So is this possible to connect a power bank to an ac outlet (I know that there are AC capacitors) and have them charged for the transformer driven pulse welder to use when needed very high currents

I'm surprised no one caught this. Capacitors PASS AC. Capacitors STORE DC.

 

During CD welding the required welding energy is taken from previously charged capacitors. This energy is transferred via a thyristor and a welding transformer.

While that may be true in a commercial CD welder, I don't think it is in a consumer or DIY CD welder. Don't most DIY CD welders use the transformer before the rectifier? Dumping the stored DC directly into the weld?

 

Wait, can't I just take a solar power inverter from 12v to 220v that is capable for about 7-10kw and connect the inverter to a car battery?

Like this one:
https://www.ebay.com/itm/3000W-1000...00w&LH_BIN=1&_from=R40&rt=nc&LH_TitleDesc=0|0