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Re: Why is ignition required for a fusion power plant

Posted: Sat Nov 15, 2014 11:35 pm
by Chris Bradley
FWIW, no need to have a power source of that magnitude for the crank-start. JET cranks its tokamak up by a couple of huge inertia wheels that it spins up over several minutes from mains electricity, then dumps that energy quickly.

Re: Why is ignition required for a fusion power plant

Posted: Sun Nov 16, 2014 2:15 am
by Dan Tibbets
Bob Reite wrote:Once you get the hypothetical 800 MW (electrical) fusion reactor started with the 200 MWe coal plant, what's to stop you from diverting 200 MW from the fusion reactor to sustain the reaction, leaving a net output of 600 MW electrical?
Nothing.

The initiating energy could come from some on site power source or the grid. It is much like a car engine. It doesn't work without a spark plug and a starter. But once running the battery is not needed if you have an alternator, and the starter is out of the loop. An ignition machine might be compared to a diesel, no spark plug is mandatory. A gasoline engine does require the spark. Poor analogies as once ignited the fuel is hot enough to continue burning, only the initiating sequence is different. A jet engine or external combustion engine has been compared to the amplifier view of IEC. The air is compressed, heated, then fuel is added and it burns, producing excess energy. A portion of the hot jet energy is harvested by the turbine, which runs the compressor....

Jets need some type of startup input, but once running they power themselves. They are not ignition machines though, as just adding more fuel does not maintain useful burning. Umm... ignore the afterburner :) . The compressor is a key input that has to be supported. Further detailing starts to unravel the comparisons.

Dan Tibbets

Re: Why is ignition required for a fusion power plant

Posted: Sun Nov 16, 2014 5:36 pm
by Richard Hull
Thus far none of this has happened. Not one watt of electrical energy has ever been harvested from any of the fusion greats, like JET or any tokomak. They talk about near or over unity when megawatts are expended to run their toys, but not one watt was ever turned into electricity that powered anything. the earliest fission attempts produced converted electrical power within 3 years of the dropping of the atom bomb. and distributing it to power submarines within 10 years. and the public in 12 years after bomb drop. It is now 50 years since the first fusion bomb was detonated and not one watt of electrical energy.

Richard Hull