Which is pretty bad IMO.
Should be able to stack up 3-5 charges at least.
He's already confirmed that it isn't an instakill beam. (J.E)
Yeah it's good that it isn't an instant win but seeing as it's not that powerful I don't see why it couldn't stack it's charges up to a certain limit.
So that say I have 3 charges stacked up, then I can still only use them 5 minutes apart, so that I can't spam those three instantly.
That way, it's not too powerful and more useful. (imo)
Except the energy unleashed in such a bombardment is vast, so I doubt even in the 50s future, that any ship they had could carry an orbital cannon with enough capacitors to hold more then a single charge.
And before you say they could have added more, again remember this is the 50s future, and the first manned space trip wasnt till 61, the first spacewalk was in 65, And the first time someone had to spacewalk to assemble something wasn't till the early 80s. That being said, they would have had to pack the ready to use orbital cannon into a rocket, again, limiting the capacitors for holding a charge.