The physics of non‐neutral plasmas confined on magnetic surfaces is discussed. The Columbia Non‐neutral Torus (CNT), a table‐top ultrahigh vacuum stellarator being constructed at Columbia University, is being built to systematically study non‐neutral plasmas confined on magnetic surfaces. The experimental design is discussed in the context of relevant physics parameters, such as the number of Debye lengths in the device, and the parallel versus perpendicular time scales. © 2003 American Institute of Physics