Fig. 4: Scheme of a proof-of-concept cylindrical MHD drive electrolytic cell architecture exploiting the Lorentz force to induce vortical phase separation in microgravity.
From: Magnetically induced convection enhances water electrolysis in microgravity
a, Photograph of a prototype MHD drive with platinum foil ring electrodes and a circular, segmented N52 neodymium arc magnet for efficient oxygen and hydrogen gas collection in microgravity. b, Close-up image of the electrode and magnet arrangement in the device. c, The combination of a radial magnetic field and the electrical current density between anode and cathode generates a Lorentz force on the liquid that induces a vortical flow. Phase separation is initiated due to the centrifugal acceleration and the density difference between liquid and gas phases. r and z denote the radial and vertical coordinates in the axisymmetric plane of the MHD drive, respectively. d, A proof-of-concept test in microgravity generated at the Bremen Drop Tower shows the expected behaviour of the MHD drive: the trajectory of a gas bubble is highlighted, providing a visual demonstration of the vortical flow and centripetal phase-separation effect (Supplementary Video 8). The current density was set to 105 mA cm−2 and 1 M HClO4 (aq.) was used as the electrolyte. Scale bars, 1 cm.
