Theoretical Evaluation of Ion Funnel Focussing for Light Ions in a Drift Tube
EMSL Project ID
2501
Abstract
The object of the project is to perform some ion trajectory simulations to evaluate the potential benefit of using an ion funnel to focus light ions in the Proton Transfer Reaction Mass Spectrometer (PTR-MS) instrument and other CIMS instruments using drift tubes or flow tubes for trace gas analysis in air. The PTR-MS is a commercial instrument used to measure organic trace gases in air down to the low pptv range. It uses H3O+ as a reagent ion to ionize analyte gases by proton transfer reaction within a drift tube. The drift tube has an internal diameter of approximately 5 cm and the acceptance orifice into the mass spectrometer is a 1 mm diameter hole. It is anticipated that placing an ion funnel at the end of the drift tube would increase ion transmission into the mass analyzer. What needs to be determined are the ion funnel parameters (electrode dimensions, spacing, voltages, RF frequency) for effective focusing of low mass ions in the range 19 - 250 amu and the estimated gain in ion current for the PTR-MS. The benefits of using a lightion funnel will then be weighed against the alternative approach of applying RF focusing directly to the drift tube rings on the PTR-MS.
Project Details
Project type
Capability Research
Start Date
2002-05-13
End Date
2002-09-25
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members