Mapping ion stability in digitally driven ion traps and guides

Abstract

Spreadsheet based programs for facile production of stability diagrams have been developed to accommodate the need for rapid generation for any change in the duty cycle of rectangular waveforms. In this publication, we have used these programs to demonstrate the effects of duty cycle manipulation and visually revealed the changes in the stability diagrams for each change. The concept of equating duty cycle change with a change in the Mathieu parameter a has been reexamined and found to be incorrect with respect to matrix methods definitions. The suggestion that the 50% duty cycle stability region can be mapped by varying the duty cycle to scan along lines of constant a/q is also shown to be incorrect. These observations were possible because the spreadsheet program allowed quick alteration of the waveforms and then observation of the stability results. Finally, the needs of the operator were examined. Because the stability diagrams have to be recalculated with each change in duty cycle, it is more helpful to use the matrix methods to directly calculate the stability diagrams at a=0 as a function of m/z and frequency. It is our intention to make these spreadsheet programs freely available to facilitate the mainstreaming of digital ion trap and guide technology.