Patent ID: 11011364

Abstract:
An apparatus configured to produce an image charge/current signal representative of trapped ions undergoing oscillatory motion. The apparatus includes: an electrostatic ion trap configured to trap ions such that the trapped ions undergo oscillatory motion in the electrostatic ion trap; an image charge/current detector configured to obtain an image charge/current signal representative of trapped ions undergoing oscillatory motion in the electrostatic ion trap, wherein the electrostatic ion trap configured to trap ions such that the image charge/current signal in the time domain repeats, for ions of a given mass/charge ratio m, at a frequency fsig(m) [Hz] with a signal period Tsig(m) [s]. The image charge/current detector includes one or more pickup electrodes configured to obtain the image charge/current signal. The one or more pickup electrodes are arranged to detect two signal pulses caused by ions having the given mass/charge ratio m within each signal period Tsig(m). The one or more pickup electrodes are further arranged such that the time separation Δtsep(m) between the two signal pulses caused by ions having the given mass/charge ratio m within each signal period Tsig(m) is approximately equal to 2p+1/2.n.fsig(m) so as to suppress a predetermined nth harmonic within the image charge/current signal, where n is an integer that is 1 or more, and where p is an integer that is 0 or more.