Particle Ensembles in Penning Traps

In Particle ensemblescontrast to the situation with a single particle in a trap, the presence of many charged particles gives rise to long-range particle-particle interactions, collective effects, and partial shielding of the trap potential that leads to shifts of the oscillation frequencies. Here, we briefly discuss the most important collective effects and review the treatment of ion ensembles as non-neutral plasmas that show phase transitions between phases including a crystal-like state.