Vertical force balance and energy density in the vicinity of the loop of Chen et al. (2014, 2015). Panel a: vertical force balance in terms of acceleration with contribution from the pressure gradient ∇p (orange solid line) and the Lorentz force J × B (black) divided in the magnetic pressure gradient ∇B²/ 2μ₀ (red) and the magnetic tension force (B·∇)B/μ₀ (blue) plotted over height in the vicinity of the loop (x = 75 Mm, y = 30 Mm). We also show the plasma β for the same region (black dashed) (y-axis on right-hand side). Panel b: energy densities of the total magnetic field B²/ 2μ₀ (black line), potential magnetic field and the induced magnetic field shown together with the thermal pressure p (orange). The horizontal black dotted line in the upper plot represents the zero value. We refer to Sect. 3.4.