Investigation by simulation of the RF carpets for the transport of ions at atmospheric pressures

Abstract

Ion funnels, quadrupole, and multipole are well-known ion optic methods for transportation of ions. However, the methods are suitable for pressures below 30–40 Torr. The main loss of ions occurs in an inlet of mass spectrometer at atmospheric pressure. This work offers a focusing system, which employs a fine-structure electrode ion carpet. The focusing efficiency of fine-structure electrode was investigated by computer simulation methods and it was compared with theoretical estimation. The methods demonstrated good agreement with each other that promises a reliability of results. The authors found an optimal fine-structure electrode ion carpet configuration (electrodes width of 10 µm), which demonstrates suitable focusing efficiency and can be implemented in practice.

The Dynamics of Ions on Phased Radio-frequency Carpets in High Pressure Gases and Application for Barium Tagging in Xenon Gas Time Projection Chambers

“…Since inter-collision curvature is the hallmark of RF carpet operation that allows for ion levitation, validity of the SDS model for our purposes appears questionable. Similar conclusions have been reached by other authors, regarding use of the SDS model at radio frequencies and high pressures [31,36,37]. A second approach involves micro-physically simulating the trajectory collision-by-collision with hardsphere interactions [38].…”

“…Here we explore an alternate approach, the application of ultra-fine pitch RF carpets to the problem of ion transport in dense xenon gas for barium tagging. The required carpets are of similar form to those proposed for ion catching in atmospheric pressure air in Ref [31]. In this scenario, RF transport is implemented without gas flow to sweep barium ions arriving at a detector cathode to a few small single molecule fluorescence sensors [26].…”

“…Manufacturing methods for RF structures used in ion traps for quantum information processing have, however, achieved far finer feature sizes than 50 µm [32,57,58,33,59] and manufacture by photo-etch on sapphire or by CMOS production both appear possible for achieving feature sizes as small as 5µm [34]. RF carpets of this scale have been proposed, but not yet demonstrated, by others [31]. Ongoing R&D within the NEXT collaboration aims to produce an RF carpet by single-layer photo-etch on sapphire of pitch of 15µm for experimental studies of ion transport in xenon gas.…”