Transition to Turbulence and Critical Velocity in Superfluid Solution of 3He in 4He

By the method of oscillating tuning fork, we carried out researches of the transition to turbulence in superfluid solution of 5% 3He in 4He at temperatures of 100 mK–300 mK. The critical velocity υ c of the turbulence appearance is determined through measuring the volt-ampere characteristics. It is established that in the mixture the temperature dependence of the critical velocity is non-monotonous and differs strongly from that in pure 4He. Unlike 4He, the step-like anomalies on resonance curves were observed which, presumably, is connected with instability of the vortex system under the conditions where the core of the vortex is filled by the atoms of 3He. It is shown that such anomalies appear at the temperatures below 0.9 K, at the same time at temperatures below ∼0.5 K they appear even at υ<υ c .