Talk-Polywell.org

The question is: How wide will your beam be? [and if greater than 5 barns in cross-section, then how will you ensure nucleii in the edge react with the others?]

Diameter of the beam will be highly dependent on electron current.
And how fusion goes on the Sun having a diameter equal to 1,392,000 km and cross section of various reactions in which as a rule are less than 5 barns?
How you can kill somebody at a long distance with machine gun when somebody has sizes 1.8x.0.6 m and bullet's dispersion is about 10m? You simply shoot a lot of bullets.

So what electron current are you expecting to need?

For plant's net power of 1,000 MW we need two ions beams with currents 250 A each and electrons current of about 60 A.
This is in case of deuterium + tritium reactor when only 4 MeV of energy per one fusion event yields the net production. The rest 13.6 MeV - energy expenses.
These are very high currents for charged particles beams.
But it is not impossible. The main restriction is not in current but in a current density.
For example for TOKAMAKs now using multi-aperture concept are made deutron accelerators with particle's energy 1-2 MeV and current 3 A.
10 years ago for the same purpose was a talk 200-300 keV and 25 A.

Well, at least you've confirmed that you are not being serious about this. For ions at a few 10's of keV, you need of the order of megaAmps to keep them confined, and that is whilst permitting beam width to be several 10's of cm. If you want narrower beams, you need higher currents still.

250A! What mag field do you seriously think you'll get from that!?

In heavy ion fusion tens thousand amperes are used. In impuls.
In Tokamaks for neutrals injecting a few constant current variable voltage accelerators with total current of tens amperes.
I am repeating one more time: the main restriction with high currents accelerators is not in current's level but in its density.

I missed what did you claim. If you about pinch of combined current you are wrong.
Charged particles beams dramatically compressed passing through even the cloud of opposite charged particles.

And we will have a combination of three factors:
Compensation of space charge + magnetic attraction + low temperature.
And compressed beam will be narrower at least on order.
And if you claim "several 10's of cm" -on two orders.
The key word here is low temperature - at least 500 times lower than in other fusion methods.
Have you ever heard about electron cooling first offered by G.I. Budker? Relativistic electrons will radiate and the temperature will not exceed a few eV-s.

Does low temperature imply proportionally low pressure of gas at the same density?
And consequently possibility of stronger compression?

So, a very effective focusing and consequently a strong self-magnetic field confining the particles. Unattainable e.g. in TOKAMKs with even mega-amperes axial (toroidal) currents.

And total current not 250 A but 560 A for large commercial scale reactor. It will be enough for focusing to up to 0.5-1 cm diameter.

Regarding initial ion source
Here is a link of Japanese constant current ions gun giving the current 3 A of particles' energy 500keV with aperture 20'000 cm2 = 2 m2.
http://www.jaea.go.jp/english/news/p100 ... ndex.shtml
So, for ion gun might to give us 250 A we need about 80 times bigger aperture = ~160 m2.
This corresponds to the diameter of about ~14.4 m in case of a single round shaped ion source (let’s call this diameter as “equivalent aperture”)
Nobody built such big ion source yet. But technically it is quite possible.