress is being made, but without our own lab and equipment, it is impossible to set any scheduled milestones. As test results come back, we will keep everyone appropriately informed.

    If anyone has special talents, interest or equipment in the area of x-ray technology, and wants to help develop the x-ray capture device, we would love to have you pitch in and help. That’s what the Focus Fusion Society is all about.

    #2223
    AvatarLerner
    Participant

    Let me slightly correct that. Patent applications are now published 18 months after filing, whether or not the patent is issued, so everything will be public in six months’ time. Based on the USPO’s response time, it will probably take about two years from now, three years total, to actually get a patent.

    There is a trade off in photo-electric devices between expense per unit area and efficiency. A more complex, multilayered system will be more efficient, but more expensive per unit area. But if you have a source that has a very high power per unit area, you can afford a higher expense per unit area, but still have a low expense per unit power. The DPF will be producing x-rays at a rate of megawatts/meter squared, as compared with a kW per meter squared or less for sunlight. So we can afford to make a much more efficient converter.

    #2224
    AvatarTransmute
    Member

    Answer me this: is net useful energy possible without converting the x-rays? Can the decelerator alone produce enough energy to run the reactor and produce electricity? I have never heard of high efficiency x-ray photovoltaic.

    #2225
    AvatarDuke Leto
    Member

    Has there ever been any reason to make one transmute?

    #2226
    AvatarTransmute
    Member

    No, there has not, which bothers me greatly because new technologies (or at least untested ones) are likely to fail or have added complications. Added to the fact that DPF fusion is a untested technology, the need for efficient x-ray photovoltaics adds another level of improbability to the whole concept.

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