IceLab, Department of Physics, Umeå University, Umeå, Sweden. luis.rocha@tp.umu.se|IceLab, Department of Physics, Umeå University, Umeå, Sweden. luis.rocha@tp.umu.se|IceLab, Department of Physics, Umeå University, Umeå, Sweden. luis.rocha@tp.umu.se