Experimental fusion production and energy efficiency in IEC devices to date has been hindered by confinement limitations. Analysis of the major loss mechanisms suggests that the low pressure beam-beam interaction regime holds the most promise for improved efficiency operation. Numerical simulation of multiple grid schemes shows greatly increased confinement times over contemporary single grid designs by electrostatic focusing of the ion beams. An analytical model of this focusing is presented.Self bunching at a resonant frequency is a klystron type phenomenon.
With the increased confinement, beams self-organize from a uniform condition into bunches that oscillate at the bounce frequency. The bunches from neighboring beams are then observed to synchronize with each other. Analysis of the anisotropic collisional dynamics responsible for the synchronization is presented. The importance of focusing and density on the beam dynamics are examined. Further, this synchronization appears to modify the particle distribution so as to maintain the non-maxwellian, beam-like energy profile within a bunch. The ability of synchronization to modify and counter-act the thermalization process is examined analytically at the 2-body interaction level and as a conglomeration of particles via numerical simulation.
It looks like Dr. Bussard got the re-normalization of energy correct but got the mechanism wrong. It may not be an edge phenomenon at all but a beam phenomenon.
Here is a nice animated picture of an electron simulation showing the bunching. Click on the icon to get it to play.
Here is more from MIT on plasma behavior in an IEC device.
Also, a curious synchronizing collective behavior is observed in simulation. Particles injected uniformly in 3 separate beam paths ‘clump’ and form pulses. As the simulation progresses, these pulses are observed to synchronize between the beam channels. The steady-state behavior under constant injection is then observed to be a global pulse with the majority of the confined ion arrived near the center of the device at the same time.Update: 27 Sept 007 0851z
Here are a couple of good papers on the experiments:
Experimental Procedures - Dietrich [pdf]
Theory Derived From Experiment - McGuire [pdf]