A circuit in my project uses rapidly switching MOSFETs to control current flow, and as a side effect, the current demand on the DC source varies rapidly.
The FET is switching at somewhere between 10kHz and 100kHz, and the current demand switches from 100A to about 150A every period at about that frequency. For example, this is a slightly less extreme example from LTSpice (ignore the small inductive spikes):
The DC source is a large 200V/1000A generator/rectifier from the 1950s, and likely can't handle any changes above ~60Hz. Is there a device or component I could add that could draw an essentially constant amount of current from the rectifier, but handle the rapid changes in load to maintain a constant voltage? A (very) large capacitor across the device could do it, but I'd prefer something a little more elegant and less likely to kill me (or at least advice on how to use something like that safely).