There is a plate you put between the fire and pot when cooking fresh tomato sauce. What is the plate called?

Question

It is to help make sure the sauce doesn't scorch on the bottom of the pot.

Answer 1

I'm pretty sure it's called a conduction plate.  

Answer 2

they are most commonly called Simmer plates but diffuser plate is used also

Answer 3

I've always referred to this as a heat diffuser plate.  We used one on our boat for just such cooking.