Artificially structured boundary for confinement of effectively unmagnetized cryogenic antimatter plasmas

An artificially structured boundary (ASB) produces a short-range, static electromagnetic field that can reflect charged particles. In the work presented, an ASB is considered to consist of a spatially periodic arrangement of electrostatically plugged magnetic cusps. When used to create an enclosed volume, an ASB may confine a non-neutral plasma that is effectively free of applied electromagnetic fields, provided that the spatial period of the ASB-applied field is much smaller than any one dimension of the plasma. As envisioned, a non-neutral positron plasma could be confined by an ASB along its edge, and the space charge of the positron plasma would serve to confine an antiproton plasma. If the conditions of the two-species plasma are suitable, production of antihydrogen via three-body recombination for antimatter gravity studies may be possible. Particle-in-cell (PIC) simulations are used to study radial confinement of non-neutral and partially neutralized plasmas in a cylindrically symmetric ASB trap. For the timescales and plasma conditions considered in this work, plasma losses are found to be negligible.