ION SOURCE FOR PROVIDING A SUPPLY OF CHARGED PARTICLES HAVING A CONTROLLED KINETIC ENERGY DISTRIBUTION

摘要

An ion source device that includes apparatus for pulse injecting ions into a field-free drift region where those ions separate according to their velocities or kinetic energies. A cyclically varying electric field is established at the end of the field-free drift region. Each charged particle enters the electric field at a time determined by its velocity and interacts with the field in a manner dependent upon the phase of the field upon receipt of that particle. The cyclically varying electric field decreases the velocity distribution for particles received during the first half of a cycle, and increases the distribution for particles received during the second half of a cycle. Mass analyzing apparatus is disposed to receive and measure the concentrations of species of charged particles expelled from the cyclically varying field. The output provided by the mass analyzing apparatus also facilitates variation of the cyclically varying electric field to provide a particular species with a desired velocity or kinetic energy distribution.