Parametric decay of a magnetic island structure

It is shown that a spatially periodic magnetic island structure can decay into a tearing mode and long-wavelength magnetohydrodynamic fluctuations. The tearing mode has a linger wavelength than that of the island structure, and the growth rate is proportional to $\text{?}{}^{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}$, where ε is the ratio of the reconnection magnetic flux to the shear field flux in the original structure.