Positron Plasma in the Laboratory

We have developed a method to accumulate and store positrons, from a $^{22}\mathrm{Na}$ radioactive source, in an electrostatic trap using a tungsten moderator and inelastic collisions with nitrogen molecules. The resulting positron gas is found to cool to room temperature, and to fulfill the criteria for a single-component, positron plasma. The cooling and confinement processes and the potential applications of this many-positron system are discussed.