An electric discharge in a gaseous environment produces a magnetic field that will make electrons move in cycloid or loop like motions. These looping electrons can then form filaments or coils that stretch out like the old fashioned slinky toy. However, under the right conditions -- such as if the self generated magnetic field is adequate or an external static or rotating magnetic field is applied -- the ends of the spring like filaments can join to form a torus. In this case, the electrons are circling on the surface of the toroid and the protons or positive ions are circulating on the interior like in a race track or accelerator. Kenneth R. Shoulders produced these objects utilizing multiple means, but especially discharges from the tips of sharpened cathodes (or wetted with mercury or tin so they would self regenerate). These vortexes are called EVOs or electron clusters. He learned how to create them, manipulate them, guide them, grow them, launch them, and destroy them at will.
He observed many different track marks from the EVOs he produced. Many of these track marks are very similar or identical to those produced by the Strange Radiation that Alexander Parkhomov has recently reported. Just like with the strange radiation produced by Parkhomov's Ni-H system, plasma electrolysis devices, exploding wire/foil setups, and glow discharge devices, the EVOs produced by Kenneth Shoulders were reported to be capable of inducing transmutations among a wide variety of other effects. All of these systems have a few factors in common: some method of electrical discharge, some source of positive ions, and the presence of a magnetic field (self generated or externally supplied). Even when there is not an obvious source of an electrical discharge, if someone looks deeply they can see possible sources: triboelectric discharge, fracto-emission, and others.
In powder based systems the production of atomic hydrogen seems to be very beneficial, if not a requirement, in producing excess heat and strange radiation. Simply put, exposing nickel powder to ordinary molecular hydrogen at anything less than ultra high temperatures (perhaps near the melting point of nickel where it becomes more permeable) doesn't allow for a sufficient quantity of hydrogen to be absorbed. Instead, one of many methods of accelerating the dissociation of molecular hydrogen into atomic hydrogen should be utilized. One way that seems to work adequately is the utilization of a spillover catalyst in the form of evenly distributed nano-particles or a film: palladium is a commonly used element for this purpose. However, to produce even higher levels of excess heat a spillover catalyst by itself may not be enough.
A plasma produced by microwaves, radio frequencies, direct current, or some other means allows for molecular hydrogen (H2) to be dissociated into atomic hydrogen (H1) before it makes contact with the nickel. This accelerates hydrogen absorption significantly. Moreover, the atomic hydrogen in an excited plasma is likely to have more energy per atom than in an ordinary non-ionized high temperature gas as typically used in many LENR systems. But we can do more! Multiple groups have published papers, patent literature, and experimental data showing that if various quantities of certain elements are added to such a plasma, the energy of the protons increases. Without the addition of argon (which seems to work the best among the noble gases) or small amounts of lithium or strontium that can be vaporized (there are other elements which produce the same effect) the energy of the protons may remain at 5eV or typically slightly less. If these elements are added to the plasma, the energy of the atomic hydrogen atoms can surge up to at least 35eV with some parties claiming even higher energies. Logically, since even after contacting the surface of nickel atomic hydrogen must expend energy to penetrate the surface and move downward into the lattice, having a higher energy should allow for greater penetration. With cycles of hydrogen absorption and degassing, the quantities of hydrogen that can be absorbed and migrate through the lattice can reach very high loading levels. This results in defects and voids in the lattice that can contain highly pressurized hydrogen.
The process of absorbing and releasing such quantities of hydrogen can induce charge separation in cracks and internal cavities. When this happens, electrical discharges can occur in the presence of absorbed atomic hydrogen. This is potentially one source of EVO production. Yet another could be the surface plasmon polaritons that are generated on the surface of the nickel when the electrons of the material are disturbed by charged particle impacts (protons or electrons). These waves amplify wherever there are surface features on the surface like nano-particles, pits, cracks, holes, or spires (Rossi's tubercles?). They can surge upwards or downwards in many cases, and I suggest that if they are stimulated powerfully enough (such by the impact of charged particles produced by the plasma) they could induce "sparking" deeper in the lattice in these micro-cavities. This would result in another source of EVO formation.
There are many ways by which EVOs (described using many different terms) are theorized as inducing nuclear reactions and transmutations. I will not go into these theories in depth for the sake of brevity. However, it seems like the destruction of the electrically charged EVO may release strange radiation. The EVO might be the Active Agent that produces excess heat and transmutations in the lattice while the resulting strange radiation (perhaps sub-units of the EVO with different properties) is capable of traveling through many materials and inducing nuclear reactions, transmutations, and leaving track marks up to meters away. Utilizing an additional layer of LENR fuel around the innermost reactor might stop the strange radiation from being wasted. This is the "mouse" and "cat" configuration. By allowing the strange radiation to produce more nuclear reactions in the reactor instead of allowing it to escape the COP may be increased.
So a recipe for plasma stimulated powder based LENR may not be too complicated. The keys would likely be to produce a plasma with anomalously hot protons that would maximize hydrogen absorption and surface plasmon polariton production to create the conditions for EVO production.
In an almost pure plasma system like the Quark (which closely resembles that of Chernetski's plasma tube, the Correa's Pulsed Abnormal Glow Discharge Device, and a few others) the electrode surface may not need to be hydrogenated because EVO production in the lattice may not be a primary objective. Instead, as described in the literature of Black Light Power, if a percentage of argon or lithium (or what might be more challenging which would be strontinum) is mixed in the plasma, not only are hot hydrogen atoms produced but the plasma can be established at a very low voltage of 2 volts per centimeter or less. This could partially explain the very low voltage required by the Quark after primary ignition of the plasma. A further reduction of the voltage required may be achieved by utilizing optimized geometries of the electrodes. In the image located in the Gullstrom Rossi paper, the electrode looks hollow which could be an example of the use of a hollow cathode to produce an initial pseudo-spark discharge. Other geometries could also be used. Many optimal cathode geometries are reviewed in Kenneth Shoulder's book, "EV - A Tale of Discovery."
Once a plasma is produced, it may be pulsed at a high frequency to achieve the striated or cycloid look described by Me356 and Chernetski as what allows for excess power production. If a very narrow central channel is used, the pulses may be focused even more intently amplifying the effect. For example, instead of Chernetski's design of having a channel the same or greater diameter as the plasma, the channel could be much smaller than the electrode diameter. Moreover, utilizing solenoid coils or permanent magnets (they may be backing the nickel electrodes in Rossi's system) could create a "magnetic mirror effect" or "magnetic trap" that would keep the spiralling EVOs and/or strange radiation concentrated in the middle of the channel. This would prevent the strange radiation from escaping and maximize the nuclear reactions taking place in the plasma. Hence, if a magnetic mirror effect is used, the need for an external "cat" wrapped around the discharge tube would be reduced because the strange radiation would not be wasted. A portion of the excess energy could be in the form of heat and another portion could be in the form of a powerful electro-motive force produced. Chernetski allegedly produced such a powerful electro-motive force that it burnt out a power station. Similar reverse spikes of power were reported by the Correa's.
So the recipe for a nearly pure plasma based Quark system may not be too complicated.
I feel that with existing information various wire/powder plasma assisted LENR systems along with Quark/Correa/Chernetski like systems could be successfully built. Sadly, as always, labor and money are the two most significant barriers.