Increasing the magnetic helicity content of a plasma by pulsing a magnetized source

By operating a magnetized coaxial gun in a pulsed mode it is possible to produce large voltage pulses of duration $\ensuremath{\sim}500\text{ }\ensuremath{\mu}\mathrm{s}$ while reaching a few kV, giving a discrete input of helicity into a spheromak. In the sustained spheromak physics experiment (SSPX), it is observed that pulsing serves to nearly double the stored magnetic energy and double the temperature. We discuss these results by comparison with 3D MHD simulations of the same phenomenon.