Two-dimensional ionization beam profile measurement

Abstract

Equipment for non-destructive, two-dimensional beam profile measurement was developed for the high intensity beam project foreseen at INFN, Legnaro and the K200 variable-energy, separated-sector cyclotron at iThemba LABS. Ions, produced by the interaction of the beam with residual gas, are accelerated in an electrostatic field towards microchannel plates (MCP) for signal amplification. With the first of the two prototypes that were built, ions are accelerated in an electric field between two parallel plates and after passing through an aperture in one of the plates, move through the electric field between two curved plates and consequently bent through ninety degrees before reaching the MCP. The aperture in the plate provides one profile dimension and the spread in the energy of the produced ions the other dimension. In the second prototype two one-dimensional systems, rotated through ninety degrees with respect to each other, were installed in close proximity of each other. The beam profiles measured with both prototypes were compared with those measured with a nearby profile grid. Measurements were made on various beams and with intensities between 10 nA and 1μA.