Patent ID: 9190255
Filing Date: 2015-11-17
Classification: H01J

Abstract:
1. A mass spectrometer comprising: ion pulse means for producing ion pulses in a first vacuum chamber, at least one of said pulses comprising a plurality of ions of differing mass-to-charge ratio and differing kinetic energy; ion trap means for receiving and trapping said ion pulses for mass analysis in a second vacuum chamber; ion-optical lens means arranged between the ion pulse means and the ion trap means for receiving said at least one of said pulses which retain said plurality of ions of differing mass-to-charge ratio and differing kinetic energy, and outputting ions therefrom to said ion trap means, comprising a first lens electrode and a second lens electrode collectively defining an optical axis of the ion-optical lens means and adapted for distributing a respective first electrical potential and second electrical potential therealong; lens control means arranged to vary non-periodically with time said first electrical potential relative to said second electrical potential to control as a function of ion mass-to-charge ratio the kinetic energy of ions which have traversed the ion optical lens means thereby to control the mass range of said ions receivable by said ion trap from said ion optical lens means.