Suppression of the Superfluid Transition of 3He in 350 nm Channels

We have measured the suppresssion of the superfluid transition temperature due to confinement of the fluid by 350 nm diameter pores in Nuclepore filter. The experiments were carried out at several pressures between 0 bar and 29 bar, where the pressure variation allows us to vary the ratio of the coherence length to pore diameter by approximately a factor of five. The Nuclepore filter was mounted across an annular flow channel which formed part of the inertial bob of a torsional oscillator. Flow was induced by operating the device at its resonant frequency of 850 Hz at amplitudes between 50 pm and 10 nm. The measured suppression of the superfluid transition is less than that predicted by theory.