Yes, it looks like the machine is AC.
Note: aluminum is difficult to weld and is a good job for professionals.
A few years ago, out of curiosity, I tried a set of aluminum bars "welding" electrodes. The result was cruel... I'm a welder.
The smoke smells like it will melt my nose in a short time. So no, you should save your money.
I don't recommend using an electrode larger than 3/32 of an inch, because it claims to run only 100 amperes, and in the real world, it's unlikely to give you too much time.
I suggest using your machine welding electrodes:
E6011
E6013
E7018 AC -
Note that these are all electrodes designed for AC. Other types of electrodes can be used, but not well run, and not easy to start.
