The Naval Air Warfare Center, Weapons Division, China Lake, CA intends to procure on an other than full and open competition basis the following:1) Polywell Fusion Device-Ion Injection Gun Research (Quantity - 1 each). This requirement is sole sourced...
While this is up as a topic, can someone remind me what the ion gun has to do for its spec.? I mean, what exit potential does it operate at, what is the transit velocity requirement and its trajectory accuracy, &c.?
If the exit potential is the magrid potential, then won't it go straight through the device and out the other side (with the same transit velocity)?
If the exit potential is slightly more negative than the magrid potential then the ion could be tuned to slow down as it approaches the magrid so that it gets to the edge of the wiffleball with zero velocity. But if the ion is slowed down to zero velocity and there are also 'cold' electrons hanging around at the cusp (through which it is shot) then why wouldn't the ion just re-combine with the nearest electron? A 'zero' energy ion plus a 'zero' energy electron is [called] 'an atom'!
When I looked at the problem I decided what was needed was not high ion energy, but carefully controlled ion injection at low energy. I also would have wanted very complete ionization, but again without injecting too much energy.
One thought I had was to generate the ions and then use a grid to slow them back down again.
Its an interesting problem with a lot of tradeoffs.
Oct 2008?. I think it must have been one of the "keep alive" contracts. Might it have been used in WB7.1 around Jan 2009?
Concerning aiming and energy. I've wondered if feeding the ions into the cusp with just enougn energy to overcome the magrid potential will leave low energy ions traped on field lines that pass close to the WB border. Would the potential well then pull the ions into the WB?. Since the ions would not be pulled exactly towards the center, on subsequent return the ion potential well peak would not be quite as high (stay out of the magnetic domain) because of the less than perfect efficiency of the potential well (focus). Is there any energy loss in pulling a charged partical off a magnetic field line?
As far as injecting ions towards the center, the cloud of electrons (them-selfs injected from at least several guns to cause dispersion as they met in the center) should defocus them enough that the opposite cusp is 'missed'. Subsequent passes would further disperse them- leading towards thermalization and decreased confluence. If needed to quickly disperse them from a perfect focus towards the opposite cusp, two or more ion guns might be used. This would also make it easier to reach the nessisary ion current.