What factors are needed to make fusion work?

Question

Please no long detailed answers.

Answer 1

Fusion requires a lot of initial energy to overcome Coulomb forces on the atomic scale. This energy is found via heat and pressure.

Unfortunately the heat required to reach this energy level are beyond anything we have achieved.

Cold fusion is achieving this goal without the great heat.

Answer 2

We look at three things
density
temperature
time

The hotter, denser, and longer we can confine a plasma the high the fusion output.

Answer 3

Extremely high temperatures and pressures!!!