Electron confinement in an annular Penning trap

Electron confinement in an annular version of a Malmberg-Penning trap [S. Robertson and B. Walch, Rev. Sci. Instrum. 70, 2993 (1999)] has been investigated for conditions in which mobility is the dominant source of transport. A non-neutral plasma of electrons is contained in the annular region between coaxial cylinders. An axial magnetic field provides radial confinement and electric bias potentials provide axial confinement. The electric field that drives transport is determined primarily by the potential difference applied to the cylinders. The measured density decay rates have the expected dependence upon electric field, collision frequency and magnetic field and are within a factor of 2 of calculated values. Experiments are performed with an axial field of 5-18 mT, a radial electric field of 11-38 V/cm, a helium pressure of 0.01-0.13 mTorr, an initial electron density of similar to 10(6) cm(-3), and the density decay times are 1-10 ms. (C) 2000 American Institute of Physics. [S1070-664X(00)03406-6].