Cryogenic microjet source for orthotropic beams of ultralarge superfluid helium droplets

Liquid 4He at pressures P(0)=0.5-30 bars and temperatures T(0)=1.5-4.2 K is discharged into vacuum through two different 2 microm nozzles. The velocities of the beam of particles obey the Bernoulli equation down to 15 m/sec. With decreasing T0 and increasing P0 the velocity and angular distributions become exceedingly narrow with Deltav/v less or similar 1% and Deltatheta less or similar 1 mrad. Optical observations indicate that the beam consists of micron-sized droplets (N greater or similar 10(9) atoms). This new droplet source provides opportunities for novel experimental studies of superfluid behavior.