| 摘要 |
A mass selective ion trap is disclosed having an increased space charge capacity, the trap comprising an expanded three dimensional array of electrodes 301 arranged in two horizontal layers. A RF voltage acts to confine ions in a first (y) direction within a non-quadrupolar pseudopotential well, while a DC voltage (see Figs 4A & 4B) and/or an RF voltage (Fig 4C) acts to confine ions in a second (x) direction within the ion trap. A quadratic DC potential well acts to confine ions in a third (z) direction within the ion trap (Fig 3C). Ions are excited in the third (z) direction and are caused to be mass to charge ratio selectively ejected in the third (z) direction. Also disclosed is an ion trap with a toroidal ion trapping region (Figs 11A-12B), ions being trapped in a first (y) direction by a pseudopotential well and in a radial direction (r) by a quadratic DC potential well. |
