Interplanetary hydromagnetic clouds as flare-generated spheromaks

Solar flare-generated interplanetary clouds are proposed to be treated as oblate spheromaks (oblamaks) with predominantly force-free magnetic field. The solution found for a force-free field equation in spheroidal coordinates makes it possible to describe the spheromak magnetic fields by a series of spheroidal wave functions. Comparison between theoretical and experimental results is shown in the case of the hydromagnetic cloud from the November 22, 1977 flare (STIP Interval IV).