I just found this paper published in no less than the Physical Review Letters:
"Experimental Observation of a Periodically Oscillating Plasma Sphere (POPS) in a Gridded Inertial Electrostatic Confinement Device" by Park, Nebel, Stange and Murali, 2005.
As you might imagine getting a paper on IEC into PRL is, well, not easy. D.C. Barnes had one in '93 and before that you'd have to go back to the 60's I believe.
Park,Nebel,Strange,Murali is recognition and follow up of work done by Barnes and Nebel (Los Alamos) in '98:
"Stable, thermal equilibrium, large-amplitude, spherical plasma oscillations in electrostatic confinement devices" Physics of Plasmas, Barnes and Nebel, 98
AFAICT the POPS reasoning goes as follows:
It was recognized that collisions pointed out by Nevins/Rider for fusors/Polywell IEC fusion made net power unlikely.
"The high energy cost of maintaining a beamlike ion energy distribution makes it difficult to produce net fusion power and is considered to be a crucial obstacle facing IEC based energy devices..." - which we well know ad nauseum on this forum. So B & N came up w/ an oscillating scheme where _all_ of the ions are phased locked and move towards the focus together. Moreover they did the analytical work to prove on paper that this could be done. This PRL paper is observation of the thing, living, in the UW lab. They use a virtual cathode ala Tuck et al or Bussard:
"...A new electrostatic plasma equilibrium that should mitigate this problem has been proposed by Barnes and Nebel [12,13]. This concept uses electron injection into a spherical device to produce a virtual cathode with a harmonic oscillator potential (constant electron density). An ion cloud immersed in the virtual cathode [referred to as the periodically oscillating plasma sphere (POPS)] will then undergo a harmonic oscillation where the oscillation frequency is independent of the amplitude. By tuning the external radio-frequency (rf) electric ﬁelds to this naturally occurring mode, it is then possible to phase lock the ion motions. This simultaneously produces very high densities and temperatures during the collapse phase of the oscillation, when all ions converge to the center with their maximum kinetic energies. It has been shown that an analytic solution for the POPS oscillation exists and has the remarkable property that it maintains the ions in local thermodynamic equilibrium at all times . In particular, the equilibrium state survives even though the plasma density and the temperature may vary by several orders of magnitude during the POPS oscillation..."
Barnes&Nebel noted in a related paper that there was a space charge problem that had to be solved for a working POPS. Then in April of this year this came out:
"Space Charge neutralization in IEC plasmas", Evstatiev, Nebel, Chacon, Park, Lapenta in Physics of Plasmas.
Discuss. Also, how well could this thing be applied to Polywell?