Capping the tube works, but complicates build anything approaching a practical sorter. Also with using helium it still leaks a little, but through the walls.
Next I figured using a tube 32 Angstroms long would make for a pretty short tube. I tripled the length . The contents stay in. It is my hope they stay in long enough for things to get up to speed.
Other things I tried before these two:
- deleting half the atoms
- plugging it with a fullerene- it made a cannon
- decreasing the rotation
Longish sim on the longish tube overnight.