Spatial separation of fringe fields in quadrupole mass filters

Abstract

The use of leaky dielectric materials which appear to radio‐frequency fields as dielectrics but to dc fields as conductors is described in connection with achieving a delayed‐dc‐ramp effect in quadrupole mass filters. The criteria for the conductivity and dielectric constant of the materials are derived theoretically. Some theoretical considerations with regard to application to practical mass filters are also presented. Apparent experimental verification of the theory is briefly described and practical problems of available materials are discussed.