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Correction to Minimagnetospheres above the lunar surface and the formation of lunar swirls [Phys. Rev. Lett. 109, 081101 (2012)] This Letter was published online on 20 August 2012 with production errors in Table I. The heading in the first column should read as ‘‘Thermal energy, eV.’’ All instances of ‘‘.10’’ should read ‘‘10.’’ The Table has been corrected as of 24 August 2012. The Table is correct in the printed version of the journal.

We describe results from the gun-injected spheromak device SPHEX, which show that the power required to sustain the plasma is initially deposited in a column, about 8 cm in radius, along the geometric axis of the device, and is transmitted from the column to the remainder of the plasma by a radially propagating oscillation at about 20 kHz. These results are relevant to the process of relaxation in spheromak systems

The spheromak device SPHEX has been modified by adding a current-carrying rod along the geometric axis, providing a preexisting toroidal field. We show that plasma can be succesfully injected into such a field from a helicity source; the field assists plasma ejection from the gun and improves the coupling between gun and plasma, so that T e , T i , and the toroidal current all increase with rod current.