starts with vacuum theroy, am i looking at it wrong, or just a unique veiw.

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Carl Willis
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Re: starts with vacuum theroy, am i looking at it wrong, or just a unique veiw.

Post by Carl Willis » Wed Jan 09, 2013 12:57 am

So hobby fusion is not on track to "break even." Not exactly news.

Is that sad? Perhaps--in the same way that the finiteness of the human lifespan is sad. But we all know that just because you won't live forever doesn't mean you can't have a rewarding and contributory existence. Hobby fusion is educational, helping people understand the problems of fusion energy and become experienced with the techniques of research in this area. It leads young people into careers where they will get to work on the massive, international projects that are realistically aimed at "breaking even." And fusion is certainly not just about energy; it's behind electronic neutron generators and some isotope production schemes.

Reality has handed us a world in which fusion is harder than rubbing two sticks together. Let's not bewail the sadness of that against fantasy alternatives. Instead, we just need to calibrate our sense of what is possible and what is interesting to do with what we have.

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Re: starts with vacuum theroy, am i looking at it wrong, or just a unique veiw.

Post by Dan Tibbets » Wed Jan 09, 2013 7:34 am

Vacuum crushing something? As described, vacuum does not do this. If you are thinking of a can being 'crushed' as a vacuum is applied, what is really happening is air pressure outside the can isdoing the crushing.

As for placing two deuterons close together, that is the right idea, but it does not revel how you got them there. Once close enough two deuterium nuclei will fuse together due to the Strong force, but they need to be very very close together. As they approach this range they are increasing repelled away from each other due to the positive charges on the protons. The only way to get them to come close to each other is to throw them- accelerate them to some high speed.

Consider two magnets. Once close enough together they will stick. Imagine one glued to the ceiling(a very high ceiling), the other on the floor. Nothing happens. This could be considered as the normal separation of protons in everyday things. You have to throw the floor magnet hard enough that gravity does not cause it to fall back to the floor, but instead reaches the other magnet and sticks. A certain speed had to be added to the floor magnet for the reaction to reach completion. The electromagnetic repulsion of two positively charged nuclei is the same principle. They do not want to get together until some threshold is passed. It is a balance between competing forces, and in nature protons that are not already bound up in a common nucleus will not approach each other unless some externally applied force changes things. The amounts of force needed are well know and it is considerable. You could squeeze the protons together, but how? No press is strong enough by a huge factor. It is far easier to just throw one proton towards another with sufficient speed so that it doesn't completely stop despite the repulsion till the sticking can occur. The speeds needed for deuterium fusion is over about 100 KM per second. That would be about 240,000 miles per hour.

If you want to consider some of the physics of massive objects like Neutron stars the crushing idea becomes relevant, but for us and normal stars, it is all about speed, speed, speed. (speed = temperature).

It is lucky that fusion is so difficult, otherwise we would not be here. Stars would burn up in a matter of days, or more likely never form as we know them. The Universe would be a far different place .

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Re: starts with vacuum theroy, am i looking at it wrong, or just a unique veiw.

Post by electron » Thu Jan 10, 2013 8:48 am

Hey chris,

Can u take the time to sort out and answer some puzzling questions!

First question, wouldn't the negative dc inner grid produce a magnetic field?
I guess the same would apply to the outer grid- it too would produce a magnetic field?

I'm asking cause I'm confused.

A example of my frustration would be if a negative electron was under acceleration , I say it would produce a magnetic field and wouldn't that magnetic feild be affected be the inner grids magnetic field.?

I under the impression a stationary electron has a negative electric field and no magnetic field.

James...

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Re: starts with vacuum theroy, am i looking at it wrong, or just a unique veiw.

Post by Richard Hull » Thu Jan 10, 2013 3:19 pm

The electron does have a magnetic moment and responds to a magnetic field.

A grid has no appreciable magnetic field even though it is a current carrier and has current flowing through it.

Again, read up on and know your physics. Current drives a magnetic field in any conductor via "amp-turns" simple fusors have only a few thousandths of one amp flowing in them and are acting as a single turn only. So the net field around the grid wire would be on the order of .01 gauss or so. Actually the magnetic field at any wire in the grid would be far less than this as the current carriers are arriving all over the grid and traveling through a complex network of interconnected wires. Only the grid stalk wire to the insulator would have the full current and .01 gauss field No electron turning magnetic energy here.

Also, you are not to change a thread's title in its flow, even if it is you own thread. So, I have changed them back. If you get a wild hair to change a thread's title in mid-stream, create your own totally new thread.

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Re: starts with vacuum theroy, am i looking at it wrong, or

Post by Michael R Cole » Thu Apr 10, 2014 6:28 pm

What I was reading somewhere was that in a practical fusor ( for a power plant ) the confinement grid would be on the order of 20 to 100 feet in diameter.

A lot of you have only done a fusor grid the size of a golf ball. I dare somebody to build a fusor grid say the size of a basketball inside of a 10 foot diameter chamber or even a grid the size of a softball inside a 2 foot diameter chamber. The volume of the plasma goes up by the cube of the size and the surface area only goes up by the power of 2.

Compare the ration of surface area to volume of a golf ball and then a softball and then a basketball. I don't have the money to build it unless I win nthe lottery or meet somebody who is building one anyways and needs an industrial electrician/EE to help make it work.

This is similar to how smaller mammals and birds have problems retaining body heat and large animals have problems getting rid of body heat.

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Re: starts with vacuum theroy, am i looking at it wrong, or

Post by Chris Bradley » Thu Apr 10, 2014 9:02 pm

Michael R Cole wrote:What I was reading somewhere
With such a clear reference to an authoritative archival work as this, who could doubt it? :facepalm:
Michael R Cole wrote:was that in a practical fusor ( for a power plant ) the confinement grid would be on the order of 20 to 100 feet in diameter.
On the contrary, making a fusor bigger could only aggravate the losses and reduce the achievable acceleration voltage.

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Re: starts with vacuum theroy, am i looking at it wrong, or

Post by Richard Hull » Fri Apr 11, 2014 5:58 am

The concept of a fusor as a power source is ludicrous beyond any hope of redemption to a meaningful discussion. Any fusion device, as currently produced, if made bigger, has no scintific basis for assuming it will be better. It would just be bigger and cost more and still be an epic fail.

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Re: starts with vacuum theroy, am i looking at it wrong, or

Post by John Futter » Fri Apr 11, 2014 8:00 am

Pity electron can not read the rules and at least get his log on name as a real person
yes you may have given it in a post but the username is still blank
and I do not know many people with the only name of electron

this should be fixed before more posting

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Re: starts with vacuum theroy, am i looking at it wrong, or

Post by Dennis P Brown » Wed Apr 16, 2014 12:41 pm

I am at a loss here, too - why answers questions to someone who grossly ignores post after post to have their real name displayed? This person joined in 2012 and they have no real name displayed? Maybe answer a question to a true newbie with a warning to add their real name but someone who has been here well over a year?

Policies are irrelevant if not followed by those who are primary posters here. I'd think people would follow the rule if it was enforced better (again, true newbies should get some slack, for a post or two.)

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Re: starts with vacuum theroy, am i looking at it wrong, or

Post by Werner Engel » Sat Apr 26, 2014 10:24 am

James, don't be sad - it took me at least two years of reading plasma physic books, publications (to be found for free in arxiv.org) and handbooks (like pfeiffer vacuum handbook) to get an idea of the knowhow needed to build anything close to a fusion device.
After talking to a researcher from the Tokamak device in Garching and following the theory behind ITER - I almost stopped my interest. It seemed waaayyy to complex for me.

But people like the ones in this forum make me think that I should go on with this very strange Hobby ;-)

Good luck,
Werner

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