TallDave wrote:The Valencia paper seems to argue the deformation of the magnetic fields in response to the electron pressure produces the effect (by squeezing the cusps closed).
Hi Dave - yes I've read that several times, but as i recall it doesnt dwell on the mechanism, just plows forward with some numbers, showing that if one did exist, it might(should?) be consitent with the desired trapping effect.
that it seems to me was perhaps the easiest bit to show (smaller holes, less leakage isnt that hard a concept to sell).
i was more interested in emergence of the the diamagnetic phenomenon we are supposing to be the WB. afaik, even the mighty Indrek's models 'supposed that', if a WB existed, its effects might be approximated as a 'concentric' mirror polywell - but that is just short circuiting the analysis, to get to some usable simu-data (i think).
though i could be wrong. maybe Indrek's already thought a great deal about the (PIC) internals of WB formation.
quoth Rick:
Here’s what we know and what we don’t know:
1. We don’t have the spatial resolution of the density to see if the cusps are quasi-neutral on the WB-7
why not? if its important, surely we aquire some resolution.
seems to me also that much can be determined from even moderate spatial resolution. - Ive seen LIF and Doppler being used in a couple of papers from IEC 2009. (Nice summary of possible techniques - here
http://www.answers.com/topic/plasma-diagnostic ).
so, i dont see how that is holding us back here.
2. In one-D simulations the plasma edge (which corresponds to the cusp regions) is not quasi-neutral. Therefore, if the cusps are quasi-neutral it must be a multidimensional effect.
but the cusps and the plasma edge are connected, no? they form a discernable common structure. but with further internal discontinuities. so, 'multidimensional' yes, though theres not a great deal here that isnt, surely.
'WB' then, may be the most important metric 'coupling' in the system, so it would certainly be nice to see ut set it down in even a rudimentary dimensional formulation, that could be agreed on.
and some real experimental numbers, obviously
3. Energy confinement on the WB-7 exceeds the classical predictions (wiffleball based on the electron gyro-radius) by a large factor.
...hang on a sec. shouldn't those classical predictions have given you the correct result? theres nothing non-classical going on, surely?
Our conclusion is that both the wiffleball and the cusp recycle are working at a reasonable level.
[/quote]
... there we go again, concluding with tautologies. insert '... that we suppose exist ... '. daemons, top to bottom.
POPS isn't really related, afaict, as WB is a Polywell-specific phenomenon.
i'm not sure i would totally agree with that.
to be sure they are not trying to achieve the same thing in the same way, but i suspect that a) the underlying (Maxwellian) mechanisms ' at play', b) amenable diagnostic methods, have much in common.
why else was Rick top man for the job? and why else did he jump at the chance?
(quite possibly lots of reasons, please dont take the question literally).
whatever gives, we've got a lot of catching up to do with the Tokamak guys when it comes to describing whats going on exactly with 'ones plasma'.