Simulation studies of the behavior of positrons in a microtrap with long aspect ratio

The storage capacity of positrons in micro-Penning-Malmberg traps with large length to radius aspect ratios and radii of tens of microns was explored. Simulation studies were conducted with the WARP code and Charged Particle Optics program. A new design of the Penning-Malmberg trap consisting of an array of microtraps with substantially lower end electrode potential than conventional traps was considered. Simulations demonstrated each microtrap with 50 μm radius immersed in a 7T uniform magnetic field could store positrons indefinitely with a density of 1.6 × 1011cm-3 while the confinement voltage was only 10V. For microtraps with radii between 100 μm and 3 μm, the particle density scaled as r-2. Charge clouds developed the expected radial density distribution (that of a soft edge) and rigid rotation evolved to some extent. Plasma confinement time was independent of trap length.