Production and characterization of micron-sized filaments of solid argon

Abstract

A continuous 50-µm-diam filament of solid argon is produced in a moderate vacuum (4.2×10^–3 mbar) by cooling argon gas to 70–90 K over the last 8 mm of a long fused silica capillary. Prior to formation of the straight filament the jet shows different stages characterized by spraying, snowballing, or spiraling filaments as documented by charge-coupled device (CCD) camera microscope pictures. Consecutive CCD pictures are used to measure the filament velocities, which increase with the driving gas pressure P₀ up to about 4.0 cm/s at P₀ = 400 bars with an intermediate peak at about 80 bars. This technique may find applications for producing wall-less cryogenic matrices, targets for laser plasma sources of extreme UV and soft-x-ray sources, plasma implosion experiments, or H₂ pellets for injection into fusion reactors.