[JimmyT]

Opps, Forgive me, Transmute, for not reading from the top post down in one setting. I forgot the train of thought. I mistakenly thought that this thread was advocating the use of DPF produced neutrons for these other uses even if it totally works as a power reactor. I understand the thread now. It seems reasonable now.

[JimmyT]

I should have said “cheaply harvested energy”. Sure, neutron’s energy can be dissipated in some medium whose heat is then used to make steam to run a turbine to run a generator. But there goes your costs up to $1,000 per kw just like a conventional power plant. It defeats the economic advantages ofDPF to begin with. Again, like I said, unless you want to use the neutrons for transmutation.

[JimmyT]

Damm! I wanted one of those wrist watches.

By the way, though. Any time you are talking about reducing shielding thickness in a roughly spherical device you have to cube that factor to get the reduction in mass and volume. So, 0ne-sixth cubed is 1/216th of the mass and volume.

I think most of the shielding in a hydrogen-boron DPF is for protection from the side reaction neutrons. Not the x-rays. The fusion reaction Helium-3 + Hydrogen is actually more correctly stated as Helium-3 + Deuterium which yields Helium-4 (which is an alpha particle) and a Proton.
The side reaction Deuterium + Deuterium sometimes produces tritium and a proton, and sometimes produces helium-3 and a neutron. A fairly high energy one at that. I haven’t seen the statistical frequency of these side reactions. But I haven’t looked that hard for them either.

So I’m not sure about the actual 1/6th reduction in shielding thickness. Might not be do-able.

I don’t know how to use the quote thing. Could one of you guys direct me on where to go for instructions on that?

[JimmyT]

Actually a lot of the development and testing work on focus fusion will be done using hydrogen or deuterium. This is one way to measure the “success” of the fusion reaction. By measuring the number of neutrons produced. Somewhere in the development plan Eric outlines this rather concisely. You will find it on LPP’s website.

[JimmyT]

Well, since x-ray emissions are proportional to the square of the nuclear charge. It would be 4/25 of the emissions with boron, or about one sixth.
I am pretty sure that this reaction has a significantly lower ignition temperature than hydrogen-boron too.

[JimmyT]

Minimal size does seem to be about semi-trailer size. This is when you include the necessary shielding, support equipment etc.
So, no autos or motorbikes runing on dense plasma focus. Probably a locomotive is about the smallest device to be powered by them. …….. Or is it?

So far we have only been considering DPF’s burning hydrogen and boron. I wonder if a DPF burning Helium-3 and hydrogen truely might be coffee can size? It is an aneutronic reaction.

I know. I know. Helium-3 doesn’t exist on earth. But if space really does open up due to the availability of Hydrogen Boron DPF; Then maybe moon harvested Helium-3 is a possibility. Great miles per gallon.

Any of you fellow geeks want to take a stab at this one?

[JimmyT]

Keep in mind that the radiation hazard is only one of the reasons for wanting to avoid neutron production. The energy from charged particles in a beam is easy to harvest. Any neutrons produced would carry away energy too. But the only way to harvest it would be by some sort of heat engine. Now if you are wanting to produce neutrons for some transmutation process, fine. But keep in mind you are going to sacrifice harvestable energy in the process.

[JimmyT]

With regards to waste heat:

The overall process is estimated to be around 42% efficient. That means that a 10 megawatt power plant will produce 17 megawatts of waste heat. It would be a shame not to make the most of this resource.

The very high efficiency (80% to 90%) are related to converting the x-rays and alpha particle beam to electricity. The conversion efficiency of the input pulse to that plasma ball where the fusion takes place is a bit of a question mark at this point.
Up to now this step in the process has not been very efficient and is where a lot of electricity gets turned into heat. This is why cooling that central electrode is such a big deal.

Hopefully the trick that Aaron Blake proposed of introducing an external magnetic field will make this step very efficient too. We just don’t know. This is precisely why these extensive simulations are being done; in order to optimize this step.

[JimmyT]

Looks to me like we agree on virtually everything.

I’ve read every issue of Scientific American for the last 40 years.

The only thing I disagree with in the above thread is the environment of hysteria and despair.

And yes, I think there is considerable room for debate as to the validity of man made global warming. Unfortunately it has become a political issue not a scientific one. One ruled by political correctness and whines of consensus.

The ice caps are melting on Mars too.

[JimmyT]

The world is NOT running out of oil! Not anywhere close. But it is running out of cheap oil. In the past oil has been available at a lift price ( the price to pump it out of the ground) of 50 cents a barrel (in Saudi-Arabia) to $15 a barrel for north sea crude. Much oil is available at somewhat higher prices. Proof of this is the recent “discovery” of deposits in North and South Dakota and of an oil field off the coast of Brazil. Both of these deposits have been know about for some time (in the case of the Dakota fields about 30 years). But both the technology to exploit them, as well as the economics of exploiting them has been abscent.

Synthetic oil can also be produced from coal as the Germans did in WWII and the South Africans have been doing for decades. The process is called the Fischer-Tropsch process and oil can be thus produced for around $20 to $30 a barrel. Feedstock can be anything from coal to organic matter.

Focus fusion can dramatically reduce our use of this more expensive oil, and thus both reduce its cost (from a supply and demand perspective) and render its higher cost much less relevant to our economy.

[JimmyT]

Carbon isn’t the only reducing agent that can be used in the reaction to produce iron, and then steel, from iron ore. Hydrogen can do the same thing. And hydrogen can be readily produced anytime you have ample cheap electricty.

[JimmyT]

A better initial placement of the power units would be wherever there currently exists an electrical substation. Eventually the power plant feeding the substation, the transmission lines to the substation, and the substation itself could thus be eliminated. These (the substations) are already wired to the customers. It’s not uncommon for long distance transmission lines to loose 50% of the power they transmit. And they are very expensive to maintain as well as being somewhat controversial from a safety standpoint.
Higher cancer rates have been documented for those who live near long distance high voltage power lines. I personally think this is due to the indiscriminate use of herbicides to keep the vegetation down surrounding them, and not due to any electromagnetic effect.

One benefit of having mutiple small power stations as opposed to one mega- power station is that it makes it easier to use the waste heat for some useful purpose.
This is nothing new, I know. Con-Edison already uses waste heat to heat many (most?) of Manhatan’s buildings. Probably much the same is done in all northern US cities. Perhaps someone out there has first hand knowlege of this? I’m talking mostly out of my wrong oraface on this topic.

[JimmyT]

I have kinda been wondering to what extent the pulse rate of the reactors hooked up to the power grid could be varied. A lower pulse rate could result in cooler electrodes and less frequent maintaince. The trade off is, of course, lower power production. But the pulse rate could be increased to the nominal maximam only for the short time daily needed to meet peak grid demand. In other words: should the pulse rate necessarly be regarded as a constant?

[JimmyT]

Fenn, you are right about the center electrode containing berellium. But the reason is that berellium is transparent to x-rays. Which cromrises about 40% of the energy output of each pulse. We wouldn’t be able to capture the x-rays and convert them to electricty if they are absorbed by the electrode.

[JimmyT]

I like your Keltic icon, by the way.

According to Herr Lerner these power plants would use about 1kg/year. Probably more than that would be on hand. But not much more.

I personally think that my neighbor’s barbecue grill propane tank is potentially more dangerous.

Probably my car’s gasoline tank too, come to think of it.

[Author]

Posts