Distribution into the quadrupole mass filter with round rods

► Potential field distribution of a quadrupole mass filter with circular cross-section electrodes is described. ► Using superposition principle, we calculate potential around a round rod which is subjected to a given potential. ► By standard separation method, we obtain the potential distribution into the quadrupole mass filter with circular rods. ► Same equivalent operating point in two stability diagrams (having the same βy) the associated modulated secular ion frequencies behavior are the same.