JM..
In
a page of your link, you can find paragraphs,
"Antiparticles have either a positive or a negative electrical charge, so they can be stored in what we call a trap which has the appropriate configuration of electrical and magnetic fields to keep them confined in a small place. Of course, this has to be done in good vacuum to avoid collisions with matter particles. "
However they do not give a clear exposition of what their "trap" is