Fusion and particle accelerator

[Jacques]

Does fusion have been observe in accelerator collision ?

If I collide protons with enought energy will they fuse ?

If yes wouldn't it take less energy than trying to confine a plasma to high temperatur ?

[thedarkshade]

To happen fusion a very very good deal of energy is needed. In CRTs temperatures have peaked 100 million C, and I don't know it that's enough hot for fusion. Sometimes even the nucleus of sun isn't hot enough to fuse, simply because the needed temperature is extremly hot!

[swansont]

Yes, you can get fusion with an accelerator. It takes a tremendous amount of energy — nowhere near break-even.

[thedarkshade]

I've heard that hydrogen bombs need more than 100 million C, since the explosion is supposed to take place in a millionth of a second. Is that true?

[Jacques]

It takes a tremendous amount of energy

How much ?

You need to overcome the protons repulsion up to the distance where the nuclear force is greater than the electrostatic force.

I don't know the math but Wiki

Using deuterium-tritium fuel, the resulting energy barrier is about 0.01 MeV.

It is not that much when we think that the top accerator are in the range of TeV.

If the energy to initiate the reaction comes from accelerating one of the nuclei, the process is called beam-target fusion; if both nuclei are accelerated, it is beam-beam fusion. If the nuclei are part of a plasma near thermal equilibrium, one speaks of thermonuclear fusion.

They tell nothing more about beam-beam fusion...

The reaction cross section σ is a measure of the probability of a fusion reaction as a function of the relative velocity of the two reactant nuclei.

That is where I am getting lost... Does the cross section of beam-beam fusion too small to give subtantial output ? Can we use a magnetic field to pinch the two beam to increase the cross section ?

Thanks

[Mr Skeptic]

The problem is that accelerators are designed to, well, accelerate particles, rather than, say, to be energy efficient. They accelerate very few particles to ridiculous speeds, but the energy that they consume is tremendous. Why would you think that we would be better off doing fusion in an accelerator than in a devise specifically designed for fusion for energy?

[Jacques]

Why would you think that we would be better off doing fusion in an accelerator than in a devise specifically designed for fusion for energy?

More like designing a fusion device using accelerator technology.

Why ?

Because with thermofusion the temperature needed is very hight because the particles energy is randomly distributed. The beam-beam fusion would not necessitate hard to confine plasma.

I did a little google and found that:

Colliding Beam Fusion Reactor

I am not the first to think about that ! But searching more I found:

Feasibility of a Colliding Beam Fusion Reactor

The first article give a Q of 2.7 but the other a Q of .02

[swansont]

It's also a matter of system capacity, as Mr Skeptic notes.

 

I recall the proton beam at TRIUMF was measured at roughly a microamp, and later they did 10 microamps with a new target facility (I think that was limited by what the target could withstand, but is probably order-of-magnitude for the system capacity).

 

That gives a power output of 10 Watts per MeV of reaction, assuming all protons interact. I assure you the operating power draw exceeded that by several orders of magnitude. You need a system designed for much higher capacity, that gives multiple opportunities for an interaction.

[DrP]

When I was at school I used to want to grow up and solve the worlds energy problems by sorting out the problems with nuclear fussion..... ahhhh.. if only.

 

A few years ago (late 90's) I had breakfast in a B&B near Didcot and got talking to some random bloke who was staying in the place. He worked at JET (the Joint European Torus) - I told him how interesting I thought the place was and that I'd heard they actually got to break even point (something quite superficial in the news was published that day and broadcasters didn't think that the worlds first fussion experiment to break even was as important as what colour dress princess Di was wearing that day - neadless to say it didn't get reported!). He told me that they actually had it up and running beyond break even for a few mins after that.

 

It's such a shame we haven't moved faster in progressing towards a solution - I know the research is expensive but what a beutiful ideal fussion is if we can get it sorted. Star power for the world - no more energy problems for ever. I hope the powers at be plough the money thats needed into the right areas to get this done - I'd love to see it in my lifetime. Then we can stop using up all the oil.

[Jacques]

But the more I read the more I am concerned about the environment impact of the fussion technology. We were told that fusion doesn't produce radioactive waste, that the only product is helium an inert gas...

But reading about the reaction, there is these fast neutrons that can contaminate the machine. How much secondary radioactivity will be produced ? Why no research on cleaner fuel like the p-Boron reaction ?

 

From post #7

Colliding Beam Fusion Reactor

I am not the first to think about that ! But searching more I found:

Feasibility of a Colliding Beam Fusion Reactor

The first article give a Q of 2.7 but the other a Q of .02

 

Of these two articles, what estimate of Q is the good one.

[insane_alien]

1 there is research on the p-boron reaction but it will require considerable experience with D-T fusion first.

 

also, the secondary nuclear waste will be short lived. we're talking a couple of decades to get back down to safe levels. 200 years tops. and even less than is produced by nuclear fission. maybe only a couple of tonnes per decade per reactor.

 

Q of 0.02 is closer but still a bit high.

[Jacques]

That reconfort me !

 

Q of 0.02 is closer but still a bit high.

On what do you base that ?

[insane_alien]

fusion energy does produce a lot of energy per gram of fuel but particle accelerators(as we currently know them) need to be huge power sucking monsters to get close to a decent mass flowrate. not to mention the confinement will be less than ideal and only provide one chance for fusion per particle.

[Jacques]

To overcome the energy barrier in let say p-Boron is

The reactivity has a broad peak if the energy of the proton relative to 11B is 580 ± 140 keV.

Am I right if I say that to accelerate a proton to an energy of 580 keV you need to have 580 kVolt potential ?

[insane_alien]

you'll need more than that as the boron will not be completely stripped of electrons and there are neutrons on board. you would need a couple of MV at least. but particle accelerators tend to use magnetic fields anyway.

[Jacques]

I was thinking of using a fixed target of boron so no need to strip any electron from boron. So I repeat:

Am I right if I say that to accelerate a proton to an energy of 580 keV you need to have 580 kVolt potential ?

 

particle accelerators tend to use magnetic fields anyway

Magnetic fields are used to curve the path of particle and use up a lot of energy. For the acceleration an electric field is used. And my question is about a kind of linear accelerator.

 

The big problem in current fusion experiment is the high temperature which necessitate the use of magnetic field for confinement. I am trying to figure a way to get fusion without the high temperature. I imagine that having particle with the proper energy would not create these high temperature if the reaction is spreadout on a larger surface.

Description of the reactor:

A source of ionized hydrogen (proton) injected in the center of a vacuum chamber a few meter in diameter. The potential between the center and the wall of the chamber is around 1 MV. A sheet of boron near the wall react with the accelerated proton.

A lot of little fussion will occured at the surface of the boron. The reaction happen in a continuous way over a large area, so no high temperature generated.

Do it make some sense ?

Thanks

[Mr Skeptic]

I was thinking of using a fixed target of boron so no need to strip any electron from boron. So I repeat:

 

 

 

Magnetic fields are used to curve the path of particle and use up a lot of energy. For the acceleration an electric field is used. And my question is about a kind of linear accelerator.

 

The big problem in current fusion experiment is the high temperature which necessitate the use of magnetic field for confinement. I am trying to figure a way to get fusion without the high temperature. I imagine that having particle with the proper energy would not create these high temperature if the reaction is spreadout on a larger surface.

Description of the reactor:

A source of ionized hydrogen (proton) injected in the center of a vacuum chamber a few meter in diameter. The potential between the center and the wall of the chamber is around 1 MV. A sheet of boron near the wall react with the accelerated proton.

A lot of little fussion will occured at the surface of the boron. The reaction happen in a continuous way over a large area, so no high temperature generated.

Do it make some sense ?

Thanks

 

They actually do do some fusion in a similar manner. They use a pyroelectric crystal to generate the insane electric fields needed. Read up on pyroelectric_fusion. However, it is rather inefficient but is used as a portable neutron source.

[Jacques]

Yes a similar manner ! Thanks for the link.

I don't understand why they use pyroelectric cristal to get the potential... Must not be a very effetive way to get potential. Why not use a simple tranformer ?

Thanks for your answer

[Roger]

1 there is research on the p-boron reaction but it will require considerable experience with D-T fusion first.

 

also, the secondary nuclear waste will be short lived.

 

Polywell fusion uses DD fuels, hopefully soon to be PB-11.

 

 

Heres a slightly inaccurate picture.

 

But the more I read the more I am concerned about the environment impact of the fussion technology. We were told that fusion doesn't produce radioactive waste, that the only product is helium an inert gas...

 

The fuel you fuse dictates what the products will be. PB-11 Fusion would be aneutronic but create radioactivity, Dueterium fusion creates lots of neutrons but no fission style radioatctivity.

 

Does fusion have been observe in accelerator collision ?

Yes.

If I collide protons with enought energy will they fuse ?

Yes

If yes wouldn't it take less energy than trying to confine a plasma to high temperatur ?

Very likely.

 

Dr Gerald Kulcinski of the U of Wis and Apollo Astronaut Harrison Schmidt are 2 big advocates of He fusion. Kulcinski uses Inertial Electrostatic Confinement to fuse He.

 

 

Kulcinski and his IEC fusion device.

 

 

In operation.

 

 

 

Meanwhile the late DR Bussard had developed his Polywell Fusion device, and completed Dueterium fusion test runs before his recent death. His work contines under DR Nebel, formerly of Livermore. Polywell may be able to fuse Boron11, using the Proton, Boron collision.

 

Dueterium and Tritium fusion creates neutrons, which degrade the materials in the fusion reactor and can hurt humans.

 

IIRC He and Boron are aneutronic fusion, no, or nearly no neutrons. Therein lies the advantages of these 2 fuels.

 

 

 

Dr Bussards WB-6 Polywell in operation in 2005.

 

Polywell fusion relies on accelerating 2 particles fast enough, so that when they collide, they fuse. Heres a brief

showing electrons forming a potential well inside the magnetic grid ( McGrid). Ions are introduced inside the MCGrid, they see the potential well and are attracted to it, at high speed.

 

Dr Nebel. formerly of Livermore, is running the current Polywell program in Santa Fe, Recently his WB-7 device saw 1st plasma. A device the same size, but more powerful, would be capable of test runs generating 50Kev to 65Kev acceleration, where the PB-11 fusion can occur.

 

Boron 11 fusion would create lots of alpha particles, which would be directly converted to electricity via electrostatic grids.

 

Theory says a 500MW PB-11 net power reactor core would be 3 meters across.

[Jacques]

Thanks Roger very interesting!

My first idea was more the reverse and more of a beam-target configuration. The ion are injected in the center and accelerated outwardly and colliding into a wall of solid boron...

I need to confirm some point before eleborating more on that.

1- What is the probability that a H+ ion accelerated to 580 keV hitting a solid boron piece fuse (do the fusion) ?

2- Is it possible to create an electric potential between the center of a sphere and its inside surface? Like having +500 kV at the center and 0 V at the inside surface .

Thanks

[Mr Skeptic]

2- Is it possible to create an electric potential between the center of a sphere and its inside surface? Like having +500 kV at the center and 0 V at the inside surface .

Thanks

 

Not if you want the sphere to be hollow. The effects of the other charges on the sphere's surface cancel each other outside the sphere, making it as if the sphere wasn't there if you are inside it. You'd have to have the charge at the center, but how would you hold it in place?

[Jacques]

You'd have to have the charge at the center, but how would you hold it in place?

Something like this

[Roger]

I need to confirm some point before eleborating more on that.

1- What is the probability that a H+ ion accelerated to 580 keV hitting a solid boron piece fuse (do the fusion) ?

I dont know.

I do know that theory says a proton and a B11 need 50 to 65 KeV acceleration to fuse. I'm guessing that 580 KeV is enough to make many things fuse.

 

2- Is it possible to create an electric potential between the center of a sphere and its inside surface? Like having +500 kV at the center and 0 V at the inside surface .

Thanks

 

I think you are describing a very strong polywell type potential well ?

 

2005 WB-6 test results using DD fuel:

 

1) 5.0kV , 800A B-field, 1 neutron count

2) 9.8kV , 750A B-field, 2 neutron counts

3) 12.5kV , 700A B-field, 2 neutron counts

4) 12.5kV , 800A B-field 3 neutron counts

 

SOURCE

 

DISCUSSION

 

 

WB-6 Polywell magnets circa October 2005.

 

 

 

 

 

Single coil Mag field cross section.

 

 

Polywell Magnetic fields. In the center there is a 4 pointed dark spot, that is the potential well, an area dense with electrons.

 

but how would you hold it in place?

 

There is no need to hold a virtual cathode in place. Though Farnsworth's original work on the fusor is much like the picture Jacques posted.

 

http://en.wikipedia.org/wiki/Fusor

 

http://www.damninteresting.com/?p=163

 

 

 

http://www.youtube.com/watch?v=eeMd5LCu7Ag&feature=related

 

 

Recently some have built Farnsworth type Fusors for just a few thousand US dollars

 

 

In a Polywell....The ions form a virtual anode. The electrons form a virtual cathode. This is vacume tube science.

 

From the perspective of being in the center of the Polywell magnets you are looking at the "MGrid" or Whiffle ball:

 

http://www.busybeaks.com/images/wiffle.jpg

 

One would be inside the Whiffle Ball looking out at the faces of the magnetic fields. Lets feed the magnets some current, increasing the potential well strength.

Now lets introduce the electrons, they will collect in the center due to the potential well, as if they are being pushed there by the magnetic fields. They push back at the MGrid.

 

If one introduces a fuel ion inside the cage of the MGrid, the ion sees the electrons gathered at the potential well and races towards it. This is the virtual cathode.

[Jacques]

Roger

I understand Bussard Polywell, but what I am investigating is completly different. The polywell attract the ion to the center to make them collide. For that you create a virtual cathode from electron trapped in a magnetic field. To create the magnetic field I see that the polywell use a huge amount of energy:

4) 12.5kV , 800A B-field 3 neutron counts

That mean a lot of watts!

My design doesn't need any magnetic field just an electric field.

The polywell work with ion colliding in the center and the recirculation of the ion if they don't collide. My guess is that most of the ion won't collide because of the density of the plasma. In my design, the collision of the accelerated ion with the solid boron wall maybe much higher, but I lack the knowledge to compute the collision rate. Anybody out there to help me ? What is the probability that an H+ ion colliding with a solid boron cristal fuse? Some ion will be simply reflacted, other will be deflected and lose their energy and some will fuse...

Also my desing enable the fusion to take place on a big area so the temperature won't be so extreme.

 

I do know that theory says a proton and a B11 need 50 to 65 KeV acceleration to fuse.

And from Colliding Beam Fusion Reactor

The reactivity has a broad peak if the energy of the proton relative to 11B is 580 ± 140 keV.

Who is right? or both are right but I missed something...

[Roger]

Sorry, at 50kv to 65kv of drive voltage. pB-11 fusion happens at 1eV. The probability is very low.

 

The cross section at 60 KeV center of mass (CoM) is 1E-5 barns.

 

Dr. B. detected significant D-D fusion at 20 KeV CoM at which the cross section was 1E-2 barns. pB-11 has a similar cross section at around 130 KeV CoM. Which is a drive voltage of about 50 KV.

 

 

http://fti.neep.wisc.edu/iec/operat1.gif

 

University of Wisconsin chart, but does not show P-B11.