Some evaporation sources need lots of current, but have modest voltage requirements, for example needing 400 amps, but dropping less than a volt.
I imagine one good way to get a high ac current would be to pass a big fat wire through the center hole of a toroidal 50 / 60Hz power transformer.
For example, AnTek makes nice low-cost toroidal transformers,
These transformers have plenty of room inside their center hole (1.5") to pass even several turns of big wire, etc.
I purchased a 1kVA part, p/n AN-10265, for $100. Using a one-turn secondary to measure the turns ratio, I found 225 primary turns. This means we'll get up to 530mV with a one secondary turn, 1.06V with two turns, or 1.6V with three turns, and we can draw up to 1875, 938 or 625A respectively.
The question then becomes, what's the best way to control the total output current, to obtain a precise oven temperature.