Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

my question is simple. How can we calculate the temperature needed in order to do the nuclear fusion things , and also the temperature after the reaction successful.

enter image description here

If you can describe it, it would be really cool. I just want to know about it


share|cite|improve this question

marked as duplicate by John Rennie, Kyle Kanos, Brandon Enright, Qmechanic Apr 7 '14 at 13:44

This question was marked as an exact duplicate of an existing question.

possible duplicate of What is the lowest possible theoretical temperature that nuclear fusion can occur at? – user42733 Apr 6 '14 at 12:46
up vote 0 down vote accepted

Firstly, fusion doesn't happen in the way depicted in the question. Four protons don't participate in a 4-body reaction. Instead there are many intermediate steps:

enter image description here

Each step has its own reaction rate. The overall reaction rate is determined by the rate limiting step. The proton-proton reaction is the rate limiting step in this case.

It is important to think in terms of the rate at which a reaction occurs, rather than whether or not it will occur.

The reaction rate will depend on temperature and pressure. In the Sun, pressure is ~265 billon bar, so the reaction can proceed at 10-15 million K. The rate of reaction is actually very low, the center of the Sun only produces energy at rate of ~277 Watts per cubic meter. On Earth, we can not built a reactor with pressure this high, so higher temperature is needed. Different reactions such as starting with deuterium or tritium are used to avoid the need for the proton-proton reaction. Then fusion could be achieved in the ~100 million K range for example.

share|cite|improve this answer

Not the answer you're looking for? Browse other questions tagged or ask your own question.