To begin, this thread isn't to debate the existence of the Rossi Effect or high powered nickel-hydrogen "cold fusion" or LENR. If you want to insert the same naysaying, overly skeptical remarks that you post repeatedly on other threads, please stay away from this thread. If you post on this thread please realize everything here is based on the assertion that the Rossi Effect is real and works. Debate on that issue is-not-allowed.
I'll start with a few fundamental "first principles" about Ni-H fusion or the "Rossi Effect" that I hope most of us can agree are probably accurate.
1) For the process to begin, hydrogen must be adsorbed to the surface of clean, oxide free nickel.
2) In areas where there is a greater quantity of adsorbed hydrogen, such as in grain fractures, cracks, pores, and cavities, there can be a greater quantity of absorbed hydrogen.
3) A greater quantity of absorbed hydrogen that has made it into the lattice (or defects/cavities inside the lattice) makes it more likely for reactions to occur than if a lower level is absorbed.
Now, it is not easy for the average replicator -- or even an advanced replicator without a sophisticated lab -- to measure the content of hydrogen actually absorbed into nickel. However, like someone has said before, nickel usually absorbs a relatively low quantity compared to other metals such as palladium or titanium.
We know that the successful replicators, such as Parkhomov, Songsheng, Stepanov, Me356, and others, have been able to induce high powered Ni-H (usually plus lithium) fusion without super exotic methods to enhance hydrogen absorption. Some groups of used nickel with a high surface area to increase hydrogen absorption and others have used a combination of LiAlH4 AND hydrogen from an external source. But ordinary nickel wire or non-mond process nickel seems to work too. A massive surface area doesn't seem to be required.
This makes me think that a huge level of hydrogen absorption is not required. This could mean...
1) The whole nickel particle or wire doesn't have to absorb so much hydrogen the entire sample of nickel is converted to nickel hydride.
2) Probably a high-ish level of hydrogen only exists near the surface of the wire/powder.
3) The high failure rate of NiH experiments probably means that achieving enough hydrogen absorption is difficult regardless if you use bulk nickel or powder.
Now, if we want to maximize absorption of hydrogen by nickel, the most common sense methods have already been discussed: cleaning the nickel of oxides (with acid, ultrasound, hydrogen reduction) and vacuuming the nickel to remove oxygen and other gases trapped inside. Once this is performed, the actual hydrogenation can potentially be enhanced by another of methods. For example, the use of reverse spillover catalysts (copper and palladium), electropositive hydrogenation supporters (lithium, potassium), the application of voltage to the fuel (somehow this can enhance absorption in different ways depending on which polarity is applied to the nickel), the insertion of atomic hydrogen in the vicinity of the nickel (hot tungsten filament/tube, glow discharge, etc).
I don't have proof, but I seriously think that the number one reason why replications fail is a lack of hydrogen absorption. This issue could be more complex than we realize. For example, we may (or may not) need layers of nickel that have been loaded up to the beta-phase rather than the alpha-phase. We might not need the whole nickel powder particle or wire to be loaded to this level, but we may need above a certain critical amount at least in certain spots.
To figure out to what degree hydrogen needs to be loaded, there will need to be exhaustive testing. This level of testing may or may not ever be performed by an "open" replicator. In the mean time, when less exhaustive replication attempts are made, I suggest that every effort is made to maximize hydrogen loading to a reasonable extent. In Songsheng's tests, a maximum of 5-6 bars of hydrogen pressure was achieved if I'm reading his charts correctly. Interestingly, after adsorption or absorption occurred, he added more hydrogen. My thinking is that a pressure of beyond ten bar may not be required if proper cleaning and vacuuming is performed. Focardi produced excess heat on a number of occasions utilizing one bar or less.
If we can achieve an adequate level of hydrogenation, my guess is that stimulation -- at least in theory -- will be simple. Of course systems will need to be robust enough so that components and resistors don't fail from VERY RAPID heating surges to thermal shock the nickel.
The level of understanding of what's probably involved with the Rossi Effect is greater than ever. Now we just have to put it to use!
(Any practical guidelines or suggestions from Me356 would be appreciated!)