Note that they use carbon nanotubes as the basis for those silicon 0.2 micron [not really nano-] tubes. Carbon is about 20x smaller than silicon — Far more likely to have individualized linear sets of atoms traveling in the smaller tube.
And once a fusion reaction happens, nothing is strong enough to hold it in place.
The silicon could act as a reinforcement to the carbon tubes, like a tube within a tube.
But maybe with this new material, called hexagonal boron nitride, it could even be stronger still................