x = np.linspace(-15,15,100)
z = np.linspace(-5,5,100)

fig,ax = plt.subplots(1, 1, figsize=(12,4))
pot.plot_contours(grid=(x, 1., z), ax=ax)
ax.set_xlabel("$x$ [{}]".format(pot.units['length'].to_string(format='latex')))
ax.set_ylabel("$z$ [{}]".format(pot.units['length'].to_string(format='latex')))
fig.tight_layout()