The left panel illustrates the contour of $\beta_{mag}=\frac{n_eT_e}{B^2/(2\mu_0)}$

The right one shows the contour of $\rho_e/l_d$, where $\rho_e$ is the electron gyro radius and $l_d$ is the plasma debye length. In calculating $\rho_e$, we assume the electron motion is non-relativistic