Re: Is pulse operation a design "feature" of Tokamaks or just what you can do so far?
No it's a core feature. It's like a big transformer it can only work while the field is changing.
To make it worse the more power you need to contain the faster you need to raise the field so you can make it cycle on-off over hours at low power but minutes at GW powers.
Even worse-worse, like a transformer you go through zero field switching between +/- and at that point there is no field to hold the plasma which then hits the walls and melts your machine. So you need to dump the plasma and start again every half cycle.
The big advantage of the stellarator is that the plasma generates it's own permanent containment field, the drawback is that you have an amazingly complex job to control it.