Z-pinch Sunspots

[BeAChooser]

Aren't they using magnetic "pinch" to create nuclear fusion ?

Isn't it interesting that the "pinch" is an EM phenomena ... not a gravity phenomena. And a phenomena the mainstream astrophysics community mostly ignores.

The sun is gravity-powered, when you think about it. It requires very large amounts of gas for the whole thing to work.

Gas?

 

[Ziggurat]

Really? Well that seems a little at odds with your very next statement:

Not at all. You just can't read. The part you didn't bold is the critical part. We cannot maintain solar core pressures by any means. None of your links contradicts that statement in any way, shape, or form.

Oh. I see. All these researchers are just being *sloppy* with their language:

https://www.llnl.gov/str/Hill.html "Much of the renewed interest in spheromaks is focused on a research effort at Lawrence Livermore called the Sustained Spheromak Physics Experiment (SSPX). ... snip ... According to SSPX leader David Hill, the tokamak concept is considered the leading contender to generate sustained fusion reactions".

What's sloppy about that? I see no indication that he's claiming to produce solar core pressures. So where's the contradiction between what he said and what I said? There is none.

http://news.bbc.co.uk/2/hi/science/nature/4328597.stm "Achieving stable and sustained reactions on Earth, however, present an immense challenge. The Iter design is for the reactions to take place inside a 100-million-degree gas (plasma) suspended in an intense doughnut-shaped magnetic field. Iter will consolidate all that has been learnt over many decades of study. It is expected to produce 500MW of fusion power during pulses of at least 400 seconds."

Once again, no mention of pressure. But there is a mention of a temperature. And low and behold, that temperature is higher than the expected solar core temperature of only about 14 million K. It needs to be higher preciesly because we cannot get the pressure anywhere near as high. Once again, no contradiction, merely your inability to figure out VERY basic ideas.

400 second long pulses? And you don't think that's "sustained", Ziggurat?

Tokamak reactors are indeed looking for sustained fusion. I never said they weren't. But they're looking at pressures much lower than solar core pressures - are you honestly so clueless you couldn't figure that out? It's Z-machines which are not sustained (but pulsed) that can produce ultra-high pressures.

Guess you'd better tell them it's NOT POSSIBLE and save us all some development costs.

Guess you better figure out how to pull your head out of your posterior.

 

[The Man]

Well then by now don't you think we should have free energy for all?

How would you define “free energy”, hydrodynamic, solar, geothermal, nuclear fission or even fusion? All of these come with requisite costs; these costs involve production, maintenance and delivery of that energy. Don’t forget that oil is just stored solar energy. “Free energy” is a misnomer; the best we can do is to minimize cost.

 

[The Man]

Fuel loading would be one the primary engineering aspects preventing continuously sustained fusion even if temperature and pressure could be continuously maintained (unless you happen to have 1.98 x10³⁰ kg of hydrogen handy). Direct Z-pinched fusion on the surface of the sun would be a pulsed reaction. Unless you maintain that the plasma remains sufficiently pinched while being fuel loaded.

This brings up the question as to what is the fuel source for direct Z-pinched fusion on or in the sun. In proton-proton cycle fusion the deuterium fuel is produced by an energy dependent (taking energy) weak nuclear interaction fusing protons into deuterium nuclei. In a modern hydrogen bomb lithium-deteuride is used as fuel (deteuride being basically deuterium) but also producing ⁴He and ³H (tritium) when exposing the ⁶Li to free neutrons (under those temperature and pressure conditions), giving a deuterium tritium fusion reaction. In all of the terrestrial laboratory fusion efforts, deuterium is also the primary fuel used, removing the energy reducing process of producing deuterium from protons. Mind you that the neutrino release only comes from the weak nuclear interaction (energy dependent) producing deuterium nuclei from two protons (by changing one of the protons into a neutron) and not from the energy releasing fusion of deuterium (or deuterium tritium) nuclei into helium nuclei.


http://hyperphysics.phy-astr.gsu.edu/Hbase/astro/procyc.html#c1

The carbon nitrogen oxygen cycle is the fusion considered to dominate in stars twice or more massive then our Sun

http://hyperphysics.phy-astr.gsu.edu/Hbase/astro/carbcyc.html#c1

For deuterium tritium fusion

http://hyperphysics.phy-astr.gsu.edu/Hbase/nucene/fusion.html#c1

For nuclear weapons

http://library.thinkquest.org/17940/texts/nuclear_weapons/nuclear_weapons.html

 

[BeAChooser]

The part you didn't bold is the critical part. We cannot maintain solar core pressures by any means. None of your links contradicts that statement in any way, shape, or form.

But I wasn't trying to contradict that statement. In fact, I never tried to contradict it. As long as we agree that the fusion community has indeed been trying to sustain a fusion reaction ... and haven't succeeded ... fine. Keep in mind that this whole conversation started because Reality Check claimed the sun essentially works like a long string of nuclear bombs going off one after the other. That's neither right nor is a string of nuclear bombs going off one after the other "sustained" in the sense that those trying to develop sustained fusion here on earth meant ... at least until very recently. Why you joined in to object when I pointed that out isn't clear.

By the way ... it looks like we wouldn't want to reproduce the fusion occurring in the sun anyway. http://en.wikipedia.org/wiki/Nuclear_fusion "At the temperatures and densities in stellar cores the rates of fusion reactions are notoriously slow. For example, at solar core temperature (T ~ 15*MK) and density (120*g/cm³), the energy release rate is only 276*mW/cm³—about a quarter of the volumetric rate at which a resting human body generates heat." That wouldn't make a very good power source for earthly use.

 

[BeAChooser]

How would you define “free energy”

I thought I put on a humor tag. Perhaps I should have used a sarcasm tag.

 

[The Man]

I thought I put on a humor tag. Perhaps I should have used a sarcasm tag.

Sorry, but your use of smilies is so replete that I never know what you really intend with them, so I have generally disregarded them. I apologize for my oversight.

 

[The Man]

By the way ... it looks like we wouldn't want to reproduce the fusion occurring in the sun anyway. http://en.wikipedia.org/wiki/Nuclear_fusion "At the temperatures and densities in stellar cores the rates of fusion reactions are notoriously slow. For example, at solar core temperature (T ~ 15*MK) and density (120*g/cm³), the energy release rate is only 276*mW/cm³—about a quarter of the volumetric rate at which a resting human body generates heat." That wouldn't make a very good power source for earthly use.

You neglected to post the rest of that quote supporting Zig’s assertions.

Thus, reproduction of stellar core conditions in a lab for nuclear fusion power production is completely impractical. Because nuclear reaction rates strongly depend on temperature (exp(−E/kT)), then in order to achieve reasonable rates of energy production in terrestrial fusion reactors 10–100 times higher temperatures (compared to stellar interiors) are required T ≈ 0.1–1.0 GK.

The difference being in the volume available (temperature, pressure and volume are related, with the additional caveat of number of molecules).

http://en.wikipedia.org/wiki/Sun#Core

About 3.4 × 10³⁸ protons (hydrogen nuclei) are converted into helium nuclei every second (out of ~8.9 × 10⁵⁶ total amount of free protons in the Sun), releasing energy at the matter–energy conversion rate of 4.26 million tonnes per second, 383 yottawatts (3.83 × 10²⁶ W) or 9.15 × 10¹⁰ megatons of TNT per second. This actually corresponds to a surprisingly low rate of energy production in the Sun's core—about 0.3 µW/cm³ (microwatts per cubic cm), or about 6 µW/kg of matter. For comparison, the human body produces heat at approximately the rate 1.2 W/kg, millions of times greater per unit mass. The use of plasma with similar parameters for energy production on Earth would be completely impractical—even a modest 1 GW fusion power plant would require about 170 billion tonnes of plasma occupying almost one cubic mile. Hence, terrestrial fusion reactors utilize far higher plasma temperatures than those in Sun's interior.

As a volumetric relationship it only says that the energy production per cubic meter of volume is very low. If you don’t want to do the math yourself, 3.83x10²⁶ watts divided by 3 x 10^-7 watts per cubic centimeter equals 1.23 x 10³³ cubic centimeters or 1.18 x 10⁶ times the volume of the earth. That’s an awful lot of bodies. Bamboozle yourself if you want, but don’t try to bamboozle us.

 

[Reality Check]

But I wasn't trying to contradict that statement. In fact, I never tried to contradict it. As long as we agree that the fusion community has indeed been trying to sustain a fusion reaction ... and haven't succeeded ... fine. Keep in mind that this whole conversation started because Reality Check claimed the sun essentially works like a long string of nuclear bombs going off one after the other. That's neither right nor is a string of nuclear bombs going off one after the other "sustained" in the sense that those trying to develop sustained fusion here on earth meant ... at least until very recently. Why you joined in to object when I pointed that out isn't clear.

BAC: Actually I did not claim this as literal fact. I noted that the fusion within the sun was analogous with (i.e. has a likeness to) the fusion in hydrogen bombs. Also that we know the parameters needed for solar fusion as well as we know the parameters needed for hydrogen bombs.

 

[Dancing David]

But I wasn't trying to contradict that statement. In fact, I never tried to contradict it. As long as we agree that the fusion community has indeed been trying to sustain a fusion reaction ... and haven't succeeded ... fine. Keep in mind that this whole conversation started because Reality Check claimed the sun essentially works like a long string of nuclear bombs going off one after the other. That's neither right nor is a string of nuclear bombs going off one after the other "sustained" in the sense that those trying to develop sustained fusion here on earth meant ... at least until very recently. Why you joined in to object when I pointed that out isn't clear.

By the way ... it looks like we wouldn't want to reproduce the fusion occurring in the sun anyway. http://en.wikipedia.org/wiki/Nuclear_fusion "At the temperatures and densities in stellar cores the rates of fusion reactions are notoriously slow. For example, at solar core temperature (T ~ 15*MK) and density (120*g/cm³), the energy release rate is only 276*mW/cm³—about a quarter of the volumetric rate at which a resting human body generates heat." That wouldn't make a very good power source for earthly use.

Appeal to emotions, is the potentialy fusing core of the sun the size of a human body?

 

[Belz...]

The sun isn't gas, technically, its nearly entirely plasma, which is a different state of matter all together from gas.

More-or-less. Doesn't change what I said.

 

[Belz...]

Isn't it interesting that the "pinch" is an EM phenomena ... not a gravity phenomena. And a phenomena the mainstream astrophysics community mostly ignores.

It's interesting you didn't spot how what I said contradicts what you said.

We're talking about labs, NOT the sun.

Gas?

Yeah, where plasma is a subset of gas under some definitions.

 

[Ziggurat]

But I wasn't trying to contradict that statement. In fact, I never tried to contradict it. As long as we agree that the fusion community has indeed been trying to sustain a fusion reaction ... and haven't succeeded ... fine.

Two problems with this claim. First off, magnetic confinement (ala Tokamak reactors) is the only method being pursued seriously which is a sustained reaction. Z-machines and laser implosion devices are not sustained. They would be pulsed.

Secondly, it's simply false that they haven't succeeded at producing sustained fusion. They have. The problem is not getting fusion, it's getting efficient fusion which can actually produce more power than it takes to run. That's the engineering challenge. But if you just want to get some fusion, hell, there are table top devices which can do that.

Keep in mind that this whole conversation started because Reality Check claimed the sun essentially works like a long string of nuclear bombs going off one after the other.

Analogies are frequently imperfect. The irony here is the frequent appeal to such analogies used by EU proponents in place of actual numerical models.

Why you joined in to object when I pointed that out isn't clear.

I jumped in because you seem to be under the impression that high temperatures and pressures like those found in the sun are not enough to sustain fusion reactions at the rate necessary to produce the power output of the sun. But they are. We cannot recreate such a process in a sustained manner on earth simply because we cannot sustain those pressures. Do you disagree with that?

 

[BeAChooser]

We cannot recreate such a process in a sustained manner on earth simply because we cannot sustain those pressures. Do you disagree with that?

No.

Do you agree that fusion may be occurring on the sun anywhere that z-pinch phenomena might be active?

 

[Ziggurat]

Do you agree that fusion may be occurring on the sun anywhere that z-pinch phenomena might be active?

I've got no reason to think the current densities are ever large enough to drive significant Z-pinching. Even if it were, I've got even less reason to think that it's going to contribute any significant fraction of the sun's power output. No, I'll take it a step further: I have reason to think that Z-pinch driven fusion CANNOT produce a significant fraction of the sun's power, because there's no strong feedback mechanism.