[delt0r]

Not what i was talking about. The reaction is p+11B-> 12C* -> 8Be*+alpha -> 3alpha +gamma. These gammas are below the 7MeV range IIRC. These gammas are quite rare (not that rare however, it is why the energy distribution of the resultant alphas are the way they are) but that does not change the fact that even .1W of gammas is a *lot*, and you are talking about 60MW or more, so even these quite small background levels are still on the order of kW and then you need a lot of shield to get than down to levels that are safe for humans to not worry about. Even the low level of background neutrons will matter at these power levels for something that is suppose to be flight weight.

The problem is that 1W out of 60MW is only much less than 1ppm, but still very bad for human health, and gammas are really hard to stop.

I am not claiming they are hard to deal with generally. I am claiming they are hard to deal with for something that needs to be flight weight. Power density in aircraft is critical.

[delt0r]

It is a easy calculation and you need a lot more than a meter for that kind of power. Even 1J on the outside is going to be a problem for passages on a 1+ hour flight, there are some quite high energy gammas (much higher than 1MeV). Its easy to deal with on the ground, not for flight. Gammas are a real PITA to shield against without some serious 1/r^2 “shielding” or in a pit etc. Water is not very good at dealing with gammas, dense materials do much better.

[delt0r]

There is another problem. A FF using p+11B reaction will produce some high energy gammas. About .1% of the energy output or so, ie about 6kW of gamma in the MeV range. Even if the rate is less by a factor of 10 that is still a lot of radiation. These will need far more than a 1 meter of shielding. Even a meter is too much for the weight of an aircraft.

I can’t see p+11B flying. It makes more sense to use a big power station to create jet fuel out of air and water.

[delt0r]

The Ecat suffers from everything cold fusion suffered from. No viable method of real fusion. There is a lot of data out there with fusion reactions. There is a lot of validated theory about the strong nuclear force and the structure of the nucleus. Yet for the Ecat to work is has to all be wrong. literally 1000s of experiments and mountains of data. Now you can get energy out of a reaction fusing hydrogen with nickle. But not without radiation, not without gamma rays and not with the well know decay chains that have been observed 1000 of times in previous experiments. Also there is a really really high coulomb barrier they claim is over come with a little heat. Add to that the high secrecy no details, it stinks of a scam. There are a few mitigating circumstances that perhaps indicate its not a scam but a mislead individual who is ignorant of what he is doing or even measuring. Hell even the successful test that measured ~400kW needed a 500kW generator running the whole time, but just for “warm up”, trust us. Yea right.

This is in stark contrast to Focus Fusion. Focus Fusion, if it works is a break through. But it does have a very legitimate base in theory *and* experimental data. And if it works there are going to gamma rays and some neutrons to deal with. Low levels but they will be there. Eric has said as much in his Google talk. He does not claim anything that goes against all that we do know and have experimental evidence for.

Yes there have been particle accelerator experiments for proton reaction for many materials. It is interesting for nucleoli-synthesis theory’s even if not for fusion.

You know what you get when you add a proton to 11B and then take away 2 Helium nucleus? Another Helium nucleus. You can’t change the number of protons+neutrons you have.

[delt0r]

If we only invested in things that already work, there would be no laser, transistor, generators etc. Before there was a “first car that moved slowly” there was a bunch of internal combustion engines that didn’t work at all. You just don’t remember them or care about them. But without that R&D there would be nothing to remember!

Did you know that one of the first internal combustion engines that was proposed used gun powder!

[delt0r]

Clearly diversity in funding is a much better idea. Many of the mainstream fusion folk have been making the same claim. Personally if we are serious about our energy future (and by future I mean >100 years) then some serious money should be put into energy and in particular nuclear (yea.. both fission and fusion–we want something that burns bombs 🙂 ).

Also the energy per neutron is a awful metric, I think beam target neutrons sources do much better for example, and IEC probably do better as well. Neither is going to lead real energy output.

[delt0r]

In ITERs defense, they kinda of need to build it first. The cost overruns to date have been from politics not the science delaying the construction so long (almost a decade). In fact that is perhaps the biggest problem with ITER, too many cooks in the kitchen, and some of these cooks are not scientists.

I know traditional fusion is a dirty word here, but if we are going to be talking about practical output you are going to have to acknowledge that these machines are getting the closest to breakeven than anything else (Lawsons criteria etc). When the tomakak was reviled by the Russians, it was 100x better than anything else, so good that the rest of the world did not believe them. It wasn’t until western scientists went and took their own measurements before they believed them. In the last 40 years confinement has improved as much as computer power has over the same time period.

Or perhaps by results you mean profit or some other metric (a working power station)? Be careful here, you may just give a metric that Focus Fusion does very poorly at, even worse than ITER and there kin.

[delt0r]

I think you have vastly underestimated the size of some projects. For example the Manhattan project. Remember that ITER is 10billion over 20 years, not each year. Fusion does not get that much in the bigger scheme of things.

[delt0r]

I don’t like doing the political bringer of doom, but the simple reason fusion gets low funding across the board is that coal and oil are cheap, and a few $M on “green” keeps the rest happy.

[delt0r]

The trick with cap lifetime is to downrate. By getting caps that are rated at 2x the used voltage you get lifetime multipliers on the order of 10000. This is too expensive for a experiment that may only do 5000 shots its whole life, but well within the capitol cost/running cost trade off of a commercial unit. You pay 5-10x more for the caps and get 10000x more lifetime (note that ESL is not a huge problem for DPF). The switching is perhaps the hardest bit, but by no means unprecedented. Thyratron fire many times per sec for radar applications and although there initial life times was measured in 1000 of pules modern units get a million or more (in some cases).

Sometime i think people forget what it costs to buy energy. Replacing 10 thousand dollar switches once a week will still be economic under many circumstances (yes bigger than 1MW–there is a reason power stations are as big as they are). My power and gas last year for just me was 1000EU.

We can even work it out. A 100MW plant produces 1.6 million dollars of energy per week at typical domestic rates (10c kWh). Remember even for traditional nuclear, fuel costs are negligible. Replacing things regularly that can be somewhat recycled can still work fine. Note that at 10Hz there are 315 million cycles in a year.

ps I forgot, you should look up self healing capacitors. Pretty cool. It is what the NIF is using.

[delt0r]

I see a lot of assertions and no math. In fact i see quite a bit of misunderstanding of fundamental plasma physics. The ion “scattering” cross section is generally defined as the 90Deg angle scattering. It is many many times higher than the fusion cross section, they do not stay confined. No matter what you do with one beam compared to another, it physically identical to having one set of ions stationary and the other colliding with them (your reference frame just moves with one beam–the results are always the same), in this case they just scatter, and your densities are way too low for any real fusion. Unless you have some uber magic accelerator. In which case light ion ICF is totally easy. We have not solved kink and sausage instability without a theta field and hence low beta limits*. There are many more things wrong with the physics sorry (Just asserting that XXX instability is not an issue does not cut it). Also the English needs work. Even the title does not make much sense.

It should be noted that Lerner has *not* swept any known plasma instability under the carpet. He has and continues to address every possible issue in this regard. This is why he gets publications out while a lot of the IEC crowed do not.

*There is shear stabilized z pinch. However there was only a few experiments so far, and only one with high currents. Oh and the so called advanced mode Tokamak which is also shear stabilized IIRC, but then there is these pesky ELM.

[delt0r]

No it wouldn’t. It would just cool and perhaps sputter some contaminants into the plasma, since they are moving so fast compared to any physically plausible vibration. From the plasmas point of view, the wall is stationary.

[delt0r]

The timescales of turbulence and cooling etc in plasma is measured in microseconds. Also these devices are huge. So there is no way this is feasible as you can’t move that much mass far enough to matter. Perhaps “vibrating” magnetic fields, or active feedback. Some work is being done with that now.

[delt0r]

The term supercomputer is not a good one anymore. Sure some would say i don’t have access to one. Yet our cluster has 500 cores and all have at least 4gig ram per core. The high mem nodes have 16gig per core. This is more powerful that supercomputers 10 years ago. The way here in the EU clusters are shared with departments and just asking for time. Getting time on a cluster would not be difficult or expensive. I am sure the US has similar programs. I am even allowed to put on “fun” code on when its empty (often enough).

In fact one of the main reasons you are seeing a lot more simulation work with ITER class devices is that computers are finally catching up to the details that are needed (aka neoclassical transport and ELM etc). Pinches are however harder to simulate since there are very large gradients in just about every parameter. Using Vlasov type equations (guiding center stuff) is not easy or IIRC even possible.

[delt0r]

Lets run numbers. We don’t have to guess in physics. Well not with everything.

Lets say we want 1W and assume we have 100% efficient fusion. Now lets also use the highest energy density fuel, DT fusion. We get 17.6MeV for a pair of atoms which is 2.8*10^-12 J. So for 1 W we need 7.2*10^11 atoms to fuse per second. In words that is 720 billion atoms per second. Millions will only produce mW to mu W.

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