The ascent of single argon bubbles with equivalent diameters (d(eq)) between 3.43 and 6.28 min is investigated at room temperature in a flat, rectangular vessel by means of ultrasound Doppler velocimetry (UDV). GaInSn is used as a working liquid and magnetic flux intensities up to B approximate to 0.918 T are applied. A decelerating effect on the rise velocity is observed at lower, an accelerating effect at medium and a reduction at higher field strengths. Maximum velocities are achieved when the ratio of N/C-D approximate to 1, bubble paths are substantially rectilinear at N/C-D > 2. The mean ascent velocities are compared with literature and data of this work as well as other publications is provided in tables. (C) 2017 Elsevier Ltd. All rights reserved.