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Chat is one of those things that needs a critical mass before it gets flowing; i reckon when 100 people hang out there routinely, it’ll have some traffic

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miller-urey experiment however did not include anything close to a complete list of elements. conspicuously missing are phosphorus, magnesium, calcium, and many others.

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some thoughts and calculations lead me to believe that
(a) the exit pulse is probably on the order of 10 ns;
(b) the inductance of the coil should be about 30 uH overall;
(c) the rogowski coil should use superconducting YBCO tape in a liquid N2 bath. each 1cm wide YBCO wire can support 300 A current; (though i have not yet made allowance for the magnetic field)
(d) transducer diameter is 3 m, coil inner diameter is 0.955 m, outer diameter is 6.955 m;

this alters the design to 2.22 MV and 75 kA for 10 ns, or 250 coils of 5 turns each, in parallel. (total 1250 turns).

i expect efficiency to be above 88%, so long as the coils are tightly coupled magnetically (> 0.999), and the parallel capacitance is below 20 pF.

the following image shows what the coil will look like with about 1/3 of its windings on: http://qikr.co/files/pics/r/rogowski4065981.png

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let’s just say, *if* the exit beam pulse were 1 ns long, and the coil’s transducer diameter is on the order of one wavelength, that’s 30 cm; for a 5 MW reactor producing 3000 pulses per second, we’re asking for 1.66 kilojoules per pulse; this is about 12.9 MV and 129 kA, for 1 ns.

the more turns of coil, the higher the voltage but the lower the current, and they are inversely related. so if you want high voltage from this, then you’d have lots of turns and a narrower gauge wire; but lower voltage would imply fewer turns and larger gauge wire. you want to minimize the resistance of the coil and the inter-turn capacitance, and there is a skin effect to consider, as a 1 ns pulse can penetrate only 2 micrometers into copper. effective resistance on ordinary awg 10 copper wire (2.6 mm dia) would be 1 ohm / m. (losses are I^2R, so to get these below 10% we need R < .01 ohm/m. i think that makes a good argument for superconducting wire. but there are other problems: critical current density of YBCO is high, but in thin films this yields nominal 300 A/cm width of tape, causing us to increase tape width or number of layers, which increases inter-loop capacitance. see http://www.ornl.gov/sci/oetd/documents/aug04_intro.pdf for more on this.)

let’s imagine there are 1000 turns of the above size; each turn would be collecting 40.8 kV and running 40.8 kA current, for each 1 ns pulse. i expect dielectric strength of the chamber gases at 40 torr to be greater than those at atmospheric pressure, but if not, then each turn would need to be over 2 cm apart at closest point. this implies 6.4 m inner diameter. outer diameter is then 7.0 m. this coil’s inductance is 5.38 mH.

at 10x the dielectric strength, the inner diameter could be 1.6 m, outer diameter 2.2 m; this coil’s inductance is 19.1 mH.

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found this interesting composite material, containing barium titanate nanoparticles, coated in a plastic.
http://apl.aip.org/resource/1/applab/v95/i13/p132904_s1

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benf wrote: Sorry link didn’t direct properly, see edit in previous post 🙂

link doesnt work for me; try compressing it with tinyurl.com

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oldjar wrote:
It’s not true that … It’s probably closer to ….

okay, let’s make this a real pissing contest by showing references. i’ll slam yours, you slam mine.

http://www.globalresearch.ca/new-book-concludes-chernobyl-death-toll-985-000-mostly-from-cancer/20908

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This reaction is as follows:

198Hg (9.7% abundance) –> 197Hg + n; 197Hg (electron capture h.l. 64 h) –> 197Au

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but if you do knock neutrons out of mercury, then sometimes you will get gold

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zapkitty wrote: … just the PTB placing a marker in the race for “dirty” fusion?

You’re not imagining things insofar as it was a bombshell which shed surprisingly little light for all the noise it’s caused.

well, this noise should help to place tokamak on the back burner where it belongs; maybe to the benefit of all alternative fusion schemes?

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oldjar wrote:
There is no waste problem with fission. All the high level waste can fit inside a football field that is only about 10 meters deep. The low level waste is safe in about 50 years, and much of the low level waste isn’t even radioactive. This is the shorter than the timeframe of mainstream fusion designs, and is much less radioactive during that timeframe. Besides, the transuranics produced from fission reactors can be very useful once we find better ways to separate them. Fission products are easy enough to dispose of, but why dispose of them when they can be useful in the future? The radiation being detected by Fukishima in “Far-flung places” is less than 1% of background radiation. Levels that are 100X background radiation levels are completely safe to humans. Background radiation levels in certain places of the world are over a 100X background in U.S., and they have lower cancer rates.

Chernobyl remains among the top ten most polluted places on this earth. I invite you to live there.

But you know, maybe the region would make a good place to store fission wastes long-term?

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force from thrust will balance drag, so really what matters is the top speed. at high mach numbers, air heats up enormously due to shock.. it even ionizes. the solution, for space planes, is to fly higher.

skylon is designed to fly at 26 km altitude, where air is rarefied to around 3.5% of normal atmosphere

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ikanreed wrote: Dumb idea: what about filling the chamber with cold gas and using infrared cameras to spot the leak? Is that too much risk to the system?

why use cold gas? why not gas at the normal operating temperature?

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yes, we should be thinking in terms of that much heat.

although conversion of alpha exit beam is potentially very efficient, (> 80%), the overall system efficiency is close to 50% if i recall correctly from figures Eric gave.

So a reactor capable of 5 MW of useful work will probably generate 5 MW of waste heat as well; and if you can boost the system efficiency, then you can increase the useful work while holding the waste-heat about the same.

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i had previously estimated amount of helium used for primary coolant, to be about 2 kg/s flow past the hot tip
in order to draw away 5 MW of heat. maybe that’s not liquid, but it is compressed a lot.

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