Beta

The Beta value of a fusion plasma is given as the ration of the thermal plasma pressure $p$ to the magnetic field pressure $B^2/2\mu \_0$.

$$\text{Beta}=\frac{2p\mu \_0}{B^2}$$

• $\mu \_0$ is the vacuum permeability

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A high beta value is economically desirable. (High magnetic field strength, low and therefore more affordable external magnetic field)