# Questions Regarding Energy Generating Fusion

## Main Question or Discussion Point

Hi All,
I was wondering about some equations/formulae related to Fusion. How much energy/what temperature does it take to initiate Fusion? And how is this amount of energy affected by the different element/isotopes used, pressure, magnetic attraction and other variables?

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Astronuc
Staff Emeritus
Hi All,
I was wondering about some equations/formulae related to Fusion. How much energy/what temperature does it take to initiate Fusion? And how is this amount of energy affected by the different element/isotopes used, pressure, magnetic attraction and other variables?

You're asking for a basic course in fusion. The temperature required for fusion depends on the atomic numbers of the nuclei used in the process, the lowest temperatures being for hydrogen isotopes.

One also needs to understand the concept of microscopic cross-section, which is dependent of the species reacting.

The reaction rate (RR) is proportional to n1n2 or n2/2, where n1 and n2 are the ion densities of reacting species 1 and 2 (e.g., d+t), n where there is one ion species (e.g. d+d).

RR = n1n2<σv>, where <σv> is more or less the integrated probability of reaction. <σv> is a complicated function of temperature and species.

There is no magnetic attraction involved. Magnetic confinement is used to 'confine' the plasma as well as maintaining pressure on the plasma. Magnetic pressure is proportional to the square of the magetic field strength.