Apart from restricting the mass that is placed into the reactor, how else can the speed of nucleur fusion be controlled

Question: Apart from restricting the mass that is placed into the reactor, how else can the speed of nucleur fusion be controlled to ensure the safety of the research?
- Keywords:
  fusion,
  mass,
  nucleur,
  reactor,
  safety,
  speed
Asked by 05braceye to David on 19 Jun 2011.
- David Armstrong answered on 19 Jun 2011:
  
  The great thing about nuclear fusion is that it is easy to stop. Fusion can only occur at high temperature in a plasma. There is actually never very much material in the reaction at anyone time(just a few grams). To stop the reaction all that needs to happen is let the plasma cool down a little. The plasma is controlled by a magnetic field, by changing this the plasma can be cooled and the reaction stopped. This means fusion is safe as there is no way for problems like meltdown to occur.

Question: Apart from restricting the mass that is placed into the reactor, how else can the speed of nucleur fusion be controlled to ensure the safety of the research?