Search found 794 matches

by Art Carlson
Thu Jul 17, 2008 9:09 am
Forum: Theory
Topic: All that can go wrong with recirculation
Replies: 112
Views: 33508

Along the same lines, for the line cusps I expect an electric field in the plane of the electron fan. That should push them aside so that they possibly will miss the sweet spot coming back in. Even if the net push per excursion is less than a gyroradius, this effect may limit the effective recyclin...
by Art Carlson
Thu Jul 17, 2008 8:38 am
Forum: Theory
Topic: All that can go wrong with recirculation
Replies: 112
Views: 33508

Why? Maybe if you are talking about the volume-average density, but why should the peak density be much less than the density inside? Sure, but I think the overall relative densities are going to be more important to the force on the ions. My comment was referring to the electric field perpendicula...
by Art Carlson
Thu Jul 17, 2008 8:25 am
Forum: Theory
Topic: All that can go wrong with recirculation
Replies: 112
Views: 33508

Hmmm? I guess I'm not sure why that matters, if there are far more electrons on the inside and the Magrid between the ions and the outside. Are you saying you think they're energetic enough that they can climb all the way out, despite the gradient? I don't understand your comment. Not even grammati...
by Art Carlson
Thu Jul 17, 2008 8:17 am
Forum: Theory
Topic: All that can go wrong with recirculation
Replies: 112
Views: 33508

I would expect the star-shaped potential well to be quite blunted and nearly spherical by the time you get down to the ion formation altitude. This minimizes ion loss pretty much as well as a spherical well. Why would you expect that? The Debye length is very small, so you have to have ions everywh...
by Art Carlson
Wed Jul 16, 2008 4:15 pm
Forum: Theory
Topic: All that can go wrong with recirculation
Replies: 112
Views: 33508

In a geometry with a scale length R, the potential of the sheet is on the order of (kT/e)*(R/lambda_D), which is huge compared to the voltages in the system. But it's still small compared to the potential of the interior, and the Magrid is out there too. ??? I am working on the assumption that temp...
by Art Carlson
Wed Jul 16, 2008 3:31 pm
Forum: Theory
Topic: All that can go wrong with recirculation
Replies: 112
Views: 33508

What I picture is a sheet of electrons, with a thickness of a few electron gyroradii and a density a few times less than the density in the high beta region. Should be 1,000 - 10,0000 times less dense, overall, outside vs. in. Why? Maybe if you are talking about the volume-average density, but why ...
by Art Carlson
Wed Jul 16, 2008 2:12 pm
Forum: Theory
Topic: All that can go wrong with recirculation
Replies: 112
Views: 33508

Let me make another try to get a grip. We want to try to confine ions electrostatically. We try it with grids but find that the losses due to ions hitting the wires are too big. We try it with a bunch of electrons confined by magnetic fields. If we consider perfectly confined electrons, we find that...
by Art Carlson
Wed Jul 16, 2008 1:00 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

4. The idea behind inertial electrostatic confinement is that you inject electrons with directed (radial) energy into the system. These electrons then form a virtual cathode by giving up their kinectic energy to potential energy in the virtual cathode (hence the importance of inertia). You don’t wa...
by Art Carlson
Wed Jul 16, 2008 12:40 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

Art: 2. The general rule of thumb on ion collisions is that ion collisions in the core add angular momentum to the ions (thermalization) while collisions in the edge remove angular momentum. The reasons edge collisions remove angular momentum is that as the ions reach their radial turning point, th...
by Art Carlson
Wed Jul 16, 2008 6:48 am
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

A few posts up, you say "deuterium always comes with a small fraction of tritium." Really? How small? We believe all the deuterium ever created was produced in the "big bang", and is 13 billion years old. It can't survive in stars, and even brown dwarfs can burn it. But tritium? About a 12.5 year h...
by Art Carlson
Wed Jul 16, 2008 6:34 am
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

I can't resist. At the risk of exposing my ignorance I believe your number of 10^30 neutrons per second for a useful reacter is off by at least a facter of a billion. I didn't mean per second but in its lifetime. 30 years = a billion seconds, so the math works out. How relevant this comparison is, ...
by Art Carlson
Tue Jul 15, 2008 8:20 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

Let me see if I can summarize this. The basic claim is that the electric potentials will take on the shape of the magnetic field structure. This will give electrostatic potentials that are defocusing for the ions and they add angular momentum to the ions with each pass (i.e. we have an ion optics p...
by Art Carlson
Tue Jul 15, 2008 7:38 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

I hear you ... all we've seen from the earlier work is a wiff of fusion. I'm content, at the moment, to await peer-reviewed results to see if the scent is now stronger, and if the dogs know which way to track. Be my guest. I got a bit riled, but I didn't need to. The money is spent and the data are...
by Art Carlson
Tue Jul 15, 2008 4:29 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

You guys are amazing. The theory of this machine is really weak, but the experimental data is non-existent. The only positive data you have is a number of neutrons that I can count on my fingers. A reactor will have to produce around 10^30 neutrons. ZETA produced millions of neutrons per pulse in t...
by Art Carlson
Tue Jul 15, 2008 3:35 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 32166

You guys are amazing. The theory of this machine is really weak, but the experimental data is non-existent. The only positive data you have is a number of neutrons that I can count on my fingers. A reactor will have to produce around 10^30 neutrons. ZETA produced millions of neutrons per pulse in th...