An experiment is being constructed at Los Alamos to investigate the possibility of using a Penning trap as a fusion confinement device. The goal is to demonstrate electron densities greater than the Brillouin density at the center of the trap by filling it with particles occupying a very restricted region of phase space. The trap under construction has a containment region diameter of 6 mm, standoff lengths of 25 mm, and gaps between electrodes of 1.5 mm. High voltage tests have demonstrated standoff breakdown voltages of ≳100 kV, and established that titanium electrodes offer better performance than stainless steel or copper ones. The main diagnostic of the degree of density focusing will be transmitted beam deflection measurements. The electron source will be biased to inject a probe beam through the trap center, and this will then be imaged on a phosphor screen outside the trap. © 1995American Institute of Physics