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A novel plasma state has been found [C.~Ak\c{c}ay, J.~Finn, R.~Nebel andD.~Barnes, Phys.~Plasmas \textbf{24}, 052503 (2017)] in the presence of auniform applied axial magnetic field in periodic cylindrical geometry. Thisstate is driven by external electrostatic fields provided by helicalelectrodes, and depends on radius $r<r_w$ and $m\theta-n\zeta$, where $m=n=1$,$\theta$ is the poloidal angle, and $\zeta=z/R$ is the toroidal angle. In thisreference, the strongly driven form of the state was found to have a strongaxial mean current density, with a mean-field line safety factor $q_0(r)$ justabove the pitch of the electrodes $m/n=1$ in the interior, where the plasma isnearly force-free. However, at the edge the current density has a componentperpendicular to $\mathbf{B}$. This perpendicular current density drives nearlyAlfv\'enic helical plasma flows, an notable feature of these states. This stateis being studied for its possible application to DC electrical transformers andpossibly tailoring the current profile in tokamaks. We present results onseveral issues of importance for these applications: the transient leading tothe steady state; the twist and writhe of the field lines and their relationwith the current density; the properties of the current density streamlines andlength of the current density lines connected to the electrodes; thesensitivity to changes in the velocity boundary conditions; the effect ofvarying the radial resistivity profile; and the effects of a concentratedelectrode potential.

Properties of the electrostatically driven helical plasma state