Patent ID: 9425035
Filing Date: 2016-08-23
CPC Classification: H01J

Claim Text:
1. A mass or mass to charge ratio selective ion trap comprising: a first device arranged and adapted either to: (i) generate a radially asymmetric pseudo-potential barrier or well which acts to confine ions in a first (y) and a second (x) direction within said ion trap, or to; (ii) generate a pseudo-potential barrier or well which acts to confine ions in a first (y) direction and a DC potential barrier or well which acts to confine ions in a second (x) direction within said ion trap; a second device arranged and adapted to generate a substantially quadratic DC potential well which acts to confine ions in a third (z) direction within said ion trap; and a third device arranged and adapted to excite ions in said third (z) direction so as to mass or mass to charge ratio selectively eject ions in said second (x) direction or in said third (z) direction from an ion ejection region of said ion trap; wherein a profile of said substantially quadratic DC potential well progressively varies along two directions, said second (x) direction and said third (z) direction, so that an electric field is maintained along said second (x) direction, wherein a magnitude of the electric field in said second (x) direction varies with position in said third (z) direction so that said electric field urges, channels or directs ions towards said ion ejection region wherein said electric field causes ions to experience substantially different acceleration fields in said second (x) direction dependent upon a relative position of said ions in said third (z) direction.