I realize I'm missing something here about electron movement. What force keeps the electrons moving from the emitters to the center of the chamber? It would seem that since the outside grid is + at a potential of ~100KV, the easiest path would be from the emitter to the nearest point on the + grid.
Also, is the well at ground potential?
Dumb question - electrons...
Inertia also helps as well.
When the electrons are moving past the grid they are at high velocity and thus are only slightly deflected even if they are off center.
Dr. B. said angular alignment was important. Something that will have to be explored in the prototypes.
When the electrons are moving past the grid they are at high velocity and thus are only slightly deflected even if they are off center.
Dr. B. said angular alignment was important. Something that will have to be explored in the prototypes.
Engineering is the art of making what you want from what you can get at a profit.
The well works better if it is slightly negative. With an outer positive MaGrid you need a negative core to ensure the ions try to accelerate into the center.
This is possible because the ions act similar to a physical wall. If you have a plasma near an isolating wall, the electrons hit the wall more often because they are lighter. That builds up a negative potential which attracts the ions, and eventually you get a balanced flow.
The polywell needs to start up some how though. Bussard talks about the start up problems in some of his papers, so there is a specific process he had in mind. If nothing else, you could turn on an electron source on one side of the device with the MaGrid positive, and the electrons would coast through the center and back out the other side. If there is gas in it, some ionization takes place and you can essentially light the spark.
It is important to remember the whole thing is dynamic. Electrons don't stay in the center, they bounce around. The trick is to maintain an average of slightly more electrons in the center all the time (or at least during some given pulse time). Any one given electron won't be there long, but lots of them will.
This is possible because the ions act similar to a physical wall. If you have a plasma near an isolating wall, the electrons hit the wall more often because they are lighter. That builds up a negative potential which attracts the ions, and eventually you get a balanced flow.
The polywell needs to start up some how though. Bussard talks about the start up problems in some of his papers, so there is a specific process he had in mind. If nothing else, you could turn on an electron source on one side of the device with the MaGrid positive, and the electrons would coast through the center and back out the other side. If there is gas in it, some ionization takes place and you can essentially light the spark.
It is important to remember the whole thing is dynamic. Electrons don't stay in the center, they bounce around. The trick is to maintain an average of slightly more electrons in the center all the time (or at least during some given pulse time). Any one given electron won't be there long, but lots of them will.
Electrons push back?
Hi, polywell newbie here, I have another basic question (that I suppose could be answered if I had a physics 101 book):
When enough electrons are in the center of the polywell, the electrons "push back" on the magnetic fields produced by the circular magnets, changing the magnetic field lines and "squeezing the cusps nearly closed" (I'm paraphrasing from other reading material I've found...I don't want to give the impression that I know what I'm talking about
).
My question is what property of electrons "pushes back" on the magnetic field lines of the polywell magnets?
When enough electrons are in the center of the polywell, the electrons "push back" on the magnetic fields produced by the circular magnets, changing the magnetic field lines and "squeezing the cusps nearly closed" (I'm paraphrasing from other reading material I've found...I don't want to give the impression that I know what I'm talking about
).My question is what property of electrons "pushes back" on the magnetic field lines of the polywell magnets?
It is my understanding that it has to do with the electron as a subatomic particle spinning around and moving at a certain vector. When the electron encounters the magnetic field line it transfers some kinetic energy as it "hits" the magnetic field line. This interaction alters the spin of the electron and direction of travel as the electron "slides" along the path of least magnetic force. I liken it to punching a curved lubricated wall and having your fist slide along the curve of said lubricated wall. Electrons do have mass albeit very very small amounts, and they are in motion. Of course, keep in mind that though electrons are thought of as "energy" all matter is basically energy tied together in various ways(don't ask me how exactly) that end up determining their properties as matter(elements) or subatomic particles. The bigger fish on this site may have a better explanation and correct me if something I said was in error. I could be incorrect and I could also have failed to fully understand what you are asking.
I hope I helped.
I hope I helped.
Re: Electrons push back?
Electrostatic attraction. They want to get away from their negatively charged brethren and kiss the positively charged Magrid.zretawt wrote: My question is what property of electrons "pushes back" on the magnetic field lines of the polywell magnets?
Hmm, ok thanks, I think I understand. The electrostatic force causes a change in the magnetic (force) field. In the IEC for dummies video the field lines must be representing the combined magnetic and electrostatic forces.
The specific phenomena I was curious about is depicted here:
http://youtube.com/watch?v=jmp1cg3-WDY&feature=related
in a before-and-after shot at 1:22 then at 1:24.
The specific phenomena I was curious about is depicted here:
http://youtube.com/watch?v=jmp1cg3-WDY&feature=related
in a before-and-after shot at 1:22 then at 1:24.
The math here might be daunting, but there are a lot of references. And the pictures explain what you are basicly asking about.
It's messy and complicated - that's what makes it so much fun to try to figure out.
It's messy and complicated - that's what makes it so much fun to try to figure out.
p-B11 p-p or B11-B11 collisions
Thanks very much for the previous answers. Another "dumb question":
What is expected to happen in a p-B11 polywell fusion reactor when p-p or B11-B11 collisions occur? Has this been covered elsewhere in this forum? Thanks.
What is expected to happen in a p-B11 polywell fusion reactor when p-p or B11-B11 collisions occur? Has this been covered elsewhere in this forum? Thanks.
I'm not sure it has been covered, but you can find some data in the National Nuclear Data Center. It takes some digging around because there is so much information, but the main key word you want to work with is "cross section". There are scattering cross sections and nuclear reaction cross sections. Elastic scattering can be computed fairly well using classical electrodynamics, but for nuclear reactions you need to get into quantum mechanics. It's easier to measure it.
I think the average energy will be too low for nuclear reactions for B-B, but I'd have to dig thru the tables to see how p-p goes.
I think the average energy will be too low for nuclear reactions for B-B, but I'd have to dig thru the tables to see how p-p goes.
When a stray electron travels along a magnetic field line (e.g. along B1) back into the polywell, an adjacent magnetic field (e.g. B2) prevents another revolution on B1 because the magnetic force counteracts the force from B1, setting the electron adrift into the well. Is this correct? Has it been shown that electron recirculation for maintaining the well is a "stable" process?
Again, please forgive my naivete. Thanks again for your insight.
Again, please forgive my naivete. Thanks again for your insight.