Nanoparticle Dispersion in Superfluid Helium

Rev. Sci. Instrum. 85, 073705 (2014)https://ireap.umd.edu/10.1063/1.48868112014Journal ArticleAdvanced Materials and Nanotechnology

Cryogenic fluid flows including liquid nitrogen and superfluid helium are a rich environment for novel scientific discovery. Flows can be measured optically and dynamically when faithful tracer particles are dispersed in the liquid. We present a reliable technique for dispersing commercially available fluorescent nanoparticles into cryogenic fluids using ultrasound. Five types of fluorescent nanoparticles ranging in size from 5 nm to 1 μm were imaged in liquid nitrogen and superfluid helium, and were tracked at frame rates up to 100 Hz.