Positive Ion Mobility in Normal and Superfluid 3He at High Magnetic Field

We have measured the mobility of positive ions (“snowballs”) in liquid3He at magnetic fields H = 0 − 12 T and temperatures T = 0.3 − 10 mK. In normal3He, with increasing magnetic field the mobility first increases and then decreases nearly quadratically. The initial rise of the mobility is most strongly seen at the lowest temperatures (T = 2.5−3 mK) and high pressures (p = 29 bar) where at H = 6 T the mobility reaches a maximum enhancement of about 6 %. We attribute this effect to the suppression of the exchange scattering with magnetic field and thus infer the value of the exchange scattering cross-section. In the superfluid A1and A2phases, the relative increase of the ion mobility, as the sample is cooled below the transition temperature, is about twice as small as in the A or B phases.