RESUMO
We consider the operation of a digital linear ion trap with resonant radial ejection. A sequence of rectangular voltage pulses with a dipole resonance signal is applied to the trap electrodes. The periodic waveform is piecewise constant, has zero mean, and is determined by an asymmetry parameter d $$ d $$ : one value is taken on interval 0 dT $$ \left(0, dT\right) $$ and another on dT T $$ \left( dT,T\right) $$ , where T $$ T $$ is the RF period. Ion mass scanning is performed by varying the asymmetry parameter d $$ d $$ and amplitude of the negative pulse part with time. The ion oscillation frequencies and acceptance of the linear trap are calculated. The dependence of the ion mass to charge ratio m / z $$ m/z $$ on the parameter d $$ d $$ is m / z ~ d 2 $$ m/z\sim {d}^2 $$ . The maximum value is about m / z = 30 $$ m/z=30 $$ kDa for typical parameters of the linear trap: frequency 0.5 MHz, rod radius 4 mm, and negative pulse amplitude 1 kV. The dipolar excitation frequency is 0.125 MHz at which the LIT acceptance is maximal.