Research Of The Hybrid Ion Trap Mass Analyzer

With the development of science and technology, the mass spectrometer (MS) plays an increasingly important role in the field of chemical analysis and detection, and it has become an indispensable analytical tool in many related industries. As a core component of a mass spectrometer, the mass analyzer determines important criteria such as: the mass resolution, sensitivity and mass range. Common mass analyzers include ion trap, magnetic sector, quadrupole, and time-of-flight. Compared with the other mass analyzers, the ion trap analyzer possesses distinct advantages such as compact size, structural simplicity, and the abilities to perform tandem mass spectometry and operate at a relatively higher pressure. Therefore it is widely used in commercial mass spectrometers.Improving upon the linear ion trap (LIT) and rectilinear ion trap (RIT), this research defines a plane-hyperbolical hybrid ion trap (HIT) mass analyzer which combines characteristics of both LIT and RIT. Like other linear ion traps, the HIT also has four electrodes and forms a quadrupolar field. The HIT has endcap electrodes with DC voltages that form a potential well in the z-direction. The y-electrode of HIT is planar as the RIT. There is an improved slit in the center of hyperboloid-shaped x-electrode to eject ion out of the trap. This design retains RIT’s advantages of easy fabrication and simple assembly, but corrects the electric-field defects of the RIT’s x-electrodes, thus improves the performance of the mass analyzer.SIMION software was used to simulate the internal electric-field of HIT.. The simulated parameters include dual-curved surface curvature; x-axis direction stretching distance; and length and width of the slit. The main aim is to find the optimum design of HIT for its quadrupolar field coefficient and higher-order field coefficients. Also,both the RF frequency and gas pressure were optimized for the operation of the HIT.A prototype of HIT was designed, fabricated, tested, and compared with the HIT and LIT. The mechanical design of the HIT was created by Solidworks. After fabrication and assembly, the HIT was installed on a research mass spectrometer. It was tested by using PFTBA, and mass spectra were obtained. The results show that under the same conditions, the mass resolution and sensitivity of the HIT are better than those of the RIT. In addition, the performance of the HIT is almost the same as linear ion trap mass analyzer.