The big untouched mystery is how these things collimate the beam so exactly.
In order for all the mass to end up going in exactly one direction, so focused, something would have to get them started off that way. Any sort of thermal phenomenon would need a parabolic reflector/nozzle.
Currently favored is some sort of electromagnetic process that works like a particle accelerator, applying a linear electric field to highly-ionized nuclei over thousands or millions of km.
The "geysers" coming out of Enceladus would likewise need parabolic nozzles to stay collimated, so must be similarly electromagnetic. Unfortunately the notion was first promoted by reviled "electric universe" enthusiasts, so astrophysicists need to file the serial numbers off before they can acknowledge it.