"The charge of a beam weapon is not just a beam of atoms, but it's also a unique "liquid plasma", a substance that allows you to inflict maximum damage to the target. It can also be used to make a working discharge cell. Nonsense, of course, but that's how it works. Probably."
Can be located in the lava area next to the Knight-errant. Warning! You will need an engineering suit in order to survive the immense heat of that area, so make sure you research and craft it first. Can also be found in Smuggler's caches.
Use the Grabber to collect.