Heli-Arc or Gas Tungsten Arc Welding (GTAW), also Tungsten Insert Gas (TIG) are basically all the same process of using a constant current plasma arc to bond non-ferrous metals together. Like other welding processes, there can several different adjuncts to the same basic process depending on the base metals and the type of service required for the bonded joint.
TIG welding of copper and some of its alloys is possible, but in order to get a seam free of oxidation and porosities, shielding gas needs to be provided on the root side of the weld. Alternatively, a special "backing tape", consisting of a fiberglass weave on heat-resistant aluminum tape can be used, to prevent air reaching the molten metal.
This process is much slower and more expensive due to the possible occurrence of hydrogen porosity of the joint causing the joint to become brittle, losing its malleability. Automated welding can produce quality welds in this process, however the equipment can run into the hundreds of thousands of dollars.
I'd opened a blog under a title like GROUNDING UNDERWAY, or some title I can't remember, but I'm coming over here because this thread is right to the point.
Like another member, I also will print this out for future reference, as this is the most intensive discussion of the metallurgical and chemical aspects of grounding I've ever run across.
My one-wire experimental ground is now all the way to the uphill limit of the lot, right at the mulch pile, and it already demonstrates two things:
The single ground wire is carrying a readable signal uphill, where before i only had noise, but the main signal strength is still near the vertical antenna many feet downhill.
The next stage of experiment is to add additional ground wires (radials) spreading off in different directions as has been suggested, to further improve the signal coverage.
Interestingly, the 1550kHz signal is being improved near to the transmitter but the far field is still the same as it was before.