LAUSR

Abstract We consider an input ion beam that has Gaussian distributions of the initial ion coordinates and transverse velocities at the entrance of a quadrupole mass filter (QMF) with round rods. To calculate the statistical QMF acceptance, an ion trajectory method has been used. The probability density functions of accepted points on phase planes of transverse ion positions and velocities in the X and Y directions are used to visualize the distributions of phase space points. To determine the statistical acceptances we calculate the second moments of the probability density functions. We define the statistical acceptance of the quadrupole mass filter as the area of an ellipse on the phase plane determined by the second moments. The values of the second moments characterize the efficiency of the coupling of the Gaussian ion source and the acceptance of a quadrupole rod set with round rods. The above approach is a supplement to a previously published theoretical model of QMF fields with circular electrodes.